F.J. Tipler: what's his reputation?
David M. Pfarrer
not a scientist and I don't have much math, so before I invest anymore
time in what looks like a facinating book I'd like to hear some
informed opinions about the author.
What's his reputation in the field? Are his ideas taken seriously by
his colleagues? Do they think he's a crackpot? If so, do they think
he's a brilliant crackpot?
Many thanks.
****************************************************
| David Pfarrer | "Respect means, put |
| pfa...@isr.harvard.edu | yourself out" |
| pfa...@harvunxw.bitnet | - Pascal |
****************************************************
Sean Carroll
>I've been looking at F.J. Tiplers "The Physics of Immortality." I'm
>not a scientist and I don't have much math, so before I invest anymore
>time in what looks like a facinating book I'd like to hear some
>informed opinions about the author.
>
>What's his reputation in the field? Are his ideas taken seriously by
>his colleagues? Do they think he's a crackpot? If so, do they think
>he's a brilliant crackpot?
>
Tipler has done perfectly respectable (although not groundbreaking)
work in general relativity. So I would listen carefully to anything
he says in that narrow technical area. But achieving competence in one
area does not prevent one from saying crazy things in another area,
and Tipler does have a bit of a reputation for making (what most people
consider to be) outlandish claims.
So you should try to judge his book on its own merits, not from any
authority he has from having done good work in general relativity.
Honestly, from the little I have heard, it is unlikely that the work
on immortality would be taken at all seriously by most physicists.
--Sean
Barry Merriman
Sarfatti) writes:
>
> Yes, that is true, but that is not to the credit of most physicists who are
> in general a rather timid, fearful, afraid of losing their jobs, lot.
> Actually that's true of most faculty in academia which is why I quit back in
71.
I sort of agree (but they don;t fear losing their tenured jobs:-).
I would be interested to hear what your academic life was like,
given that you've gone on to a less conventional life now.
--
Barry Merriman
UCLA Dept. of Math
UCLA Inst. for Fusion and Plasma Research
ba...@math.ucla.edu (Internet; NeXTMail is welcome)
Jack Sarfatti
>
>In <330hum$k...@senator-bedfellow.MIT.EDU> car...@marie.mit.edu (Sean Carroll) writes:
>
>>
>>In article <33038i$5...@scunix2.harvard.edu> pfa...@isr.harvard.edu (David M. Pfarrer) writes:
>>>I've been looking at F.J. Tiplers "The Physics of Immortality."
>
>Is the book in the stores already?
>>>
Yes.
Jack Sarfatti
>
>In article <332l62$3...@ixnews1.ix.netcom.com> sarf...@ix.netcom.com (Jack
>Sarfatti) writes:
>>
>> Yes, that is true, but that is not to the credit of most physicists who are
>> in general a rather timid, fearful, afraid of losing their jobs, lot.
>> Actually that's true of most faculty in academia which is why I quit back in
>71.
>
>I sort of agree (but they don;t fear losing their tenured jobs:-).
>
>I would be interested to hear what your academic life was like,
>given that you've gone on to a less conventional life now.
>
>--
>Barry Merriman
>UCLA Dept. of Math
>UCLA Inst. for Fusion and Plasma Research
>ba...@math.ucla.edu (Internet; NeXTMail is welcome)
>
>
>
You must remember that was in the late 60's and early 70's. I found teaching
at San Diego State to be boring. I was burned out after four years and most
of the faculty were boring etc. I threw away a lot of financial security
but I had great adventures and lots of beautiful women all over the world -
you can read my memoirs by downloading "Sarfatti's Illuminati" on WELL GOPHER.
The films Ghost Buster's, Back From The Future, Close Encounters of The Third
Kind, Peggy Sue Got Married and Time Bandits might not have even been conceived
were it not for my activities at Esalen in Big Sur in mid 70's and my
connections to Francis Ford Coppola's circle at that time. Dancing Wu Li
Masters would not have been written and Tao of Physics might not have gotten
published. I have certainly "made a difference" in pop culture - and now with
internet, CD and new TV I am just getting started. You ain't seen nothin yet! :-)
James Kibo Parry
> He is not a crackpot.
In sci.physics article <335cra$b...@ixnews1.ix.netcom.com>,
Jack Sarfatti <sarf...@ix.netcom.com> wrote:
> You must remember that was in the late 60's and early 70's. I found teaching
> at San Diego State to be boring. I was burned out after four years and most
> of the faculty were boring etc. I threw away a lot of financial security
> but I had great adventures and lots of beautiful women all over the world -
> you can read my memoirs by downloading "Sarfatti's Illuminati" on WELL GOPHER.
> The films Ghost Buster's, Back From The Future, Close Encounters of The Third
> Kind, Peggy Sue Got Married and Time Bandits might not have even been conceived
> were it not for my activities at Esalen in Big Sur in mid 70's and my
> connections to Francis Ford Coppola's circle at that time. [...]
So let me get this straight... Tipler is not a crackpot because you said
so and we know we can trust you because you claim to have perhaps personally
imspired just about every science fiction film made in the last twenty
years (including the final episode of "Star Trek: TNG", you mentioned
once) because you knew someone who knew Francis Ford Coppola
who knew Roger Corman who at the time was making films that Steven
Spielberg, Ivan Reitman, Terry Gilliam, Bob Zemeckis, etc. might have seen
a few decades before they made "Ghostbusters", "Back From The Future",
"Time Bandits", etc.? Or am I missing a step in your reasoning?
Can you please draw me a diagram of how you knowing some of the same people
as Francis Ford Coppola does, proves that Tipler is not a crackpot?
I know little about Tipler, but I don't see how your knowing people in
Hollywood ties in with the grand scheme here.
In fact, I don't see what your activities in the world of physics could
have to do with, say, "Ghostbusters", a wacky comedy about people who
shoot lightning bolts at a giant marshmallow man, unless you've been
researching ways ghosts can cover people with green slime. Now, if
you'd said you inspired the monsters Coppola built for Corman's "Battle
Beyond the Sun", that would have been much more plausible. Or Jack
Hermann's speech in "The Yesterday Machine". But "Ghostbusters"?
-- K.
all IMHO, of course.
P.S. The part about "having lots of beautiful women" is relevant, though.
Please tell us more.
Jack Sarfatti
>
>In sci.physics, Jack Sarfatti wrote:
>> He is not a crackpot.
>
>In sci.physics article <335cra$b...@ixnews1.ix.netcom.com>,
>Jack Sarfatti <sarf...@ix.netcom.com> wrote:
>> You must remember that was in the late 60's and early 70's. I found teaching
>> at San Diego State to be boring. I was burned out after four years and most
>> of the faculty were boring etc. I threw away a lot of financial security
>> but I had great adventures and lots of beautiful women all over the world -
>> you can read my memoirs by downloading "Sarfatti's Illuminati" on WELL GOPHER.
>> The films Ghost Buster's, Back From The Future, Close Encounters of The Third
>> Kind, Peggy Sue Got Married and Time Bandits might not have even been conceived
>> were it not for my activities at Esalen in Big Sur in mid 70's and my
>> connections to Francis Ford Coppola's circle at that time. [...]
>
>So let me get this straight... Tipler is not a crackpot because you said
>so
Yes, and because he has published papers in peer-reviewed journals, has book
with Barrow published by Oxford, got a half million dollar advance from Double
Day and is a Professor of Physics at Tulane in New Orleans. Hardly the profile
of a crackpot!
>and we know we can trust you because you claim to have perhaps personally
>imspired just about every science fiction film made in the last twenty
>years (including the final episode of "Star Trek: TNG", you mentioned
>once) because you knew someone who knew Francis Ford Coppola
No, do your homework, my book Space Time and Beyond (Dutton 1975) was
widely read in Hollywood. I met a lot of Hollywood people and was part of
Francis Coppola's inner social circle for awhile spending lots of time
at his house (then at 2800 Broadway, going to cafes, restaurants with him -
genrally hanging out and talking about time travel and paranormal etc meeting
Milos FOrman, Jack Nicholson, Mike Dougles, Spielberg, Lucas, Saul Zaentz, and
many others. I brought Uri Geller to Francis's house where he did his tricks for
a lot of people. I brought Jacques Vallee there, as a result Jacques became technical
director for Close Encounters of the Third Kind and the character played by
Francois Truffault is based on Vallee. The opening scene of Back to the Future
is based on a famous incident in North Beach involving Kim Burrafto my sidekick
who blasted Savoy Tivoli with huge speakers from a block away when Spielberg
and his crew were hanging out there - Kim was notorious for riding his bike
in short pants which inspired the skateboard scene with the large speaker at
beginning of film. Ellie Coppola did Peggy Sue and she was one of my fans and
we spent a lot of time together. As for Ghost Busters, Dan Akroyd's close
friend the late George Koopmann was one of our investors and Dan mentions
the impact of the New Physics specifically quantum mechanics on the idea of
the script in a book on the making of Ghost Busters.
>who knew Roger Corman who at the time was making films that Steven
>Spielberg, Ivan Reitman, Terry Gilliam, Bob Zemeckis, etc. might have seen
>a few decades before they made "Ghostbusters", "Back From The Future",
>"Time Bandits", etc.?
Time Bandits script was written by a close friend of Bob Toben the artist who
did the cartoons in Space Time and Beyond. The film is a direct effect of that silly
book which had surprising big impact in the movie world.
>Or am I missing a step in your reasoning?
>Can you please draw me a diagram of how you knowing some of the same people
>as Francis Ford Coppola does, proves that Tipler is not a crackpot?
This is your confusion Kibo - you got some screws missing in your brain. I
never said or even remotely implied there was such a connection. In your
schizoid lapse of attention you garbled two distinct paragraphs - in one I
gave my opinion of Tipler, in another I responded to Barry Merriman's direct
question to me.
>I know little about Tipler, but I don't see how your knowing people in
>Hollywood ties in with the grand scheme here.
>
>In fact, I don't see what your activities in the world of physics could
>have to do with, say, "Ghostbusters", a wacky comedy about people who
>shoot lightning bolts at a giant marshmallow man, unless you've been
>researching ways ghosts can cover people with green slime. Now, if
>you'd said you inspired the monsters Coppola built for Corman's "Battle
>Beyond the Sun", that would have been much more plausible. Or Jack
>Hermann's speech in "The Yesterday Machine". But "Ghostbusters"?
Yes, Kibo Ghostbusters, especially Ghostbusters, I am a Ghostbuster remember, we
were the physicists researching Ghosts (ESP) at Esalen. As I sai, the connection to
Ghost Busters is very direct via George Koopman who influenced writing of the script
and who was promoting me and my Esalen group - the scene in Ghost Busters where the
State College professor seduces the young coed is based directly on Fred Alan Wolf's
and my activities as Physics Professors at San Diego State where we made love to lots
of very pretty coeds, - though not ones in our classes -often two or more in one day
- ah youth! I was in my late 20's when I was a prof there and was not much older
than the coeds.
>P.S. The part about "having lots of beautiful women" is relevant, though.
> Please tell us more.
San Diego State is loaded with gorgeous friendly girls -- or was in the 60's! -
blondes, redheads, brunettes, with fabulous Play Boy Bunny figures, generally took me
about an hour from first meeting into bed. This was pre-herpes, pre-AIDS, I never
even got VD - those were they days, my friend, we thought they'd never end! But
they did! The only thing I regret about quitting my job at San Diego State -
is the girls! Fred shot a film with a bunch of naked really spectacular coeds and me
on the nude beach in La Jolla, Black's Beach where I play GOD* coming out of the sea.
We had this old Argentine Movie Director with green shoes who was practically blind
directing. It actually was a good film.
* I was type-cast at a young age.
PS Koopman staged the military scenes at end of Blues Brothers - he was an
intimate part of the Belushi-Akroyd scene. Remember, I was part of the Leary scene
and Koopman was Leary's manager after Tim got out of jail. First thing Tim did
was come up and hang out with us at Esalen. Koopman arranged a big conference
with Tim, me, Nick Herbert, Fred Wolf, Saul Paul Sirag, Robert Anton Wilson ...
at Arthur Young's Institute on Ashby in Berserkely that was videoed.
Michael Clive Price
Date: Sun, 21 Aug 94 17:25:24 GMT
Organization: MCP plc
Reply-To: pr...@price.demon.co.uk
X-Newsreader: Simple NEWS 2.0 (ka9q DIS 1.24)
Lines: 36
David Pfarrer mentions Frank J Tipler's "The Physics of Immortality."
I shan't comment on the Omega Point theory of Tipler, but I was
delighted to read on page 170-1 of the (unpublished) results of a poll
conducted by "political scientist" L David Raub on 72 of the "leading
cosmologists and other quantum field theorists" about the "Many-Worlds
Interpretation" [sic]. The result:
1) Yes, I think MWI is true 58%
2) No, I don't accept MWI 18%
3) Maybe it's true but I'm not yet convinced 13%
4) I have no opinion one way or the other 11%
No shockers there. We've known for a long time that majority of quantum
cosmologists or QG folks subscribe to many-worlds. But there's more.
Amongst the "Yes, I think MWI is true" crowd are (or were) Gell-Mann,
Hawking and.... Feynman! (Weinberg is also mentioned as a many-worlder,
although it's not clear on whether he was polled.) The poll was conducted,
presumably, before 1988 (when Feynman died). The only "No, I don't
accept MWI" mentioned by name is Penrose.
Feynman an Everett fan!!! My jaw hit the floor.
It was worth reading just for that. Ho, ho, ho. :-)
Have a nice day folks (I know I shall!).
Mike Price pr...@price.demon.co.uk
Frank Reed
the Many Worlds Interpretation? Is it just that it's hard to imagine
Feynman adopting *any* metaphysical position? It's always seemed to
me that 'Many Worlds' was the best way to describe Feynman's sum over
histories math.
-Frank E. Reed
Jack Sarfatti
Yes, that is a reasonable inference. However, Heisenberg's "potentia"
also works. The particle is potentially on all the paths. Actually
Feynman's model fits Bohr's Copenhagen interpretation quite nicely.
Feynman was definitely a pragmatist - a really smart engineer value system
with a lot of carisma and genius.
Jack Sarfatti
>The only "No, I don't
>accept MWI" mentioned by name is Penrose.
>
> Feynman an Everett fan!!! My jaw hit the floor.
>
>It was worth reading just for that. Ho, ho, ho. :-)
>Have a nice day folks (I know I shall!).
>
>Mike Price pr...@price.demon.co.uk
>
Not so fast, Mike. Bohm's paradigm is totally consistent with an effective
many-worlds quantum cosmology in which the actual particles and fields of
the universe are in one of the branches.
James Kibo Parry
Jack Sarfatti <sarf...@ix.netcom.com> wrote:
> Yes, Kibo Ghostbusters, especially Ghostbusters, I am a Ghostbuster remember, we
> were the physicists researching Ghosts (ESP) at Esalen. As I sai, the connection to
> Ghost Busters is very direct via George Koopman who influenced writing of the script
> and who was promoting me and my Esalen group - the scene in Ghost Busters where the
> State College professor seduces the young coed is based directly on Fred Alan Wolf's
> and my activities as Physics Professors at San Diego State where we made love to lots
> of very pretty coeds, - though not ones in our classes -often two or more in one day
> - ah youth! I was in my late 20's when I was a prof there and was not much older
> than the coeds.
I am speechless. Especially since I didn't know that Columbia
University's real name was "State College". They changed it to protect
the innocent, right?
Weren't you also the model for one of the new characters in _Ghostbusters II_?
I'm thinking of the sequence with Bill Murray discussing physics with a
lot of people with new ideas.
> they did! The only thing I regret about quitting my job at San Diego State -
> is the girls! Fred shot a film with a bunch of naked really spectacular coeds and me
> on the nude beach in La Jolla, Black's Beach where I play GOD* coming out of the sea.
> We had this old Argentine Movie Director with green shoes who was practically blind
> directing. It actually was a good film.
Please tell us where to get it. I *must* see this!
-- K.
It's presumably not as chock-full of
quantum physics as _Ghostbusters_.
Weasel Boy
: Yes, and because he has published papers in peer-reviewed journals, has book
: with Barrow published by Oxford, got a half million dollar advance from Double
: Day and is a Professor of Physics at Tulane in New Orleans. Hardly the profile
: of a crackpot!
Well, that chick that implores people to STOP THE MADNESS got about a
$1.5 million advance on a book by Doubleday. Is she also not a crackpot?
And what about Carl Sagan? He's a Professor too. Is he not a crackpot? I
have articles in peer-reviewed journals -- All it means is that only my
friends read them.
: widely read in Hollywood. I met a lot of Hollywood people and was part of
: Francis Coppola's inner social circle for awhile spending lots of time
: at his house (then at 2800 Broadway, going to cafes, restaurants with him -
: genrally hanging out and talking about time travel and paranormal etc meeting
: Milos FOrman, Jack Nicholson, Mike Dougles, Spielberg, Lucas, Saul Zaentz, and
: many others. I brought Uri Geller to Francis's house where he did his tricks for
: a lot of people. I brought Jacques Vallee there, as a result Jacques became technical
: director for Close Encounters of the Third Kind and the character played by
: Francois Truffault is based on Vallee. The opening scene of Back to the Future
: is based on a famous incident in North Beach involving Kim Burrafto my sidekick
: who blasted Savoy Tivoli with huge speakers from a block away when Spielberg
: and his crew were hanging out there - Kim was notorious for riding his bike
: in short pants which inspired the skateboard scene with the large speaker at
: beginning of film. Ellie Coppola did Peggy Sue and she was one of my fans and
: we spent a lot of time together. As for Ghost Busters, Dan Akroyd's close
: friend the late George Koopmann was one of our investors and Dan mentions
: the impact of the New Physics specifically quantum mechanics on the idea of
: the script in a book on the making of Ghost Busters.
You're trolling, right? Everyone knows that Uri Geller was a fake.
All this proves to me is that you're a shameless name dropper who doesn't
have enough confidence in himself so he relies on the names on people he
claims to have met. Besides, if all these people used your ideas, why
aren't you given credit, royalties, and more fame than you have right
now?
: PS Koopman staged the military scenes at end of Blues Brothers - he was an
: intimate part of the Belushi-Akroyd scene. Remember, I was part of the Leary scene
: and Koopman was Leary's manager after Tim got out of jail. First thing Tim did
: was come up and hang out with us at Esalen. Koopman arranged a big conference
: with Tim, me, Nick Herbert, Fred Wolf, Saul Paul Sirag, Robert Anton Wilson ...
: at Arthur Young's Institute on Ashby in Berserkely that was videoed.
Do you know Skip Williamson? I got drunk with him at a party on Saturday.
He just turned 50.
I'm a shameless name-dropper too, sometimes. And don't be so hard on us
Kibologists. We're allowed.
--
====================================================================
Darren P. Mckeeman | 'The eagle may soar, but a weasel never gets
Freelance Writer | sucked into a jet engine' - Simon & Simon
IT'S TIME! Ask me for details! Don't get caught short on 09/17!
====================================================================
Jack Sarfatti
>
>Weren't you also the model for one of the new characters in _Ghostbusters II_?
>I'm thinking of the sequence with Bill Murray discussing physics with a
>lot of people with new ideas.
I didn't even see II. I'll have to look. Yeah the Bill Murray character is
partly based on a composite of Fred Alan Wolf and me. Fred won American Book
Award in 1982 for Taking The Quantum Leap and has seven books in print from
major publishers. We are reissuing them on CD ROM.
>
>> they did! The only thing I regret about quitting my job at San Diego State -
>> is the girls! Fred shot a film with a bunch of naked really spectacular coeds and me
>> on the nude beach in La Jolla, Black's Beach where I play GOD* coming out of the sea.
>> We had this old Argentine Movie Director with green shoes who was practically blind
>> directing. It actually was a good film.
>
>Please tell us where to get it. I *must* see this!
>
> -- K.
> It's presumably not as chock-full of
> quantum physics as _Ghostbusters_.
The film appears to be lost with Fred's moves. Hopefully we will find it in
Santa Fe New Mexico with Fred's ex-wife Judith who owns a very chic artsy
local magazine there. It was made 24 years ago. I hope to find it and put it as
part of a CD.
>
>
Jack Sarfatti
>
>Well, that chick that implores people to STOP THE MADNESS got about a
>$1.5 million advance on a book by Doubleday.
Oh yeah? I want to marry her!
>Is she also not a crackpot?
As long as she puts a chicken in my pot! Besides, crackpots are better
in bed!
>And what about Carl Sagan? He's a Professor too. Is he not a crackpot?
Carl is much too boring to be a crackpot. No, he is not a crackpot.
>I
>have articles in peer-reviewed journals -- All it means is that only my
>friends read them.
And tenure committees.
>You're trolling, right? Everyone knows that Uri Geller was a fake.
I agree, Uri is a fake, but that does not change the fact, that I brought him
to Francis Coppola's house. I also brought Uri to a wild sex orgy on a houseboat
in Sausalito in his chauffer-driven Rolls Royce - and he was quite shocked.
>
>All this proves to me is that you're a shameless name dropper who doesn't
>have enough confidence in himself so he relies on the names on people he
>claims to have met.
Say that to my face, buster!
I guess every historian or person who writes his memoir is a "name dropper"
or there would be nothing of interest to write about on that level. Newspaper
reporters are name droppers. So I am a name dropper so what.
>: PS Koopman staged the military scenes at end of Blues Brothers - he was an
>: intimate part of the Belushi-Akroyd scene. Remember, I was part of the Leary scene
>: and Koopman was Leary's manager after Tim got out of jail. First thing Tim did
>: was come up and hang out with us at Esalen. Koopman arranged a big conference
>: with Tim, me, Nick Herbert, Fred Wolf, Saul Paul Sirag, Robert Anton Wilson ...
>: at Arthur Young's Institute on Ashby in Berserkely that was videoed.
>
>Do you know Skip Williamson? I got drunk with him at a party on Saturday.
>He just turned 50.
I nevah hoid of da bum!
>I'm a shameless name-dropper too, sometimes. And don't be so hard on us
>Kibologists. We're allowed.
The Curse of SAR is upon you! Sweet Dreams! :-<
When you want the Curse lifted let me know. It will cost you! I accept,
Bank Americard, Vica, Discovery, and American Express.
Bruce Scott TK
Did you _really_ lay off the women in your classes?
--
Gruss,
Dr Bruce Scott The deadliest bullshit is
Max-Planck-Institut fuer Plasmaphysik odorless and transparent
b...@ipp-garching.mpg.de -- W Gibson
David Pearce
-- If Everett is right then there must be a vast multitude
(albeit very small percentage) of worlds of unimaginable
frightfulness (far worse than Auschwitz) which are no
less real than this particular branch of the Universal
wavefunction. I agree the case for the MWI is compelling,
but unlike some of its enthusiastic supporters, I profoundly
hope we are wrong: its implications are dreadful.
Dave Pearce
dav...@mdjf.demon.co.uk
Weasel Boy
: I guess every historian or person who writes his memoir is a "name dropper"
: or there would be nothing of interest to write about on that level. Newspaper
: reporters are name droppers. So I am a name dropper so what.
I happen to agree with you about this one. You have passed my 'let's read
the whole post before I followup' test.
: >Do you know Skip Williamson? I got drunk with him at a party on Saturday.
: >He just turned 50.
: I nevah hoid of da bum!
Well, from what I could tell, he was a cartoonist working at Playboy with
ol' Pope R.A.W. and they are pretty good friends. Oh well, I once had to
take care of Mr. Wilson's $142.60 bar tab, so I've got that to name drop
about.
: The Curse of SAR is upon you! Sweet Dreams! :-<
Does this mean I'll get to pen the storyline for an upcoming movie called
Ghostbusters of the Third Kind? Will I have any input on David Lynch's
next project? Or will I just move to Seattle and steal all the marijuana
people leave on Jimi Hendrix's grave? If so, then I accept.
: When you want the Curse lifted let me know. It will cost you! I accept,
: Bank Americard, Vica, Discovery, and American Express.
I've always wanted a VICA card. I hear it's one of those that doesn't
actually use money, but the barter system. You buy something with the
VICA card, and then you send them something worth approximately what you
bought. Say you buy a new stereo -- you'd send the VICA company either
500 chickens or a couple of boxes of Magic: The Gathering collectible
trading cards. Cool charge card.
Elisabeth R Higgins
[A bunch of stuff snipped about how this guy totally inspired every
movie ever made]
...which is really coincidental because I have been VERY disturbed of
late because I am being PLAIGARIZED BY THE WEEKLY WORLD NEWS.
Item 1: Several months ago, I made the decision to have print a
hard-hitting editorial for my newsletter that I would print on the front
page. That article was to be titled (banner headline) "Fluffy Bunnies
Are Cute"
About a month later, I picked up a WWN, the one with "12 US Senators are
Space Aliens," and in there was an article about how this one guy shot
and killed another guy in an argument over whether baby rabbits or
lampreys or something were cuter!
Item 2: Recently, I wrote the following Post-It(TM) Novel(TM):
She turned the string of soft grey stones over and over in her hand like
a rosary, never realizing that each innocuous orb was a gallstone he'd
passed while chanting her name like a mantra.
In the current WWN is a story about how this woman filed for divorce
because her husband gave her a necklace of gallstones!
You were all so supportive with your advice on the C&S shirts, I was
wondering if I, too, could get some free legal advice and/or emotional
support.
I am really cute, if that helps you decide.
Your Best Friend,
I Was Their Lesbian Egg!
Barry Merriman
>
> -- If Everett is right then there must be a vast multitude
> (albeit very small percentage) of worlds of unimaginable
> frightfulness (far worse than Auschwitz) which are no
> less real than this particular branch of the Universal
> wavefunction. I agree the case for the MWI is compelling,
> but unlike some of its enthusiastic supporters, I profoundly
> hope we are wrong: its implications are dreadful.
> Dave Pearce
> dav...@mdjf.demon.co.uk
This gives an interesting twist on Nietsche's theory of eternal
recurrence. He was plagued by the idea that in a finite universe
with infinite time, every thing would be played out repeatedly---so
every mistake you make you make infinitely many times, in
serial. Now, with many worlds, you can make every mistake
infinitely many times in parallel!
Peter Norton
>car...@marie.mit.edu (Sean Carroll) writes:
>>pfa...@isr.harvard.edu (David M. Pfarrer) writes:
>>>I've been looking at F.J. Tiplers "The Physics of Immortality."
>>Honestly, from the little I have heard, it is unlikely that the work
>>on immortality would be taken at all seriously by most physicists.
>>
>>--Sean
"Eternity (Immortality) is not a long time,
it has nothing to do with time."
-Joseph Campbell
"Time and space are modes by which we think,
they are not conditions in which we live."
-Albert Einstein
Physicists needn't worry about taking such ideas such as QM interpretations,
and life beyond time and space, seriously, since they can have only a negative
to zero impact on their funding and prestige, since Physics is inherently
meaningless.
All meaning is left as an excercise for the student.
"This truth is beyond extension or diminution in time or space,
in it, one thought is ten thousand years."
-Sengtsan
"Fools will laugh, but the Wise will understand." (why am I laughing?)
Jack Sarfatti
I did not "lay off" the women in my classes. Also I did not "lay all" the
women in my classes. If you read carefully what I wrote I explicitly said
I did not make love to any women in my classes, but did to coeds who were
not in my classes. And yes, at that time I, like most young studs, was
most definitely an unabashed sexist bastard. I am not a sexist bastard now
however! That was 25 years ago remember!!!
Jack Sarfatti
>
>I am really cute, if that helps you decide.
>
OK, let's have a drink.
Jack Sarfatti
>: >Do you know Skip Williamson? I got drunk with him at a party on Saturday.
>: >He just turned 50.
>
>: I nevah hoid of da bum!
>
>Well, from what I could tell, he was a cartoonist working at Playboy with
>ol' Pope R.A.W. and they are pretty good friends. Oh well, I once had to
>take care of Mr. Wilson's $142.60 bar tab, so I've got that to name drop
>about.
>
>: The Curse of SAR is upon you! Sweet Dreams! :-<
>
>Does this mean I'll get to pen the storyline for an upcoming movie called
>Ghostbusters of the Third Kind? Will I have any input on David Lynch's
>next project? Or will I just move to Seattle and steal all the marijuana
>people leave on Jimi Hendrix's grave? If so, then I accept.
I know a producer looking for good scripts. I like your title! Let's
see the rest of it.
Lupus Yonderboy
>[A bunch of stuff snipped about how this guy totally inspired every
>movie ever made]
What you say is nonsense. <====--- This is Note Number One
>...which is really coincidental because I have been VERY disturbed of
>late because I am being PLAIGARIZED BY THE WEEKLY WORLD NEWS.
See Note Number One.
>About a month later, I picked up a WWN, the one with "12 US Senators are
>Space Aliens," and in there was an article about how this one guy shot
>and killed another guy in an argument over whether baby rabbits or
>lampreys or something were cuter!
I thought you didn't read WWW? Oh wait, that was someone else.
>Item 2: Recently, I wrote the following Post-It(TM) Novel(TM):
A very novel concept indeed... <===--- This is Note Number Two
>She turned the string of soft grey stones over and over in her hand like
>a rosary, never realizing that each innocuous orb was a gallstone he'd
>passed while chanting her name like a mantra.
See not number one. See note number two.
>In the current WWN is a story about how this woman filed for divorce
>because her husband gave her a necklace of gallstones!
Coincidence or FREAKY CONSPIRACY TO IMPURIFY OUR BODILY FLUIDS..??
You make the call, right after this commercial from Big Blue.
>You were all so supportive with your advice on the C&S shirts, I was
>wondering if I, too, could get some free legal advice and/or emotional
>support.
Joel? Is that you? Nah....
>I am really cute, if that helps you decide.
Not really.
>Your Best Friend,
>I Was Their Lesbian Egg!
Please. You must use the very confusing and obscure acronym
motss so you can feel smart when people ask you what it means.
In fact, I think all of my future posts may or may not be done
totally in acronyms, or as that paragone of virtue Chrissy Snow
said:
"You can't give an IOU to the UPS for a COD! They'll call
the FBI!"
-- Chrissy
-- The Fake Yonderboy
Elisabeth R Higgins
>Thus spake erh...@lookout.mtt.it.uswc.uswest.com (Elisabeth R Higgins):
>>I Was Their Lesbian Egg!
>
>Please. You must use the very confusing and obscure acronym
>motss so you can feel smart when people ask you what it means.
>In fact, I think all of my future posts may or may not be done
>totally in acronyms, or as that paragone of virtue Chrissy Snow
>said:
>
>"You can't give an IOU to the UPS for a COD! They'll call
> the FBI!"
>
> -- Chrissy
> -- The Fake Yonderboy
Well, it IS an obscure anagram. Is that elitist and erudite enough for
ya? See, I went to a STATE college and you know how insecure we can be.
*eye twitch* Dang, and there's that delphi address, too. Ummmm...
COBRA=Consolidated Omnibus Benefits Reconciliation Act
ZIP=Zoning Improvement Plan
There. I feel cooler already.
YBF<
Liberating Geishas, eh?
Michael Clive Price
Date: Tue, 23 Aug 94 21:52:56 GMT
Organization: NoneLines: 65
Dave Pearce:
> If Everett is right then there must be a vast multitude
> (albeit very small percentage) of worlds of unimaginable
> frightfulness (far worse than Auschwitz) which are no
> less real than this particular branch of the Universal
> wavefunction. I agree the case for the MWI is compelling,
> but unlike some of its enthusiastic supporters, I profoundly
> hope we are wrong: its implications are dreadful.
It's true that there will be many worlds of unimaginable frightfulness
and injustice, just as there will be others of peace and great serenity,
but then human affairs have never been a concern of the universe. There
are two reasons (that I can think of) why this might be depressing.
First is because of the implied shrinking of our role in the universe.
I expect we'll get used to that, just as we have to the displacement of
the Earth, then the Sun and later the Milky Way from the centre of the
cosmos. Now our cosmos has been put in its place, amongst its Everett-
neighbours. I find this immensity humbling, rather than depressing.
Second is the apparent loss of free-will, since all acts of will are
realised. I don't believe that this removes any moral imperative from
our actions. Here's why:
*******************
Q21 Does Many-Worlds allow free-will?
---------------------------------
Many-Worlds, whilst deterministic on the objective universal level, is
indeterministic on the subjective level so the situation is certainly
no better or worse for free-will than in the Copenhagen view.
Traditional Copenhagen indeterministic quantum mechanics only slightly
weakens the case for free-will. In quantum terms each neuron is an
essentially classical object. Consequently quantum noise in the brain
is at such a low level that it probably doesn't often alter, except very
rarely, the critical mechanistic behaviour of sufficient neurons to
cause a decision to be different than we might otherwise expect. The
consensus view amongst experts is that free-will is the consequence -
insofar as it is not an illusion which is a perfectly acceptable way of
viewing it - of the mechanistic operation of our brains, the firing of
neurons, discharging of synapses etc and fully compatible with the
determinism of classical physics.
Nevertheless, some people find that with all possible decisions being
realised in different worlds that the prima facia situation for free-
will looks quite difficult. Does this multiplicity of outcomes destroy
free-will? If both sides of a choice are selected in different worlds
why bother to spend time weighing the evidence before selecting? The
answer is that whilst all decisions are realised, some are realised more
often than others - or to put to more precisely each branch has its own
weighting or measure which enforces the usual laws of quantum
statistics.
The measure is supplied by the mathematical structure of Hilbert spaces.
Every Hilbert space has a norm, constructed from the inner product, -
which we can think of as analogous to a volume - which weights each
world or collection of worlds. A world of zero volume is never
realised. Worlds in which the conventional statistical predictions
consistently break down have zero volume and so are never realised.
(See "How do probabilities re-emerge within Many-Worlds?") Thus our
actions, as expressions of our will, correlate with the weights
associated with worlds. This, of course, matches our subjective
experience of being able to exercise our will, form moral judgements and
be held responsible for our actions.
*******************
Mike Price pr...@price.demon.co.uk
Jack Sarfatti
>
>Jack Sarfatti:
>> Not so fast, Mike. Bohm's paradigm is totally consistent with
>> an effective many-worlds quantum cosmology in which the actual
>> particles and fields of the universe are in one of the branches.
>
>Not in Feynman's opinion.
Please be specific - details???
>Nor Bohm's! (And I have heard Bohm speak about many-worlds.)
I was a Research Fellow under Bohm at Birkbeck 1971-2 so I would like to
hear what you heard Bohm say about many-worlds and when he said it. But
my point here is that if you read Undivided Universe it is perfectly
obvious that Bohm's interpretation in which all the branches are objectively
real though most are "empty" has all the virtues of traditional many-worlds
without the vices. The empty branches of the wave function of the universe
are simply objective possibilities which can influence the actual stuff
of the world (particles and fields - at least at low energy) upon coherent
recombination should environmental correlations permit for some subsystem etc.
You might say that the empty branches are patterns in universal mind-stuff -
which can interact with matter-stuff under suitable conditions. No one
disagrees that the many branches exist in some sense, but what is their
precise ontology? Bohm's version has an answer which agrees with classical
intuition once one is ready to throw out retarded causality as an absolute
truth, rather than as a good approximation under many ordinary conditions.
>
>I suppose Rabbi Yeshua was a many-worlds Bohmite, eh?
"Rabbi Yeshua" is the Hebrew name for Jesus Christ. So, is there some deep
meaning to your question? Did the Holy Spirit from the future reach back in
time from Tipler's Omega Point into your brain and force you to utter those
words? Yes, if Bohm's version is the correct one... :-) If orthodox quantum
mechanics is correct,then, by Eberhard's theorem, the Holy Spirit could do no
such thing! So the issue is of some practical importance politically let us say.
>
>Mike Price pr...@price.demon.co.uk
>
Jack Sarfatti
>It's true that there will be many worlds of unimaginable frightfulness
>and injustice, just as there will be others of peace and great serenity,
>but then human affairs have never been a concern of the universe. There
>are two reasons (that I can think of) why this might be depressing.
>
>First is because of the implied shrinking of our role in the universe.
>I expect we'll get used to that, just as we have to the displacement of
>the Earth, then the Sun and later the Milky Way from the centre of the
>cosmos. Now our cosmos has been put in its place, amongst its Everett-
>neighbours. I find this immensity humbling, rather than depressing.
>
>Second is the apparent loss of free-will, since all acts of will are
>realised. I don't believe that this removes any moral imperative from
>our actions. Here's why:
Rejoice - Frank Tipler in The Physics of Immortality (Doubleday 94) shows
that Price, Weinberg et-al are mistaken - and good thing too! :-)
Velia Tanner and Friends
>And yes, at that time I, like most young studs, was
^^^^^^^^^^^^^^^^^^^^^
>most definitely an unabashed sexist bastard.
Altogether now ladies: EEEEEEEWWWWWWWW!!!
--
=========================================================
VE...@NETCOM.COM | Dark Seraph explains it all 2U
"What if I told you it was Magic?"
-- Highlander, Unholy Alliance II
=========================================================
mark a friesel
erh...@lookout.mtt.it.uswc.uswest.com (Elisabeth R Higgins) wrote:
> I am really cute, if that helps you decide.
>
Hey! Dark hair? 5'2" or so? fair skin? Good build? Out of Dallas? Is
Elisabeth Higgins a pseudonym? Forget these guys - let's start talking
Real Science!!
In Hilbert, Riemann, or in Banach space
Let superscripts and subscripts go their ways
Our asymptotes no longer out of phase
We shall encounter, counting, face-to-face.
I see the eigenvector in thine eye
I hear the tender tensor in thy sigh
Bernoulli would have been content to die
Had he but known such A-squared cos 2-phi!
Stan Lem
(recited with deep passion and profound despair)
Mark A. Friesel
(509) 375-2235
e-mail: ma_fr...@pnl.gov
'We're...OFF to see the wizard!'
(but then, we'd have to be)
Michael Clive Price
>> Not in Feynman's opinion.
> Please be specific - details???
Feynman believed in many-worlds. See pages 170-1 of FJTipler's latest
(eccentric) book where he reports on L David Raub's survey of leading
theorist's views on Everett.
>> Nor Bohm's! (And I have heard Bohm speak about many-worlds.)
>
> I was a Research Fellow under Bohm at Birkbeck 1971-2 so I would
> like to hear what you heard Bohm say about many-worlds and when
> he said it.
He did not say very much. Dismissed it as SF or Star Trek stuff,
without rational analysis. Forget the exact phrase - it was over 10
years ago - but you get the general idea. c1982, Chelsea College,
London.
> But my point here is that if you read Undivided Universe it is
> perfectly obvious [...that only Sarfatti is right...]
Please, start don't sounding like Budnik. He proceeds all his
falsehoods with the word "obvious". It's a code word that means
"I have not bothered to analysis this statement."
> No one disagrees that the many branches exist in some sense,
If you think this you are really out of touch. *Lots* of people
disagree that they exist in *any* sense. They're wrong, but that's
another matter.
> but what is their precise ontology?
They're all real.
Mike Price pr...@price.demon.co.uk
Peter Norton
>In <CuvMu...@world.std.com> ki...@world.std.com (James "Kibo" Parry) writes:
[...]
>State College professor seduces the young coed is based directly on Fred Alan Wolf's
>and my activities as Physics Professors at San Diego State where we made love to lots
>of very pretty coeds, - though not ones in our classes -often two or more in one day
>- ah youth! I was in my late 20's when I was a prof there and was not much older
>than the coeds.
>
>> Please tell us more.
>
>San Diego State is loaded with gorgeous friendly girls -- or was in the 60's! -
>blondes, redheads, brunettes, with fabulous Play Boy Bunny figures, generally took me
>about an hour from first meeting into bed. This was pre-herpes, pre-AIDS, I never
>even got VD - those were they days, my friend, we thought they'd never end! But
>they did! The only thing I regret about quitting my job at San Diego State -
>is the girls! Fred shot a film with a bunch of naked really spectacular coeds and me
sigh. Human, all too Human. Ecce Homo!
Once upon a time, long long ago, in a land far far away, there lived
a young prince who had the good fortune to be able to f*ck his brains
out before the age of 25 since his father gave him his own harem. As a
result, he was able to grow up a little beyond the chimpanzee level.
Once upon a time, long long ago, in a land far far away, there lived
a young woman who had the good fortune to be able to f*ck her brains
out before the age of 25, since she was forced to be a prostitute. As a
result, she was able to grow up a little beyond the chimpanzee level.
The world is on fire, say I. And with what is it on fire?
Peter Norton
>
>But, realizing that it is only the Universe evolving in its self-understanding
^^^
What an embarassing slip! Of course, I meant to say:
But, realizing that it is only a Universe evolving in its self-understanding
^
How quickly we forget!
Peter Norton
>ba...@arnold.math.ucla.edu (Barry Merriman) writes:
>>
>>sarf...@ix.netcom.com (Jack Sarfatti) writes:
>>>
>The films Ghost Buster's, Back From The Future, Close Encounters of The Third
>Kind, Peggy Sue Got Married and Time Bandits might not have even been conceived
>were it not for my activities at Esalen in Big Sur in mid 70's and my
>connections to Francis Ford Coppola's circle at that time. Dancing Wu Li
>Masters would not have been written and Tao of Physics might not have gotten
>published. I have certainly "made a difference" in pop culture - and now with
>internet, CD and new TV I am just getting started. You ain't seen nothin yet! :-)
No doubt you have made a difference. But don't let it go to your head,
(literally). That way madness lies.
Here is some advice that works for me, that I humbly offer:
"That we move and understand all things, is ignorance.
That things evolve and understand themselves is enlightenment."
-Eihei Dogen
i.e.:
"That we think we are studying and learning and creating, is just a
limited, vain, self-centered perspective, that could easily lead to
delusions of grandeur and then to real psychosis. Especially when the
synchronicities start coming fast and furious. e.g. the 'spiritual inflation'
syndrome, which causes some folks to loudly 'witness' on BART day after day.
or e.g. the Plutonium Atom Totality, or e.g. Time has Inertia,
or e.g. Terence McKenna's 'True Hallucinations' etc. etc.
But, realizing that it is only the Universe evolving in its self-understanding
through us (as convenient fictions of self-identity) is the way to
maintain sanity, good humor, and freedom from persecution by those still
trapped in the narcissistic dream of ego, which they will defend at all costs."
They don't call it a 'razor's edge' for nuthin.
If you ever need a real friend to guide you through the Chaos of Many Minds,
and the Chaos of Many Worlds, check out the I Ching (seriously).
Cheers.
Jack Sarfatti
pno...@beaux.atwc.teradyne.com (Peter Norton) writes:
>
>sarf...@ix.netcom.com (Jack Sarfatti) writes:
>>ba...@arnold.math.ucla.edu (Barry Merriman) writes:
>>>
>>>sarf...@ix.netcom.com (Jack Sarfatti) writes:
>>>>
>>The films Ghost Buster's, Back From The Future, Close Encounters of The Third
>>Kind, Peggy Sue Got Married and Time Bandits might not have even been conceived
>>were it not for my activities at Esalen in Big Sur in mid 70's and my
>>connections to Francis Ford Coppola's circle at that time. Dancing Wu Li
>>Masters would not have been written and Tao of Physics might not have gotten
>>published. I have certainly "made a difference" in pop culture - and now with
>>internet, CD and new TV I am just getting started. You ain't seen nothin yet! :-)
>
>No doubt you have made a difference. But don't let it go to your head,
>(literally). That way madness lies.
Too late! :-)
>i.e.:
>
>"That we think we are studying and learning and creating, is just a
>limited, vain, self-centered perspective, that could easily lead to
>delusions of grandeur and then to real psychosis. Especially when the
>synchronicities start coming fast and furious. e.g. the 'spiritual inflation'
>syndrome, which causes some folks to loudly 'witness' on BART day after day.
>or e.g. the Plutonium Atom Totality, or e.g. Time has Inertia,
>or e.g. Terence McKenna's 'True Hallucinations' etc. etc.
I would not compare Terence to Ludwig and Alex.
>
>But, realizing that it is only the Universe evolving in its self-understanding
>through us (as convenient fictions of self-identity) is the way to
>maintain sanity, good humor, and freedom from persecution by those still
>trapped in the narcissistic dream of ego, which they will defend at all costs."
Narcissism is comedy.
>They don't call it a 'razor's edge' for nuthin.
Tell it to OJ!
>
>If you ever need a real friend to guide you through the Chaos of Many Minds,
>and the Chaos of Many Worlds, check out the I Ching (seriously).
>
>Cheers.
>
>
I wrote the I Ching in one of my Future Lives and then transmitted it back
in time.
Bob Ezergailis
SA>Message-ID: <3396a6$4...@ixnews1.ix.netcom.com>
SA>Not so fast, Mike. Bohm's paradigm is totally consistent with an effective
SA>many-worlds quantum cosmology in which the actual particles and fields of
SA>the universe are in one of the branches.
In the ocean of everything that is there is wave tree and upon one of
its more prominent branches sits SAR.... ;^)
Apart from the fact that the tree with its branches is a "venerable"
cosmological symbol from thousands of years ago, the fact is that waves
do not branch. I would not even want to say that superstrings "branch".
I contend that the "particles and fields", as well as the apparent
"branching" logic are a mind product resulting from the limitations of
the mechanisms of observation and how they are anthropocentrically
interpreted. (As useful as those terms sometimes are.) The design of
new, technical, means of observation is probably quite limited by the
nature of the natural physical structure of homo sapiens who cannot
build mechanisms from non observables (and non manipulables that
become something else when observed or manipulated). A fundamental
limitation that all human built mechanisms for observing the universe
are necessarily built from the same kind of stuff that humans are
comprised of, means that everything we do might be very misleading as to
the real nature of the universe. We might be totally fooled by design,
and would we ever know whether we are or are not thus fooled ?
The only way that saying that the "actual particles and fields of the
universe are in one of the branches" makes sense is as a categorization.
It is not unlike saying carbon is one of the branches within organisms.
We are habituated into thinking in exactly that way. It is in fact that
way only in a formula giving proportions for the basic constituents (as
we understand and differentiate them). I am saying that "the actual
particles and fields of the universe" are more likely not isolated and
segregated in terms of a larger space-time topology, as a kind of
ghetto at the fringes of which the Earther's dwell, even if there is
other unknown (and wierder) stuff scattered and variably concentrated
here and there somewhere out there. The latter is very likely. Not all
universes are necessarily built of the same kind of observables as this
one is, and not all of this universe is in fact comprised of the
observables.
* SLMR 2.1a * Chaos factors: It was only a tiny electronic impulse.
James Kibo Parry
Jack Sarfatti <sarf...@ix.netcom.com> wrote:
> I wrote the I Ching in one of my Future Lives and then transmitted it back
> in time.
Wile writing it, were you consulting random passages from Philip K. Dick's
"The Man In The High Castle"?
(Look, mommy, I made an obscure funny! So obscure that it's not worth
explaining!)
-- K.
Andy Boden
[clippage]
> If you think this you are really out of touch. *Lots* of people
> disagree that they exist in *any* sense. They're wrong, but that's
> another matter.
>
Mike,
Since you and I have had parts of this discussion off line, I
*think* I understand the sense in which you unequivocally support the
Everett interpretation. Nevertheless, public statements like these
that really *can't* be proven experimentally probably ought to be
couched as supposition (at least in the realm of scientific
discussion). One thing that tends to raise the red flag on Everett in
the minds of minimalist-leaning fence-sitters like myself is just how
dogmatic Everett evangelists like you or Ron are despite the lack of
tangible experimental proof for your positions.
My impression is that most people believe that the jury's still out
on Everett, and I think you'll be a lot more persuasive if you aren't
quite so strident in your support of positions that you can't prove.
Best wishes.
- A.B.
--
"...it doesn't matter how beautiful your theory is, it doesn't matter
how smart you are -- if it doesn't agree with experiment, it's wrong."
- R.P. Feynman
Bob Ezergailis
<3396a6$4...@ixnews1.ix.netcom.com>:
SA>Not so fast, Mike. Bohm's paradigm is totally consistent with an effective
SA>many-worlds quantum cosmology in which the actual particles and fields of
SA>the universe are in one of the branches.
I replied:
In the ocean of everything that is there is wave tree and upon one of
its more prominent branches sits SAR.... ;^)
---------
This is the likely basis of a deja-vu, in mid 1993, of an experience of
"Jack Sartree" direct from the Cafe Trieste, via "the spiritual
switchboard". "That's it !"
* SLMR 2.1a * Into the depths of the night that only the shadows know.
Karl Kluge
It's not *that* obscure. I suspect that back in the early '80s, before the
information superhighway became clogged with the information age equivalent of
the guy doing 5 mph under the speed limit in the left lane with his turn
signal on, pretty much everyone reading netnews would have understood the
reference.
Karl "Good thing my middle name's not Kibo" Kluge
Ted Frank
>Jack Sarfatti <sarf...@ix.netcom.com> wrote:
>> I wrote the I Ching in one of my Future Lives and then transmitted it back
>> in time.
>
>Wile writing it, were you consulting random passages from Philip K. Dick's
>"The Man In The High Castle"?
You mean "White Castle," right?
--
ted frank "Yeah, I'm moving in September." "Oh, going to the North
Side?" "No, no, still in Hyde Park. Just a few blocks
north of where I am now. The trend is right, though." "I
wouldn't keep doing it a few blocks at a time."
Roberta J. Barmore
: In article <33jae9$5...@ixnews1.ix.netcom.com>,
It's not *that* obscure. Besides, we don't live there anymore! Do
you have any idea how hard it was to get the groceries up there? Half
the time, the milk had turned all blinky by the time we got it to the
"castle." It was dank, drafty, and cold, too!
I must admit, the all of the free pizza from Mitsubishi* ("45 minutes
or we kill ourselves in a ceremonial manner!") was kind of nice when we
lived there, though it had usually gone cold by the time it *did* arrive...
The other day, I did recieve the entire script of my future life,
which I'd sent back from a far distant future. I laughed myself
silly! My judgement never does get any better....
--bobbi
(Who has given up on an ibo-prefix, and never had a Kibo-number at
all. And my Kibo *Factor* is a *secret!*)
_____________________
*Beat *that* for obscurity--a weak bilingual pun! Who was Horselover
Fat, anyway?
Michael Clive Price
Date: Sun, 28 Aug 94 10:47:33 GMTLines: 44
I said
>> [The other Everett-worlds are] all [as] real [as ours].
Andy Bode:
> One thing that tends to raise the red flag on Everett in the
> minds of minimalist-leaning fence-sitters like myself is just
> how dogmatic Everett evangelists like you or Ron are despite
> the lack of tangible experimental proof for your positions.
Would you have had the same minimalist-leaning reactions to someone
making similar statements about atoms existing in the 19th century?
People got very worked up about the existence of atoms, just as we do
about the wavefunction today. Were the atomists wrong to put their case
strongly against the positivists?
To an Everettist like myself the existence of other quantum worlds is
as confirmed as the existence of atoms or quarks are today. I'm sorry
that that appears dogmatic, but I think it's more the insidious effect
of 70 years of rampant positivism rather any weakness in my position.
> My impression is that most people believe that the jury's still out
> on Everett, and I think you'll be a lot more persuasive if you aren't
> quite so strident in your support of positions that you can't prove.
Do you think the existence of atoms is proved? (If you don't what
experiment is sufficient to prove the existence of *anything*?)
Mike Price pr...@price.demon.co.uk
lmerkel on BIX
I always wondered if the book about the Grasshopper in that
novel was a forward reference to the Kung Fu series, which
came, of course, later.
-- Lee Merkel
Jack Sarfatti
predictions in Physics of Immortality. However, I think his predictions
will also work in Bohm's version which has many worlds of ontologically
real wave function branches only one of which is actually occupied by
"low energy" particles and gauge fields.
Ben Weiner
ki...@world.std.com (James "Kibo" Parry) writes:
>Jack Sarfatti <sarf...@ix.netcom.com> wrote:
>> I wrote the I Ching in one of my Future Lives and then transmitted it back
>> in time.
>Wile writing it, were you consulting random passages from Philip K. Dick's
>"The Man In The High Castle"?
>(Look, mommy, I made an obscure funny! So obscure that it's not worth
>explaining!)
> -- K.
That's not that obscure.
[I sense a lack of confidence in the Wisdom of the Net, Kibo. Shame! Shame!]
Definitely not as obscure as "It furthers one to cross the great water."
Or "One sees the wagon dragged back, the oxen halted, a man's nose and hair
cut off. Not a good beginning, but a good end."
-----------
hexagram 65: Rolling Thunder. "Destruction will fall from the air."
al jackson
>From: kck...@krusty.eecs.umich.edu (Karl Kluge)
>Subject: Re: F.J. Tipler: what's his reputation?
>Date: 26 Aug 1994 20:29:52 GMT
All up and down the information superhighway:
Bozo Lights.
Andy Boden
> <33l2u9$j...@elroy.jpl.nasa.gov>
> Date: Sun, 28 Aug 94 10:47:33 GMT
> Organization: None
> Reply-To: pr...@price.demon.co.uk
> X-Newsreader: Simple NEWS 2.0 (ka9q DIS 1.24)
> Lines: 44
>
> I said
> >> [The other Everett-worlds are] all [as] real [as ours].
>
> Andy Bode:
> > One thing that tends to raise the red flag on Everett in the
> > minds of minimalist-leaning fence-sitters like myself is just
> > how dogmatic Everett evangelists like you or Ron are despite
> > the lack of tangible experimental proof for your positions.
>
> Would you have had the same minimalist-leaning reactions to someone
> making similar statements about atoms existing in the 19th century?
Absolutely. Just because we have the benefit of hindsight doesn't
change the rules by which science is (or should be) conducted. One
thing I agree with Paul Budnik about is what separates philosophy from
science is the litmus test of experiment. Before the experimental
evidence that demonstrated the existance of atoms, the atomic theory
was just another predictive theory -- useful, but to be believed
*exactly* as far as it could be tested.
> People got very worked up about the existence of atoms, just as we do
> about the wavefunction today. Were the atomists wrong to put their case
> strongly against the positivists?
I certainly don't have any problems with folks who are proponents of
given untested theories -- as long as they have an appreciation of
what is and what is not proven by experiment and will couch their
arguments with that caveat. (I wasn't around to hear the tenor of the
arguments in the atomic theory case, so I can't really comment
directly.) However, when people overstate the case for their pet
theory (as I think you and Ron do -- no offense intended), they lose
sight of the objectivity that science is supposed to embody -- at
least that's how I see it.
> > My impression is that most people believe that the jury's still out
> > on Everett, and I think you'll be a lot more persuasive if you aren't
> > quite so strident in your support of positions that you can't prove.
>
> Do you think the existence of atoms is proved? (If you don't what
> experiment is sufficient to prove the existence of *anything*?)
I'm going to let this slide -- there's no need to belabor the obvious.
>
> To an Everettist like myself the existence of other quantum worlds is
> as confirmed as the existence of atoms or quarks are today. I'm sorry
> that that appears dogmatic, but I think it's more the insidious effect
> of 70 years of rampant positivism rather any weakness in my position.
>
Well, if you can point me to a Phys Rev or Nuc Phys paper that does
experimentally (and unequivocally) demonstrate the existance of other
quantum worlds then you're right, I'm wrong, and you have my most
sincere public apology. But since we've had similar discussions a few
months ago, I don't think you can. Until that time, I don't believe
you're justified in making the claim that the existance of other
quantum worlds is on the same scientific foundation as atoms or
quarks.
The arguments for the Everett interpretation are indeed powerful and
compelling. But until they are on a firm experimental foundation,
they remain in the realm of belief, and intellectual honesty demands
that you be forthright about their speculative nature. You seem like
a smart guy -- I don't think it weakens your advocacy to be
forthcoming about the status of the Everett interpretation, and it
makes the cynics among us more comfortable that your arguments are
more reasoned and less dogmatic.
(In case you're offended, I don't mean to attack your integrity or
intelligence. I just feel your zeal for your position has overcome
your better scientific judgement.) Sincere best wishes in your
pursuits.
Peter Norton
>> If Everett is right then there must be a vast multitude
>> (albeit very small percentage) of worlds of unimaginable
>> frightfulness (far worse than Auschwitz) which are no
>> less real than this particular branch of the Universal
>> wavefunction. I agree the case for the MWI is compelling,
>> but unlike some of its enthusiastic supporters, I profoundly
>> hope we are wrong: its implications are dreadful.
>
>It's true that there will be many worlds of unimaginable frightfulness
>and injustice, just as there will be others of peace and great serenity,
Which is all the more reason to pay careful attention to how you are
creating your world. Not conscious attention, per se, just attention.
>but then human affairs have never been a concern of the universe.
At least, not until it sees that it is a concern of ours. That is when
the synchronicities start to snowball. Attention is reciprocal.
Ignore it, and it will ignore you. Pay attention, and you will be paid
attention.
By the way, it is interesting to think that science is inherently incapable
of investigating the phenomenon of synchronicity, since, by definition, it
is impossible to do a controlled, repeatable, experiment with a synchronicity.
Therefore, they do not exist. OK? OK?
Anybody know any good tunes to whistle in the dark?
Cheers.
---
"Bohm + Ockham = Everett" (Mike Price)
"One sleeps much more soundly if one does not think too hard about the
theory of the I Ching." (Carl Jung)
"Time and space are modes by which we think, they are not conditions in
which we live." (Einstein)
"At first, there is no QM interpretation problem (Bohr),
then there is (Bohm),
then there isn't (Everett)."
"Then there is (Budnik),
Then there isn't (Price),
Then there is (Budnik),
Then there isn't (Price),
Then there is (Budnik),
Then there isn't (Price),
Then there is (Budnik),
Then there isn't (Price),
Then there is (Budnik),
Then there isn't (Price),
Then there is (Budnik),
Then there isn't (Price),
..."
Peter Norton
>pr...@price.demon.co.uk (Michael Clive Price) writes:
>[clippage]
>> If you think this you are really out of touch. *Lots* of people
>> disagree that they exist in *any* sense. They're wrong, but that's
>> another matter.
>>
>> They're all real.
>>
>> Mike Price pr...@price.demon.co.uk
>
> My impression is that most people believe that the jury's still out
>on Everett, and I think you'll be a lot more persuasive if you aren't
>quite so strident in your support of positions that you can't prove.
>Best wishes.
>
>how smart you are -- if it doesn't agree with experiment, it's wrong."
>
> - R.P. Feynman
Many, many, many throughout history have done the experiment.
Everett is right.
Unfortunately, their results are not publishable in conventional format.
They don't even really understand them themselves. I can only refer you to
the procedural manuals by means of which you can replicate the results for
yourself:
"How to Meditate" by Laurence LeShan.
"The Lazy Man's Guide to Enlightenment" by Thaddeus Golas
etc. etc. etc.
The only required equipment is the finest observational instrument in
the known universe designed especially for the investigation of the
measurement paradox, e.g. the human brain (with slight custom modifications,
which can be a little painful at first, but you get used to it, if you
survive the 'operation').
Cheers.
---
"When Mind exists undisturbed in itself, things cease to exist in the old way."
-Sengtsan
"The essence of Mind is apart from all observation."
-Hui Neng
Erik Max Francis
> The only required equipment is the finest observational instrument in
> the known universe designed especially for the investigation of the
> measurement paradox, e.g. the human brain (with slight custom modifications,
> which can be a little painful at first, but you get used to it, if you
> survive the 'operation').
Hey, that's great. Congratulations. But it's not science.
Erik Max Francis, &tSftDotIotE ...!uuwest!alcyone!max m...@alcyone.darkside.com
USMail: 1070 Oakmont Dr. #1 San Jose, CA 95117 ICBM: 37 20 N 121 53 W _
H.3`S,3,P,3$S,#$Q,C`Q,3,P,3$S,#$Q,3`Q,3,P,C$Q,#(Q.#`-"C`- ftmfbs kmmfa / \
Omnia quia sunt, lumina sunt. ("All things that are, are lights.") -><- \_/
Robert Firth
>Hey, that's great. Congratulations. But it's not science.
That's right. The province of science is whatever can be observed
inside the Cave.
Nate Zelnick
>*Beat *that* for obscurity--a weak bilingual pun! Who was Horselover
>Fat, anyway?
Damn, I had that information in my VALIS, but I left it in the back of my
friend Tim Archer's car and now he's off in the desert rooting for
mushrooms...
Nate "not to be outdone by bad puns or obscurity" Zelnick
--
Nate Zelnick
nzel...@access.digex.net
no wife, no horse, no mustache
Jim Carr
has an excellent article by Ivars Peterson on the physics issues at the
intersection of nuclear and particle physics that will be studied at
CEBAF with 1-6 GeV electron and photon beams. It would seem to come
from his coverage of the April APS meeting and the recent few-body
conference at CEBAF.
(CEBAF is the Continuous Electron Beam Accelerator Facility located
in Newport News, VA, on the former site of SREL for any oldtimers.
Continuous means the beam pulses come at RF rates, which makes
coincidence experiments where you detect the scattered electron and
a newly produced pion, for example, and use the electron to tell you
the details of the momentum and energy transferred to the target.)
The unidentified picture with the article appears to be one of the
six sections of the CLAS (CEBAF Large Acceptance Spectrometer) that
will go in Hall B when complete in about 2 years. CEBAF has,
according to last reports, put beam on target in Hall C.
Except for the failure to mention the importance of hadronic probes
of some of the phenomena that occur in the nuclear environment, it is
a very good popular review of the physics issues to be addressed at
that facility over the next decade. I highly recommend it.
--
James A. Carr <j...@scri.fsu.edu> | Raw data, like raw sewage,
http://www.scri.fsu.edu/~jac | requires some processing before
Supercomputer Computations Res. Inst. | it can be spread around. The
Florida State, Tallahassee FL 32306 | opposite is true of theories.
Roberta J. Barmore
: In article <Cv7sv...@indy.net>, Roberta J. Barmore <rbar...@indy.net> wrote:
: >*Beat *that* for obscurity--a weak bilingual pun! Who was Horselover
: >Fat, anyway?
: Damn, I had that information in my VALIS, but I left it in the back of my
: friend Tim Archer's car and now he's off in the desert rooting for
: mushrooms...
Oh, *great!* Now I'll be dreamin' about electric sheep all week!
Your Ubik-quity amazes me, Nate....
I'll be over in DaVinciville with the rest of the Manics--look me up
net time you drop by the Alphane Moon!
--Bobbi
(I have no .sig. .Sigs can make you forget things, like what animal
has...ummm...STRIPES! Or even make you do awful things. .Sigs are bad;
I don't do .sigs.)
Peter Norton
>
>> The only required equipment is the finest observational instrument in
>> the known universe designed especially for the investigation of the
>> measurement paradox, e.g. the human brain (with slight custom modifications,
>> which can be a little painful at first, but you get used to it, if you
>> survive the 'operation').
>
>Hey, that's great. Congratulations. But it's not science.
Congratulations are premature, but thank you anyway.
I am merely extrapolating from the literature base and a few
preliminary, inconclusive results of my own. Sorry it sounds so definitive.
'Science' is in the eye of the scientist.
"'Science'" is in the eye of the funding agency.
>Omnia quia sunt, lumina sunt. ("All things that are, are lights.")
Is this a statement of fact? How do you know? Science? Experience?
Should I just believe it, or is there some experiment I could do?
If there is an experiment I could do, would that make it science?
Cheers.
---
"Light has no need of more Light."
- Krishnamurti
"O blinding Light, O Light that blinds, I cannot see, look out for me."
- Firesign Theatre
Joshua Rehman
Michael Clive Price
Date: Fri, 02 Sep 94 03:53:05 GMTLines: 98
Andy Bode:
> Before the experimental evidence that demonstrated the existence
> of atoms, [....]
Ah, so you do believe in the existence of atoms! As I do, I might add,
but my question was not rhetorical. If you can believe in atoms, why
then is belief in the existence of the wavefunction and the
wave-equation so preposterous, for which there is just as much (or more)
evidence?
> the atomic theory was just another predictive theory
> -- useful, but to be believed *exactly* as far as it could be tested.
Testing can be retrodictive as well as predictive. Explaining
retrodictive data is more convincing because there is less risk of
preconceived experimenter bias creeping into the data.
Einstein retrodicted the perihelion shift of Mercury for GR, which was
what convinced him. It convinced a lot people prior to 1919 or whenever
when the bending of light by predicted amount by the sun was (weakly)
confirmed.
Everett retrodicted all of quantum theory. Deutsch's test of Everett
is predictive. Every laboratory experiment in (say) spectroscopy (which
confirms the wave-equation) is a retrodictive test of Everett. That's
why I said:
>> To an Everettist like myself the existence of other quantum
>> worlds is as confirmed as the existence of atoms or quarks are
>> today.
because I am using retrodictive data whereas you are (apparently)
confining your attention to predictive data.
Mike Price pr...@price.demon.co.uk
Michael Clive Price
Date: Fri, 02 Sep 94 03:53:43 GMTLines: 67
Peter Norton:
> Anybody know any good tunes to whistle in the dark?
Try "Wonderful Copenhagen" by Hans Anderson. Lots of (other) people
seem to like it.
> "Then there is (Budnik),
> Then there isn't (Price),
> Then there is (Budnik),
> Then there isn't (Price),
> Then there is (Budnik),
> Then there isn't (Price),
> Then there is (Budnik),
> Then there isn't (Price),
> Then there is (Budnik),
> Then there isn't (Price),
> Then there is (Budnik),
> Then there isn't (Price),
> ..."
Aren't text editors fun!
BTW, Pete, I'd love to comment on the relationship between Everett and
the I Ching, but I couldn't find any refs to the latter in the Science
Citation Index :-)
Mike Price pr...@price.demon.co.uk
Michael Clive Price
******************************
Frequently Asked Questions about the Many-Worlds
or Relative State Formulation of Quantum Theory.
Answers compiled by Michael Clive Price
Comments to pr...@price.demon.co.uk
Last Modified: 25-September-1994
Contents:
1 What are the problems with quantum theory?
2 What is the Copenhagen interpretation?
3 What is many-worlds?
4 What is a "world"?
5 What is a measurement?
6 Why do worlds split?
7 When do worlds split?
8a What is sum-over-histories?
8b What is many-histories?
9 How many worlds are there?
10 Is many-worlds a local theory?
11 Is many-worlds a deterministic theory?
12 Is many-worlds a relativistic theory?
13 Is many-worlds (just) an interpretation?
14 What are the alternatives?
15 Is many-worlds testable?
16 Could previously separate worlds diverge rather than split?
17 What is many-minds?
18 Does many-worlds violate Ockham's Razor?
19 Does the multiplication of worlds violate conservation of energy?
20 How do probabilities emerge within many-worlds?
21 Does many-worlds allow free-will?
22 Why am I in this world and not another?
23 Can wavefunctions collapse?
24 Is physics linear?
25 Can we determine what other worlds there are?
26 Who was Everett?
27 Who believes in many-worlds?
28 Does the EPR experiment prohibit locality?
31 References and further reading
Q1 What are the problems with quantum theory?
------------------------------------------
Quantum theory is the most successful description of microscopic systems
like atoms and molecules ever, yet often it is not applied to larger,
classical systems, like observers or the entire universe. Many
scientists and philosophers are unhappy with the theory because it seems
to require a fundamental quantum-classical divide. Einstein, for
example, and despite his early contributions to the subject, was never
reconciled with assigning the act of observation a physical
significance, which QM requires. This contradicts the reductionist
ethos that, amongst other things, observations should emerge only as a
consequence of an underlying physical theory and not be present in the
axioms, as they are in the Copenhagen interpretation. Yet the
Copenhagen interpretation is the most popular interpretation of quantum
mechanics. (See "What is the Copenhagen interpretation?")
Q2 What is the Copenhagen interpretation?
--------------------------------------
An unobserved system, according to the Copenhagen interpretation of
quantum theory, evolves in a deterministic way determined by a wave
equation. An observed system changes in a random fashion,
instantaneously, with the probability of any particular outcome given
by the Born formula, determined by the wavefunction. This is known as
the collapse of the wavefunction. The problems with this approach are:
(1) The collapse is an instantaneous process across an extended
region ("non-local"). This is in conflict with relativity,
which states that no processes can be transmitted faster than
the speed of light. (Nevertheless it has been shown that no
information can be transmitted faster than light by the
collapse process).
(2) The idea of an observer having an effect on microphysics is
repugnant to reductionism and smacks of a return to pre-scientific
notions of vitalism. Copenhagenism is a return to the old
vitalist notions that life is somehow different from other matter,
operating by different laws from inanimate matter. The collapse
is triggered by an observer, yet no definition of what an
"observer" is available, in terms of an atomic scale description,
even in principle.
For these reasons the view has generally been adopted that the
wavefunction associated with an object is not a real "thing", but merely
represents our *knowledge* of the object. This approach was developed
by Bohr and others, mainly at Copenhagen in the late 1920s. When we
perform an measurement or observation of an object we acquire new
information and so adjust the wavefunction as we would boundary
conditions in classical physics to reflect this new information. This
stance means that we can't answer questions about what's actually
happening, all we can answer is what will be the probability of a
particular result if we perform a measurement. This makes a lot of
people very unhappy since it provides no model for the object.
It should be added that there are other, less popular, interpretations
of quantum theory, but they all have their own drawbacks, which are
widely reckoned more severe. Generally speaking they try to find a
mechanism that describes the collapse process or add extra physical
objects to the theory, in addition to the wavefunction. In this sense
they are more complex. (See "Is there any alternative theory?")
Q3 What is many-worlds?
--------------------
AKA as the Everett, relative-state, many-histories or many-universes
interpretation. Dr Hugh Everett III, its originator, called it the
relative-state metatheory or the theory of the universal wavefunction
[1], but, after DeWitt [4a],[5], it is generally called many-worlds
nowadays.
Many-worlds comprises of two assumptions and some consequences. The
assumptions are quite modest:
1) The metaphysical assumption: That the wavefunction does not merely
encode the information about an object, but has an observer-
independent objective existence. For an N-particle system the
wavefunction is a complex-valued field in a 3-N dimensional space.
In quantum field theory the state vector spans a space of an
indeterminate number of dimensions.
2) The physical assumption: The wavefunction obeys some standard
linear deterministic wave equation at all times. The observer
plays no special role in the theory and, consequently, there is no
collapse of the wavefunction. Measurement and observation are
modelled by applying the wave equation to the joint subject-object
system. For non-relativistic systems the Schrodinger wave equation
is a good approximation to reality. (See "Is many-worlds a
relativistic theory?" for the more general case.)
The rest of the theory is working out consequences of the above
assumptions. Some consequences are:
1) That each measurement causes a decomposition or decoherence of the
universal wavefunction into non-interacting and non-interfering
branches or worlds. History forms a branching tree which
encompasses all the possible outcomes of each interaction. (See
"Why do worlds split?" and "When do worlds split?") Every
historical what-if compatible with the initial conditions and
physical law is realised.
2) That the conventional statistical Born interpretation of the
amplitudes in quantum theory is *derived* from within the theory
rather than having to be *assumed* as an additional axiom. (See
"How do probabilities emerge within many-worlds?")
Many-worlds is a re-formulation of quantum theory [1], published in 1957
by Dr Hugh Everett III [2], which treats the process of observation or
measurement entirely within the wave-mechanics of quantum theory, rather
than an input an as additional assumption, as in the Copenhagen
interpretation. Everett considered the wavefunction a real object.
(Many-worlds is a return to the classical, pre-quantum view of the
universe in which all the mathematical entities of a physical theory are
real. For example, the electromagnetic fields of James Clark Maxwell
or the atoms of Dalton, were considered as real objects in classical
physics. Everett treats the wavefunction in a similar fashion. Everett
also assumed that the wavefunction obeyed the same wave equation during
observation or measurement as at all other times. This is the central
assumption of many-worlds: that the wave equation is obeyed universally
and at all times.
Everett discovered that the new, simpler theory - which he named the
"relative state" formulation - predicts that interactions between two
(or more) macrosystems typically split the joint system into a
superposition of products of relative states. The states of the
macrosystems are henceforth correlated with each other. Each element
of the superposition - each a product of subsystem states - evolves
independently of the other elements in the superposition. The states
of the macrosystems, by becoming correlated or entangled, meaning that
it no longer possible to speak the state of one system in isolation from
the other subsystems. Instead we are forced to only speak of the
relative states of the subsystems, with respect to the other subsystems.
Specifying the state of one subsystem leads to the state of the other
subsystems. In this sense the states of the subsystems are determined
only relative to each other, hence Everett's original designation of his
theory.
If one of the systems is an observer and the interaction an observation
then observer has been split into a number of copies, each copy
observing just one of the possible results of a measurement and unaware
of the other results and its own observer-copies. Interactions between
systems and their environments, including communication between
different observers in the same worlds, transmits the correlations,
inducing local splitting or decoherence of branches of the universal
wavefunction [7],[10]. Thus the entire world is split, quite rapidly,
into a host of mutually unobservable but equally real worlds.
According to many-worlds all the possible outcomes of a quantum
interaction are realised. The wavefunction, instead of collapsing at
the moment of observation, carries on evolving in a deterministic
fashion, embracing all possibilities within it. All outcomes exist
simultaneously but do not interact further with each other, each world
having split into mutually unobservable but equally real worlds or
branches of the universal wavefunction.
Q4 What is a "world"?
------------------
Loosely speaking a "world" is a complex, partially closed set of
interacting sub-systems which don't significantly interfere with other
elements in a quantum superposition. Any complex system and its coupled
environment, with a large number of internal degrees of freedom, counts
as a world. An observer, with internal irreversible processes, counts
as a complex system. In terms of the wavefunction, a world is a
decohered branch of the universal wavefunction, which represents a
single macrostate. The worlds all exist simultaneously in a non-
interacting linear superposition.
Sometimes "worlds" are called "universes", but more usually this is
reserved the totality of worlds, or "histories" (Gell-Mann/Hartle's
phrase, see "What is many-histories?").
Q5 What is a measurement?
----------------------
A measurement is an interaction between subsystems that triggers an
amplification process, typically within an object (which we often
designate as the measuring apparatus) with many internal degrees of
freedom, leading to a change in the higher-level structure of the object
(which might be the recording apparatus). The trigger is sensitive to
some (often microphysical) parameter of the one of the subsystems, which
we designate the measured system. Eg the detection of a charged
particle by a Geiger counter leads to the generation of a "click". The
absence of a charged particle does not generate a click. The measured
system is the charged particle. The interaction is with those elements
of the charged particle's wavefunction that passes *between* the charged
detector plates, triggering the amplification process (an irreversible
electron cascade or avalanche), which is ultimately converted to a
click.
A measurement, by this definition, does not require the presence of an
observer.
Q6 Why do worlds split?
---------------------
Worlds, or branches of the universal wavefunction, split when different
components of a quantum superposition "decohere" from each other [7],
[10]. Decoherence refers to the loss of coherency or absence of
interference effects between the elements of the superposition. For two
components or worlds to interfere with each other all the atoms,
subatomic particle, photons etc in each world have to be in the same
state, in the same place. For small systems this is quite possible.
In the double slit experiment, for instance, it only requires that the
divergent paths of the diffracted particle overlap again at some point,
because only the single particle has been split. For more complex
systems overlapping becomes harder because all the constituents
particles have to overlap with their counterparts simultaneously.
In QM jargon we say that the components (or vectors in the underlying
Hilbert space) have become permanently orthogonal due to the complexity
of the systems increasing the dimensionality of the Hilbert space. In
a high dimension space almost all vectors are orthogonal. Each time a
new degree of freedom is activated the dimensionality of the space which
the different components move through increases. Thus vectors for
complex systems, with a large number of degrees of freedom, naturally
decompose into mutually orthogonal components which, because they never
interfere again, are unaware of each other. From the point of view of
the complex systems they have split into different, mutually
unobservable worlds.
Q7 When do worlds split?
---------------------
Worlds irrevocably "split" at the sites of measurement-like interactions
associated with thermodynamically irreversible processes. An
irreversible process will always produce decoherence which splits
worlds. (see "Why do worlds split?", [7], [10])
In the example of a Geiger counter and a charged particle (see "What is
a measurement?") after the particle has passed the counter one world
contains the clicked counter and that portion of the particle's
wavefunction which passed though the detector. The other world contains
the unclicked counter with the particle's wavefunction with a "shadow"
cast by the counter in the particle's wavefunction. The Geiger counter
split when the amplification process became irreversible.
The splitting is local (ie originally in the region of the Geiger
counter in our example) and is transmitted causally to more distant
systems (see "Is many-worlds a local theory?" and "Does the EPR
experiment prohibit locality?"). The precise moment/location of the
split is not sharply defined due to the subjective nature of
irreversibility, but can be considered complete when much more than kT
of energy has been released in an uncontrolled fashion into the
environment. (The event has become irreversible.)
Consider Schrodinger's Cat. A cat is placed in a sealed box with a
device that releases a lethal does of cyanide if a radioactive decay is
detected. After a while an observer opens the box to see if the cat is
alive or dead. According to the CI the cat was neither alive nor dead
until the box was opened, whereupon the wavefunction of the cat
collapsed into one of the two alternatives. The paradox, according to
Schrodinger, is that the cat presumably knew if it was alive *before*
the box was opened. According to many-worlds the device was split into
two states (cyanide released or not) by the radioactive decay. As the
device/cyanide interacts with the cat the cat is split into two states
(dead or alive). From the surviving cat's point of view it occupies a
different world from its unlucky and late copy. The external observer
is split into two copies only when the box is opened and is altered by
the state of the cat.
In the language of thermodynamics the decay of the atom and the
amplification of its detection by a Geiger counter, the release of the
cyanide and the death of the cat are all irreversible events. These
events have caused the decoherence (see "Why do worlds split?") of the
different branches of the wavefunction of the cat + device + box.
Decoherence [7] occurs when irreversible macro-level events take place
and the macrostate description of an object admits no single
description. A macrostate, in brief, is the description of an object
in terms of accessible external characteristics.
The advantage of linking the definition of worlds and the splitting
process with thermodynamics is the splitting process is irreversible and
forward-time-branching, following the increase with entropy. Like all
irreversible processes, though, there are exceptions even at the coarse-
grained level and worlds will occasionally fuse. A necessary, although
not necessarily sufficient, precondition for fusing is for all records,
memories etc that discriminate between the pre-fused worlds or histories
be lost.
Q8a What is sum-over-histories?
---------------------------
The sum-over-histories or the path integral formalism was developed by
Feynman in the 1940s [F] as an alternative interpretation of quantum
mechanics, alongside Schrodinger's wave picture and Heisenberg's matrix
mechanics, for calculating transition amplitudes. All three approaches
are mathematically equivalent, but the PI formalism offers some
interesting additional insights into many-worlds.
In the PI picture the single particle wavefunction at (x',t') is built
up of contributions of all possible paths from (x,t), where each path's
contribution weighted by a (phase) factor of exp(i*Action[path]/hbar)
* wavefunction at (x,t), summed, in turn, over all values of x. The
Action[path] is the time-integral of the lagrangian (roughly: the
kinetic minus the potential energy) along the path from (x,t) to
(x',t'). The final expression is thus sum or integral over all paths,
irrespective of any classical dynamical constraints. For N-particle
systems the principle is the same, except that the paths cover a 3-N
space.
Feynman developed his PI formalism further for his work on quantum
electrodynamics, QED, with his Feynman diagrams, in parallel with
Schwinger and Tomonoga who had developed a less visualisable form of
QED. Dyson showed that these approaches were all equivalent. Feynman,
Schwinger and Tomonoga were awarded the 1965 Physics Nobel Prize for
this work.
It is quite natural, when analysing systems from the PI point of view,
to think of the particle exploring every possible intermediate
configuration between the specified start and end states. For this
reason the technique is often referred to as "sum-over-histories".
Since we do not occupy a privileged moment in history it is natural to
wonder if alternative histories are contributing equally to transition
amplitudes in the future, and therefore that each possible history has
an equal reality. Perhaps we shouldn't be surprised that Feynman,
therefore, is on record as believing in many-worlds. (See "Who believes
in many-worlds?") What is surprising is that Everett developed his
many-worlds theory entirely from the Schrodinger viewpoint without any
detectable influence from Feynman's work, despite sharing the same
thesis supervisor, John A Wheeler.
[F] Richard P Feynman _Space-time approach to non-relativistic quantum
mechanics_ Reviews of Modern Physics, Vol 20: 267-287 (1948)
Q8b What is many-histories?
-----------------------
There is considerable linkage between thermodynamics and many-worlds,
explored in the "decoherence" views of Zurek [7] and Gell-Mann and
Hartle [10], Everett [1] and others [4b].
Gell-Mann and Hartle have extended the role of decoherence in defining
the Everett worlds, or histories in their nomenclature. They call their
approach the "many-histories" approach, where each "coarse-grained or
classical history" is associated with a unique time-ordered sequence of
sets of irreversible events, including measurements, records,
observations and the like. (Fine-grained histories effectively relax
the irreversible criterion.) Physically the many-histories approach is
isomorphic to Everett's many-worlds, although Gell-Mann and Hartle
choose not to accept Everett's metaphysical stance that each history
corresponds to an element of reality.
The worlds split or "decohere" from each other when irreversible events
occur. (See "Why do worlds split?" and "When do worlds split?".)
Correspondingly many-histories defines a multiply-connected hierarchy
of classical histories where each classical history is a "child" of any
parent history which has only a subset of the child defining
irreversible events and a parent of any history which has a superset of
such events. Climbing up the tree from child to parent moves to
progressively coarser grained consistent histories until eventually the
top is reached where the history has *no* defining events (and thus
consistent with everything!). This is Everett's universal wavefunction.
The bottom of the coarse-grained tree terminates with the maximally
refined set of decohering histories. The classical histories each have
a probability assigned to them and probabilities are additive in the
sense that the sum of the probabilities associated a set classical
histories is equal to the probability associated with the unique parent
history defined by the set. (Below the maximally refined classical
histories are the fine grained or quantum histories, where probabilities
are no longer additive and different histories significantly interfere
with each other. The bottom level consists of complete microstates,
which fully specified states.)
Q9 How many worlds are there?
--------------------------
It so happens that we can use the thermodynamic Planck-Boltzmann
relationship to count the branches at each splitting, at the lowest,
maximally refined level of Gell-Mann's many-histories tree (See "What
is many-histories?"). The bottom level consists of microstates which
can be counted by the formula W = exp (S/k), where S = entropy, k =
Boltzmann's constant (approx 10^22 Joules/Kelvin) and W = number of
worlds or macrostates. The number of coarser grained worlds is lower,
but still increasing with entropy by the same ratio, ie the number of
worlds a single worlds splits into at the site of an irreversible event
is exp(dS/k), where dS = entropy of the defining event. Because k is
very small a great many worlds split off at each macroscopic event.
Q10 Is many-worlds a local theory?
------------------------------
The simplest way to see that the many-worlds metatheory is local is to
note that it requires that the wavefunction obey some relativistic wave
equation, the exact form of which is currently unknown, but which is
presumed to be locally Lorentz invariant at all times and everywhere.
This is equivalent to imposing the requirement that locality is enforced
at all times and everywhere. Ergo many-worlds is a local theory.
Another way of seeing this is examine how macrostates evolve.
Macrostates descriptions of objects evolve in a local fashion. Worlds
split as the macrostate description locally divides inside the light
cone of the triggering event. Thus the splitting is a local process,
transmitted causally at light or sub-light speeds. (See "Does the EPR
experiment prohibit locality?" for more details and "When do worlds
split?")
Q11 Is many-worlds a deterministic theory?
--------------------------------------
Yes, many-worlds is a deterministic theory, since the wavefunction obeys
a deterministic wave equation at all times. All possible outcomes of
a measurement or interaction are embedded within the universal
wavefunction although each observer, split by acts of observation, is
only aware of single outcomes due to the linearity of the wave equation.
The world appears indeterministic, with the usual probabilistic collapse
of the wavefunction, but at the objective level which includes all
outcomes determinism is restored.
Some people are under the impression that the only motivation for many-
worlds is a desire to return to a deterministic theory of physics. This
is not true. As Everett pointed out, the objection with the standard
Copenhagen interpretation is not the indeterminism per se, but that
indeterminism occurs only with the intervention of an observer, when the
wavefunction collapses.
Q12 Is many-worlds a relativistic theory?
-------------------------------------
It is trivial to relativise many-worlds because all relativistic
theories of physics are still quantum theories with linear
wavefunctions. There are three or more stages to developing a fully
quantum relativistic theory. Simplifying slightly gives:
First quantisation: the wavefunction is a complex field which evolves
in 3N dimensions which represent N particles. The wavefunction is a
solution of either the many-particle Schrodinger, Dirac or Klein-Gordon
equation or some other wave equation.
Second quantisation: AKA quantum field theory, which handles the
creation and destruction of particles by quantising fields as well as
particles. (Each particle type corresponds to a field, in QFT. Eg the
electromagnetic field's particle is the photon, but the number of
particles involved is indeterminate.) Again many-worlds has no problems
handling QFT. The wavefunction of a collection of particles and fields
exists in a Fock space, where the number of dimensions varies from
component to component.
Third quantisation. The gravitational metric is quantised, along with
(perhaps) the topology of space-time. The physics of this is
incomplete, but there is no reason for thinking that many-worlds can't
be extended to cover this as well. (One of the original motivations of
Everett's scheme was to provide a system for quantizing the
gravitational field within quantum cosmology to yield a complete
description of the universe.)
Q13 Is many-worlds (just) an interpretation?
----------------------------------------
No, for four reasons:
First, many-worlds has testable implications (see "Is many-worlds
testable?") and interpretations, generally, do not have testable
differences from each other.
Second, the mathematical structure of many-worlds is not isomorphic to
other formulations of quantum mechanics like the Copenhagen
interpretation or Bohm's hidden variables. The Copenhagen
interpretation does not contain those elements of the wavefunction that
correspond to the other worlds. Bohm's hidden variables contain
particles, in addition to the wavefunction. Therefore neither theory
is isomorphic to each other or many-worlds and are not, therefore,
merely rival "interpretations".
Third, there is no scientific, reductionistic alternative to many-
worlds. All the other theories fail for logical reasons. (See "Is
there any alternative theory?")
Four, the interpretative side of many-worlds, like the subjective
probabilistic elements, are derived from within the theory, rather than
added in by assumption, as in the conventional approach. (See "How do
probabilities emerge within many-worlds?")
Many-Worlds should really be described as a theory or, more precisely,
a metatheory, as Everett pointed out, since it makes statements that are
applicable across a range of theories. Many-worlds is the unavoidable
implication of any quantum theory which obeys some type of wave
equation, linear with respect to the wavefunction it operates on.
Q14 What are the alternatives?
--------------------------
There is no other quantum theory, besides many-worlds, that is
scientific and free of internal inconsistencies, that I am aware of.
Briefly here are the defects of the most popular alternatives:
1) Copenhagen Interpretation. Postulates that the observer obeys
different physical laws than the non-observer, which is a return
to vitalism. The definition of an observer varies from one
adherent to another, if present at all. The status of the
wavefunction is also ambiguous. If the wavefunction is real the
theory is non-local (not fatal, but unpleasant), if not real then
the theory supplies no model of reality. (See "What are the
problems with quantum theory?")
2) Hidden Variables [B]. Explicitly non-local. Bohm accepts that all
the branches of the universal wavefunction exist. Like Everett
Bohm held that the wavefunction is real complex-valued field which
never collapses. In addition he postulated that there were
particles that move under the influence of a non-local "quantum-
potential" derived from the wavefunction, in addition to the
classical potential. The action of the quantum-potential is such
that the particles are affected by only one of the branches of the
wavefunction. (Bohm derives what is essentially a decoherence
argument to show this, see section 7,#I [B]).
The implicit, unstated assumption made by Bohm is that only the
single branch of wavefunction associated with particles can contain
self-aware observers, whereas Everett makes no such assumption.
Most of Bohm's adherents do not seem to understand (or even be
aware of) Everett's criticism, section VI [1], that the hidden-
variable particles are not observable since the wavefunction alone
is sufficient to account for all observations. The particles can,
therefore, be discarded, along with the guiding quantum-potential,
yielding a theory isomorphic to many-worlds, without affecting any
experimental results.
[B] David J Bohm _A suggested interpretation of the quantum theory
in terms of "hidden variables" I and II_ Physical Review Vol
85 #2 166-193 (1952)
3) Quantum Logic. Undoubtedly the most extreme of all attempts to
solve the QM measurement problem. Apart from abandoning one or
other of the classical tenets of logic these theories are all
unfinished (presumably because of internal inconsistencies). Also
it is unclear why different types of logic apply on different
scales.
4) Extended Probability [M]. A bold theory in which the concept of
probability is "extended" to include complex values [Y]. Whilst
quite daring, I am not sure if this is logically permissable, being
in conflict with the relative frequency notion of probability, in
which case it suffers from the same criticism as quantum logic.
Also it is unclear, to me anyway, how the resultant notion of
"complex probability" differs from the "probability amplitude" and
thus why we are justified in collapsing the complex probability as
if it were a classical probability.
[M] W Muckenheim _A review of extended probabilities_ Physics
Reports Vol 133 339- (1986)
[Y] Saul Youssef _Quantum Mechanics as Complex Probability Theory_
hep-th 9307019
5) Transactional model [C]. Explicitly non-local. An imaginative
theory, based on the Feynman-Wheeler absorber-emitter model of EM,
in which advanced and retarded probability amplitudes combine into
an atemporal "transaction" to form the Born probability density.
It requires that the input and output states, as defined by an
observer, act as emitters and absorbers respectively, but not any
internal states (inside the "black box"), and, consequently,
suffers from the familiar measurement problem of the Copenhagen
interpretation.
If the internal states *did* act as emitters/absorbers then the
wavefunction would collapse, for example, around one of the double
slits (an internal state) in the double slit experiment, destroying
the observed interference fringes. In transaction terminology a
transaction forms between the first single slit and one of the
double slits and another transaction forms between the same double
slit and the point of screen where the photon lands.
[C] John G Cramer _The transactional interpretation of quantum
mechanics_ Reviews of Modern Physics Vol 58 #3 647-687 (1986)
6) many-minds. Despite its superficial similarities with many-worlds
this is actually a very unphysical, non-operational theory. (See
"What is many-minds?")
7) Non-linear theories in general. So far no non-linear theory has
any accepted experimental support, whereas many have failed
experiment. (See "Is physics linear?")
Q15 Is many-worlds testable?
------------------------
Yes, it is. There are two forms of tests: retrodictions (theory follows
data) and predictions (data follows theory).
A) A retrodiction occurs when already gathered data is accounted for by
a later theoretical advance in a more convincing fashion. The advantage
of a retrodiction over a prediction is that the data more likely to be
free of experimenter bias. An example of a retrodiction is the
perihelion shift of Mercury which Newtonian mechanics plus gravity was
unable, totally, to account for whilst Einstein's general relativity
made short work of it.
Many-worlds retrodicts all the peculiar properties of the (apparent)
wavefunction collapse in terms of decoherence. (See "Can wavefunctions
collapse?", "When do worlds split?" & "Why do worlds split?") No other
quantum theory has yet accounted for this behaviour scientifically.
(See "What are the alternatives?")
B) A prediction occurs when a theory suggests new phenomena.
Many-Worlds predicts that the Everett-worlds do not interact with each
other, because of the presumed linearity of the wave equation. However
worlds *do* interfere with each other, and this enables the theory to
be tested. (Interfere and interact mean different things in quantum
mechanics. See a guide to QM.)
According to many-worlds worlds split with the operation of every
thermodynamically irreversible process. The operation of our minds are
irreversible, carried along for the ride, and divide with the worlds.
Normally, therefore, this splitting is undetectable to us. To detect
the splitting we need to set an up experiment where a mind is split but
the world *isn't*. We need a reversible mind.
The general consensus in the literature [11], [16] is that the
experiment to detect other worlds will doable by about mid-21st century.
That date is predicted from two trendlines, both of which are widely
accepted in their own respective fields. To detect the other worlds you
need a reversible machine intelligence. This requires two things:
reversible nanotechnology and AI.
1) Reversible nanoelectronics. This is an straight-line extrapolation
based upon the log(energy) / logic operation figures, which are
projected to drop below kT in about 2020. This trend has held good for
50 years. An operation that dissipates much less than kT of energy is
reversible. (This implies that frictive or dissipative forces are
absent.) If more than kT of energy is released then, ultimately, new
degrees of freedom are activated in the environment and the change
becomes irreversible.
2) AI. Complexity of human brain = approx 10^17 bits/sec, based on the
number of neurons (approx 10^10) per human brain, average number of
synapses per neuron (approx 10^4) and the average firing rate (approx
10^3 Hz). Straight line projection of log(cost) / logic operation says
that human level, self-aware machine intelligences will be commercially
available by about 2030-2040. Uncertainty due to present human-level
complexity, but the trend has held good for 40 years.
Assuming that we have a reversible machine intelligence to hand then the
experiment consists of the machine making three measurements of the spin
of an electron (or polarisation of a photon). (1) First it measures the
spin along the z-axis. It records either spin "up" or spin "down" and
notes this in its memory. This measurements acts just to prepare the
electron in a definite state. (2) Second it measures the spin along the
x-axis and records either spin "left" or spin "right" and notes *this*
in its memory. The machine now reverses the entire x-axis measurement,
including reversibly erasing its memory of the second measurement. (3)
Third the machine takes a spin measurement along the z-axis. Again the
machine makes a note of the result.
According to the Copenhagen interpretation the original (1) and final
(3) z-axis spin measurements have only a 50% chance of agreeing because
the intervention of the x-axis measurement by the conscious observer
(the machine) caused the collapse of the electron's wavefunction.
According to many-worlds the first and third measurements will *always*
agree, because there was no intermediate wavefunction collapse. The
machine was split into two states or different worlds, by the second
measurement; one where it observed the electron with spin "left"; one
where it observed the electron with spin "right". Hence when the
machine reversed the second measurement these two worlds merged back
together, restoring the original state of the electron 100% of the time.
Q16 Could previously separate worlds diverge rather than split?
-----------------------------------------------------------
This is definitely not permissable in many-worlds. Worlds do not exist
in a quantum superposition independently of each other before they
decohere or split. The splitting is a physical process, grounded in the
dynamical evolution of the wave vector, not a matter of
philosophical/mental convenience (see "Why do worlds split?" and "When
do worlds split?") If you try to treat the worlds as pre-existing and
separate then the maths all comes out wrong. Also the divergence theory
stops being deterministic, in contradiction to the wave equations which
are deterministic, since we have a
AAAAAAAAAAAAAAABBBBBBBBBBBBBBB --------------> time
Worlds diverge
AAAAAAAAAAAAAAACCCCCCCCCCCCCCC
situation, rather than:
BBBBBBBBBBBBBBB
B
AAAAAAAAAAAAAA Worlds splitting
C
CCCCCCCCCCCCCCC
Additionally the divergence model has to explain why:
AAAAAAAAAAAAAAABBBBBBBBBBBBBBB
AAAAAAAAAAAAAAABBBBBBBBBBBBBBB
doesn't happen! This false divergence model, at the mental level, seems
favoured by adherents of many-minds. (See "What is many-minds?")
Q17 What is many-minds?
------------------
many-minds proposes, as an extra fundamental axiom, that an infinity of
separate minds or mental states be associated with each single brain
state. When the single physical brain state is split into a quantum
superposition by a measurement the associated minds are thought of as
diverging rather than splitting. The motivation for this brain-mind
dichotomy seems purely to avoid talk of minds splitting and talk instead
about the divergence of pre-existing separate mental states. There is
no physical basis for this interpretation, which is incapable of an
operational definition. Indeed the divergence model for physical
systems is specifically not permitted in many-worlds. Many-minds seems
to be proposing that minds follow different rules than matter. (See
"Could previously separate worlds diverge rather than split?")
In many-minds the role of the conscious observer is accorded special
status, with its fundamental axiom about infinities of minds, and as
such is philosophically opposed to many-worlds, which seeks to remove
the observer from any privileged role in physics. (Many-minds was co-
invented by David Albert, who has, apparently, since abandoned it. See
Scientific American July 1992 page 80 and contrast with April 94.)
The two theories should not be confused.
Q18 Does many-worlds violate Ockham's Razor?
---------------------------------------
William of Ockham, 1285-1349(?) English philosopher and one of the
founders of logic, proposed a maxim for judging theories which says that
hypotheses should not be multiplied beyond necessity. This is known as
Ockham's razor and is interpreted, today, as meaning that to account for
any set of facts the simplest theories are to be preferred over more
complex ones. Many-worlds is viewed as unnecessarily complex, by some,
by requiring the existence of a multitude of worlds to explain what we
see, at any time, in just one world.
This is to mistake what is meant by "complex". Here's an example.
Analysis of starlight reveals that starlight is very similar to faint
sunlight, with spectroscopic absorption and emission lines. Assuming
the universality of physical law we are led to conclude that other stars
and worlds are scattered, in great numbers, across the cosmos. The
theory that "the stars are distant suns" is the simplest theory and so
to be preferred by Ockham's Razor to other geocentric theories.
Similarly many-worlds is the simplest and most economical theory because
it proposes that same laws of physics apply to animate observers as
inanimate objects. The multitude of worlds predicted by the theory is
not a weakness for many-worlds, any more than stars are for astronomy,
since the non-interacting worlds emerge from a simpler theory.
(As an historical aside it is worth noting that Ockham's razor was also
falsely used to argue in favour of the older heliocentric theories
*against* Galileo's notion of the vastness of the cosmos. The notion
of vast empty interstellar spaces was too uneconomical to be believable.
Again they were confusing the notion of vastness with complexity [15].)
Q19 Does the multiplication of worlds violate conservation of energy?
-----------------------------------------------------------------
First, the law conservation of energy is based on observations within
each world. All observations within each world are consistent with
conservation of energy, therefore energy is conserved.
Second, and more precisely, conservation of energy, in QM, is formulated
in terms weighted averages or of expectation values. Conservation of
energy is expressed by saying that the time derivative of the
expectation of the energy operator vanishes. This statement can be
scaled up to include the whole universe. Each world has an approximate
energy, but the energy of (any subset of) the total wavefunction
involves summing over each world, weighted with its probability measure.
This weighted sum is a constant. So energy is conserved within each
world and across the totality of worlds.
One way of viewing this result - that observed conserved quantities are
conserved across the totality of worlds - is to note that new worlds are
not created by the action of the wave equation, rather existing worlds
are split into successively "thinner" and "thinner" slices, as measured
in the Hilbert space.
Q20 How do probabilities emerge within many-worlds?
-----------------------------------------------
Everett demonstrated [1],[2] that observations in each world obey all
conventional statistical laws predicted by the probabilistic Born
interpretation by showing that the Hilbert space's inner product or norm
supplies a unique measure or "volume" to each world or set of worlds.
The norm of the set of worlds where experiments contradict the Born
interpretation (non-random or maverick worlds) vanishes in the limit as
the number of probabilistic trials goes to the limit. Vectors with zero
norm, where probability breaks down, don't exist (see below), thus we,
as observers, observe the familiar predictions of quantum theory
expressed as probabilistic events.
Strictly speaking Everett did not prove that the usual statistical laws
of the Born interpretation would hold true for all observers in all
worlds. He merely showed that no other statistical laws would hold true
and asserted the vanishing of the Hilbert space volume of the set of
non-random worlds. DeWitt (with Graham) later published a longer
*derivation* of Everett's assertion [4a],[4b]. What Everett asserted
and DeWitt derived is that the collective norm of all the maverick
worlds, as the number of trials goes to infinity, vanishes. Since the
only vector in a Hilbert space with vanishing norm is the null vector
(a defining axiom of a Hilbert space) this is equivalent to saying that
non-randomness is never realised. Thus all worlds obey the usual Born
predictions of quantum theory.
Of course we have to assume that the wavefunction is a Hilbert space
vector in the first place but since this assumption is also made in the
standard formulation this is not a weakness of many-worlds since we are
not trying to justify all the axioms in the conventional formulation of
QM, merely those that relate to probabilities and collapse.
In more detail the steps are:
1) Construct the tensor product of N identical systems in state |psi>,
according to the usual rules for Hilbert space composition
(repeated indices summed):
|PSI_N> = |psi_1>*|psi_2>*...... |psi_N> where
|psi_j> = jth system prepared in state |psi>
= |i_j><i_j|psi> (ie the amplitude of the ith eigenstate
is independent of which system it is in)
so that
|PSI_N> = |i_1>|i_2>...|i_N><i_1|psi><i_2|psi>...<i_N|psi>
2) Quantify the deviation from the "expected" Born-mean for each
component of |PSI_N> with respect to the above |i_1>|i_2>...|i_N>
basis by counting the number of occurrences of the ith
eigenstate/N. Call this number RF(i). Define the Born-deviation
as D = sum(i)( (RF(i) - |<i|psi>|^2)^2 ). Thus D, loosely
speaking, for each N length sequence expresses how "non-random" a
particular sequence is although, of course, no finite sequence is
excluded from happening since the concept of non-random becomes
precise only as N goes to infinity [H].
3) Sort out terms in the expansion of |PSI_N> according to whether D
is less/equal to (.LE.) or greater than (.GT.) E, where E is a
real, positive constant. Collecting terms together we get:
|PSI_N> = |N,"D.GT.E"> + |N,"D.LE.E">
worlds worlds
for which for which
D > E D <= E
4) What DeWitt showed was that:
<N,"D.GT.E"|N,"D.GT.E"> < 1/(NE) (proof in appendix of 4b)
Thus as N goes to infinity then the right-hand side vanishes for
all positive values of E. (This mirrors the classical
"frequentist" position on probability which states that if i occurs
with probability p(i) then the proportion of N trials with success
i approaches p(i)/N as N goes to infinity [H]. This has the
immediate benefit that sum(i) = 1.) The norm of |N,"D.LE.E">, by
contrast, approaches 1 as N goes to infinity.
5) The norm of the collection of non-random worlds vanishes and
therefore must be identified with the some complex multiple of the
null vector.
6) Since (by assumption) the state vector faithfully models reality
then the null vector cannot represent any element of reality since
it can be added to (or subtracted from) any other state vector
without altering the other state vector.
7) Ergo the non-random worlds are not realised, without making any
additional physical assumptions.
The emergence of Born-style probabilities as a consequence of the
mathematical formalism of the theory, without any extra interpretative
assumptions, is another reason why the Everett metatheory should not be
regarded as just an interpretation. (See "Is many-worlds (just) an
interpretation?") The interpretative elements are forced by the
mathematical structure of the axioms.
[H] JB Hartle _Quantum Mechanics of Individual Systems_ American
Journal of Physics Vol 36 #8 704-712 (1968) Hartle has
investigated the N goes to infinity limit in more detail and more
generally. He shows that the relative frequency operator obeys
RF(i) |psi_1>|psi_2>.... = |<i|psi>|^2 |psi_1>|psi_2>....
Q21 Does many-worlds allow free-will?
---------------------------------
Many-Worlds, whilst deterministic on the objective universal level, is
indeterministic on the subjective level so the situation is certainly
no better or worse for free-will than in the Copenhagen view.
Traditional Copenhagen indeterministic quantum mechanics only slightly
weakens the case for free-will. In quantum terms each neuron is an
essentially classical object. Consequently quantum noise in the brain
is at such a low level that it probably doesn't often alter, except very
rarely, the critical mechanistic behaviour of sufficient neurons to
cause a decision to be different than we might otherwise expect. The
consensus view amongst experts is that free-will is the consequence of
the mechanistic operation of our brains, the firing of neurons,
discharging of synapses etc and fully compatible with the determinism
of classical physics. Free-will is the inability of a mechanism to
predict its own future actions due to the logical impossibility of any
mechanism containing a complete model of itself rather than any inherent
indeterminism in the mechanism's operation.
Nevertheless, some people find that with all possible decisions being
realised in different worlds that the prima facia situation for free-
will looks quite difficult. Does this multiplicity of outcomes destroy
free-will? If both sides of a choice are selected in different worlds
why bother to spend time weighing the evidence before selecting? The
answer is that whilst all decisions are realised, some are realised more
often than others - or to put to more precisely each branch has its own
weighting or measure which enforces the usual laws of quantum
statistics.
The measure is supplied by the mathematical structure of Hilbert spaces.
Every Hilbert space has a norm, constructed from the inner product, -
which we can think of as analogous to a volume - which weights each
world or collection of worlds. A world of zero volume is never
realised. Worlds in which the conventional statistical predictions
consistently break down have zero volume and so are never realised.
(See "How do probabilities emerge within many-worlds?")
Thus our actions, as expressions of our will, correlate with the weights
associated with worlds. This, of course, matches our subjective
experience of being able to exercise our will, form moral judgements and
be held responsible for our actions.
Q22 Why am I in this world and not another?
---------------------------------------
or
Why the universe appears random, but isn't.
-------------------------------------------
Consider, for a moment, this analogy:
Suppose Fred has his brain divided in two and transplanted into
different cloned bodies (this is a gedanken operation!). Let's further
suppose that each half brain is regenerates to full functionality and
we name the resultant individuals Fred-left and Fred-right. Fred-left
can ask, why did I end up as Fred-left? Similarly Fred-right can ask,
why did I end up as Fred-right? The only answer possible is that there
was *no* reason. From Fred's point of view it is a subjectively
*random* choice which individual Fred ends up as. To the surgeon the
whole process is deterministic. To Fred it seems random.
Same with many-worlds. There was no reason "why" you ended up in this
world, rather than another. It was a subjectively random choice, an
artifact of your consciousness being split. The universe is, in effect,
performing umpteen split-brain operations on us all the time. The
randomness apparent in nature is a consequence of the splitting of
worlds.
(See "How do probabilities emerge within many-worlds?" for how the
subjective randomness is moderated by the usual probabilistic laws of
QM.)
Q23 Can wavefunctions collapse?
---------------------------
Many-Worlds predicts/retrodicts that wavefunctions appear to collapse
(see "The EPR experiment"), when measurement-like interactions and
processes occur via a process called decoherence [7], [10], but claims
that they do not *actually* collapse but continue to evolve according
to the usual wave-equation. If a *mechanism* for collapse could be
found then there would be no need for many-worlds. The reason why we
doubt that collapse takes place is because no one has ever been able to
devise a physical mechanism that could trigger it.
The Copenhagen interpretation posits that observers collapse
wavefunctions, but is unable to define "observer". (See "What is the
Copenhagen interpretation?" and "Is there any alternative theory?")
Without a definition there can be no mechanism.
Another popular view is that irreversible processes trigger collapse.
Certainly wavefunctions *appear* to collapse whenever irreversible
processes are involved in measurement or amplification and most
macroscopic, day-to-day events are irreversible. The problem is, as
with positing observers as a cause of collapse, that any irreversible
process is composed of a large number of sub-processes that are each
individually reversible. To invoke irreversibility as a *mechanism* for
collapse we would have to show that new *fundamental* physics comes into
play for complex systems, which is quite absent at the atom/molecular
level. Atoms and molecules are empirically observed to obey some type
of wave equation. We have no evidence for an extra mechanism operating
on more complex systems. As far as we can determine complex systems are
described by the same quantum-operation of their simpler components.
(Note: chaos, complexity theory, etc, do not introduce new fundamental
physics. They still operate within the reductionistic paradigm -
despite what many popularisers say.)
Other people have attempted to construct non-linear theories so that
microscopic systems are approximately linear and obey the wave equation
but macroscopic systems are grossly non-linear and generates collapse.
Unfortunately all these efforts have made additional predictions which,
when tested, have failed.
(Another reason for doubting that any collapse actually takes place is
that the collapse would have to propagate instantaneously or in some
space-like fashion, otherwise the same particle would be observed more
than one at different locations. Not fatal, but unpleasant and
difficult to reconcile with relativity.)
The simplest conclusion is that wavefunctions just *don't* collapse and
that all branches of the wavefunction exist.
Q24 Is physics linear?
------------------
or
Could we ever communicate with the other worlds?
------------------------------------------------
or
Why do I only ever experience one world?
----------------------------------------
According to our present knowledge of physics whilst it is possible to
detect the presence of other nearby worlds, through the existence of
interference effects, it is impossible travel to or communicate with
them. Mathematically this corresponds to an empirically verified
property of all quantum theories called linearity which says that the
worlds can interfere with each other with respect to a external,
unsplit, observer or system (whence they are manifest as diffraction or
interference patterns) but they can't influence each other in the sense
that an experimenter can arrange to communicate with their own, already
split-off, quantum copies.
Specifically the wave equation is linear, with respect to the
wavefunction or state vector, which means that given any two solutions
of the wavefunction with identical boundary conditions then any linear
combination of the solutions is also a solution itself. Since each
component of a linear solution evolves with complete indifference as to
the presence or absence of the other terms then we can conclude that no
experiment in one world can have any effect on another experiment in
another world. Hence no communication is possible between quantum
worlds.
Linearity (of the wavefunction) has been verified hold true to better
than 1 part in 10^27 [W] and some scientists believe that it is
absolutely true for various theoretical reasons. If slight non-linear
effects were ever discovered then the possibility of communication
with/travel to the other worlds would be opened up.
[W] Steven Weinberg __ Annals of Physics Vol 194 #2 336-386 (1989) and
_Dreams of a Final Theory_ (1992)
Q25 Can we determine what other worlds there are?
---------------------------------------------
or
Is the form of the Universal Wavefunction knowable?
---------------------------------------------------
To calculate the form of the universal wavefunction requires not only
a knowledge of its dynamics (which we have a good approximation to, at
the moment) but also of the boundary conditions. To actually calculate
the form of the universal wavefunction, and hence make inferences about
*all* the embedded worlds, we would need to know the boundary conditions
as well. We are presently restricted to making inferences about those
worlds with which have shared a common history up to some point, which
have left traces (records, fossils, etc) still discernable today. This
restricts us to a subset of the extant worlds which have shared the same
boundary conditions with us. The further we probe back in time the less
we know of the boundary conditions and therefore the less we can know
of the universal wavefunction.
This limits us to drawing conclusions about a restricted subset of the
worlds - all the worlds which are consistent with our known history up
to a some common moment, before they diverging. The flow of historical
events is, according to chaos/complexity theory/thermodynamics, very
sensitive to amplification of quantum-scale uncertainty and this
sensitivity is a future-directed one-way process. We can make very
reliable deductions about the past from the knowledge future/present but
we can't predict the future from knowledge the past/present.
Thermodynamics implies that the future is harder to predict than the
past is to retrodict. Books get written about this "arrow of time"
problem but we'll just have to accept this as given. The fossil and
historical records say that dinosaurs and Adolf Hitler once existed but
have little to say about future.
Consider the effects of that most quantum of activities, Brownian
motion, on the conception of individuals and the knock-on effects on the
course of history. Mutation itself, one of the sources of evolutionary
diversity, is a quantum event. For an example of the
biological/evolutionary implications see Stephen Jay Gould's book
"Wonderful Life" for an exploration of the thesis that the path of
evolution is driven by chance. According to Gould evolutionary history
forms an enormously diverse tree of possible histories - all very
improbable - with our path being selected by chance. According to many-
worlds all these other possibilities are realised. Thus there are
worlds in which Hitler won WW-II and worlds in which the dinosaurs never
died out. We can be as certain of this as we are that Hitler and the
dinosaurs once existed in our own past.
Whether or not we can ever determine the totality of the universal
wavefunction is an open question. If Steven Hawking's work on the no-
boundary-condition condition is ultimately successful, or it emerges
from some theory of everything, and many think it will, then the actual
form of the *total* wavefunction could, in principle, we determined from
a complete knowledge physical law itself.
Q26 Who was Everett?
----------------
Hugh Everett III (1930-1982) did his undergraduate study in chemical
engineering at the Catholic University of America. Studying von
Neumann's and Bohm's textbooks as part of his graduate studies, under
Wheeler, in mathematical physics at Princeton University in the 1950s
he became dissatisfied (like many others) with the collapse of the
wavefunction. He developed, during discussions with Charles Misner and
Aage Peterson (Bohr' assistant, then visiting Princeton), his "relative
state" formulation. Wheeler encouraged his work and preprints were
circulated in January 1956 to a number of physicists. A condensed
version of his thesis was published as a paper to "The Role of Gravity
in Physics" conference held at the University of N Carolina, Chapel
Hill, N Carolina in January 1957.
Everett was discouraged by the lack of response from others,
particularly Bohr, whom he flew to Copenhagen to meet but got the
complete brush-off from. Leaving physics after completing his Ph.D,
Everett worked as a defense analyst at the Weapons Systems Evaluation
Group, Pentagon. At some point he became a private contractor,
apparently quite successfully for he became a multimillionaire. In 1968
Everett worked for the Lambda Corp. His published papers during this
period cover things like optimising resource allocation and, in
particular, maximising enemy kill rates during nuclear-weapon campaigns.
Later (from 1968 onwards) Bryce S DeWitt, one of the 1957 Chapel Hill
conference organisers, but better known as one of the founders of
quantum gravity, successfully popularised Everett's relative state
formulation as the "many-worlds interpretation" in a series of articles
[4a],[4b],[5].
Sometime in 1976-9 Everett visited Austin, Texas, at Wheeler or DeWitt's
invitation, to give some talks on QM. The strict no-smoking rule in the
auditorium was relaxed for Everett (a chain smoker); the only exception
ever. Everett, apparently, had a very intense and agitated manner, and
spoke with a very acute style, correctly anticipating and cutting off
questions after a few words. Oh yes, a bit of trivia, he drove a
Cadillac with horns.
With the steady growth of interest in many-worlds in the late 1970s
Everett planned returning to physics to do more work on the subject of
measurement in quantum theory, but died of a heart attack in 1982.
Survived by his wife.
Q27 Who believes in many-worlds?
----------------------------
"Political scientist" L David Raub reports a poll of 72 of the "leading
cosmologists and other quantum field theorists" about the "Many-Worlds
Interpretation" and gives the following breakdown [T].
1) "Yes, I think MWI is true" 58%
2) "No, I don't accept MWI" 18%
3) "Maybe it's true but I'm not yet convinced" 13%
4) "I have no opinion one way or the other" 11%
Amongst the "Yes, I think MWI is true" crowd listed are Stephen Hawking
and Nobel Laureates Murray Gell-Mann and Richard Feynman. Gell-Mann and
Hawking recorded reservations with the name "many-worlds", but not with
the content. Nobel Laureate Steven Weinberg is also mentioned as a
many-worlder, although the suggestion is, not when the poll was
conducted, presumably before 1988 (when Feynman died). The only "No,
I don't accept MWI" listed by name is Penrose.
[T] FJ Tipler _The Physics of Immortality_, pages 170-1
Q28 Does the EPR experiment prohibit locality?
------------------------------------------
The EPR experiment is widely regarded as the definitive gedanken
experiment for demonstrating that quantum mechanics is non-local or
incomplete. We shall see that it implies neither.
The EPR experiment was devised, in 1935, by Einstein, Podolsky and Rosen
to demonstrate that quantum mechanics was incomplete [E]. Bell, in
1964, demonstrated that any hidden variables theory, to replicate the
predictions of QM, must be non-local [B]. QM predicts strong
correlations between separated systems, stronger than any local hidden
variables theory can offer. Bell encoded this statistical prediction
in the form of some famous inequalities that apply to any type of EPR
experiment. Eberhard, in the late 1970s, extended Bell's inequalities
to cover any local theory, with or without hidden variables. Thus the
EPR experiment plays a central role in sorting and testing variants of
QM. All the experiments attempting to test EPR/Bell's inequality to
date (including Aspect's in the 1980s [As]) are in line with the
predictions of standard QM - hidden variables are ruled out. Here is
the paradox of the EPR experiment. It seems to imply that any physical
theory must involve faster-than-light "things" going on to maintain
these "spooky" action-at-a-distance correlations and yet still be
compatible with relativity, which seems to forbid FTL.
Let's examine the EPR experiment in more detail.
So what did EPR propose? The original proposal was formulated in terms
of correlations between the positions and momenta of two once-coupled
particles. Here I shall describe it in terms of the spin (a type of
angular momentum intrinsic to the particle) of two electrons. [In this
treatment I shall ignore the fact that electrons always form
antisymmetric combinations. This does not alter the results but does
simplify the maths.] Two initially coupled electrons, with opposed
spins that sum to zero, move apart from each other across a distance of
perhaps many light years, before being separately detected, say, by me
on Earth and you on Alpha Centauri with our respective measuring
apparatuses. The EPR paradox results from noting that if we choose the
same (parallel) spin axes to measure along then we will observe the two
electrons' spins to be anti-parallel (ie when we communicate we find
that the spin on our electrons are correlated and opposed). However if
we choose measurement spin axes that are perpendicular to each other
then there is no correlation between electron spins. Last minute
alterations in a detector's alignment can create or destroy correlations
across great distances. This implies, according to some theorists, that
faster-than-light influences maintain correlations between separated
systems in some circumstances and not others.
Now let's see how many-worlds escapes from this dilemma.
The initial state of the wavefunction of you, me and the electrons and
the rest of the universe may be written:
|psi> = |me> |electrons> |you> |rest of universe>
on in on
Earth deep Alpha
space Centauri
or more compactly, ignoring the rest of the universe, as:
|psi> = |me,electrons,you>
And
|electrons> = (|+,-> - |-,+>)/sqrt(2)
represents a pair electrons, with the first electron travelling
towards Earth and the second electron travelling towards Alpha
Centauri.
|+> represents an electron with spin in the +z direction
|-> represents an electron with spin in the -z direction
It is an empirically established fact, which we just have to accept,
that we can relate spin states in one direction to spin states in other
directions like so (where "i" is the sqrt(-1)):
|left> = (|+> - |->)/sqrt(2) (electron with spin in -x direction)
|right> = (|+> + |->)/sqrt(2) (electron with spin in +x direction)
|up> = (|+> + |->i)/sqrt(2) (electron with spin in +y direction)
|down> = (|+> - |->i)/sqrt(2) (electron with spin in -y direction)
and inverting:
|+> = (|right> + |left>)/sqrt(2) = (|up> + |down>)/sqrt(2)
|-> = (|right> - |left>)/sqrt(2) = (|down> - |up>)i/sqrt(2)
(In fancy jargon we say that the spin operator in different directions
form non-commuting observables. I shall eschew such obfuscations.)
Working through the algebra we find that for pairs of electrons:
|+,-> - |-,+> = |left,right> - |right,left>
= |up,down>i - |down,up>i
|me> represents me on Earth with my detection apparatus. I shall assume
that we are capable of either measuring spin in the x or y direction,
which are both perpendicular the line of flight of the electrons. After
having measured the state of the electron my state is described as one
of either:
|me[l]> represents me + apparatus + records having measured
x-axis spin and recorded the x-axis spin as "left"
|me[r]> ditto with the x-axis spin as "right"
|me[u]> ditto with the y-axis spin as "up"
|me[d]> ditto with the y-axis spin as "down"
Similarly for |you> on Alpha Centauri. Notice that it is irrelevant
*how* we have measured the electron's spin. The details of the
measurement process are irrelevant. To model the process it is
sufficient to assume that there is a way, which we have further assumed
does not disturb the electron. (The latter assumption may be relaxed
without altering the results.)
To establish familiarity with the notation let's take the state of the
initial wavefunction as:
|psi>_1 = |me,left,up,you>
/ \
/ \
first electron in left second electron in up state
state heading towards heading towards you on
me on Earth Alpha Centauri
After the electrons arrive at their detectors, I measure the spin
along the x-axis and you along the y-axis. The wavefunction evolves
into |psi>_2:
local
|psi>_1 ============> |psi>_2 = |me[l],left,up,you[u]>
observation
which represents me having recorded my electron on Earth with spin left
and you having recorded your electron on Alpha Centauri with spin up.
The index in []s indicates the value of the record. This may be held
in the observer's memory, notebooks or elsewhere in the local
environment (not necessarily in a readable form). If we communicate our
readings to each other the wavefunctions evolves into |psi>_3:
remote
|psi>_2 ============> |psi>_3 = |me[l,u],left,up,you[u,l]>
communication
where the second index in []s represents the remote reading entering the
observers' local records. Notice that the results both agree with each
other. Eg my record of your reading agrees with your reading.
That's the notation established. Now let's see what happens in the more
general case where, again,:
|electrons> = (|+,-> - |-,+>)/sqrt(2).
First we'll consider the case where you and I have previously arranged
to measure the our respective electron spins along the same x-axis.
Initially the wavefunction of the system of electrons and two
experimenters is:
|psi>_1 =
|me,electrons,you>
= |me>(|left,right> - |right,left>)|you> /sqrt(2)
= |me,left,right,you> /sqrt(2)
- |me,right,left,you> /sqrt(2)
After the we each perform our measurements we get:
|psi>_2
= |me[l],left,right,you[r]> /sqrt(2)
- |me[r],right,left,you[l]> /sqrt(2)
The observers (you and me) have been split (on Earth and Alpha Centauri)
into relative states (or local worlds) which correlate with the state
of the electron. If we now communicate over interstellar modem (this
will take a few years since you and I are separated by light years, but
no matter) then, for example, the world corresponding to the 2nd term
in the above expansion contains me having seen my electron with spin
right also contains you having seen your electron with spin left. So
we jointly agree, in both worlds, that spin has been conserved.
Now suppose that we had prearranged to measure the spins along different
axes. Suppose I measure the x-direction spin and you the y-direction
spin. Now things get a bit more complex. To analyse what happens we
need to decompose the two electrons along their respective spin axes.
|psi>_1 =
|me,electrons,you>
= |me>(|+,-> - |-,+>)|you>/sqrt(2)
= |me> (
(|right>+|left>)i(|down>-|up>)
- (|right>-|left>)(|down>+|up>)
) |you> /2*sqrt(2)
= |me> (
|right>(|down>-|up>)i
+ |left> (|down>-|up>)i
- |right>(|down>+|up>)
+ |left> (|down>+|up>)
) |you> /2*sqrt(2)
= |me> (
|right,down> (i-1) - |right,up> (1+i)
+ |left,up> (1-i) + |left,down> (1+i)
) |you> /2*sqrt(2)
= (
+ |me,right,down,you> (i-1)
- |me,right,up,you> (i+1)
+ |me,left,up,you> (1-i)
+ |me,left,down,you> (1+i)
) /2*sqrt(2)
So after you and I make our local observations we get:
|psi>_2 =
(
+ |me[r],right,down,you[d]> (i-1)
- |me[r],right,up,you[u]> (i+1)
+ |me[l],left,up,you[u]> (1-i)
+ |me[l],left,down,you[d]> (1+i)
) /2*sqrt(2)
Each term realises a possible outcome of the joint measurements. The
interesting thing is that whilst we can decompose it into four terms
there are only two states for each observer. Looking at myself, for
instance, we can rewrite this in terms of states relative to *my*
records/memories.
|psi>_2 =
(
|me[r],right> ( |down,you[d]> (i-1) - |up,you[u]> (i+1) )
+ |me[l],left> ( |up,you[u]> (1-i) + |down,you[d]> (1+i) )
) /2*sqrt(2)
And we see that there are only two copies of *me*. Equally we can
rewrite the expression in terms of states relative to *your*
records/memory.
|psi>_2 =
(
( |me[l],left> (1-i) - |me[r],right> (i+1) ) |up,you[u]>
+ ( |me[r],right> (i-1) + |me[l],left> (1+i) ) |down,you[d]>
) /2*sqrt(2)
And see that there are only two copies of *you*. We have each been
split into two copies, each perceiving a different outcome for our
electron's spin, but we have not been split by the measurement of the
remote electron.
*After* you and I communicate our readings to each other, > four years
later, we get:
|psi>_3 =
(
+ |me[r,d],right,down,you[d,r]> (i-1)
- |me[r,u],right,up,you[u,r]> (i+1)
+ |me[l,u],left,up,you[u,l]> (1-i)
+ |me[l,d],left,down,you[d,l]> (1+i)
) /2*sqrt(2)
The decomposition into four worlds is only forced and unique after
communication between the remote systems. Until the two observers
communicated their results to each other they were each unsplit by each
others' remote measurements, although their own local measurements had
split themselves. The splitting is a local process that is causally
transmitted from system to system at light or sub-light speeds. (This
is a point that Everett stressed about Einstein's remark about the
observations of a mouse, in the Copenhagen interpretation, collapsing
the wavefunction of the universe. Everett observed that it is the mouse
that's split by its observation of the rest of the universe. The rest
of the universe is unaffected and unsplit.)
When all communication is complete the worlds have finally decomposed
or decohered from each other. Each world contains a consistent set of
observers, records and electrons, in perfect agreement with the
predictions of standard QM. Further observations of the electrons will
agree with the earlier ones and so each observer, in each world, can
henceforth regard the electron's wavefunction as having collapsed to
match the historically recorded, locally observed values. This
justifies our operational adoption of the collapse of the wavefunction
upon measurement, without having to strain our credibility by believing
that it actually happens.
To recap. Many-worlds is local and deterministic. Local measurements
split local systems (including observers) in a subjectively random
fashion; distant systems are only split when the causally transmitted
effects of the local interactions reach them. We have not assumed any
non-local FTL effects, yet we have reproduced the standard predictions
of QM.
So where did Bell and Eberhard go wrong? They thought that all theories
that reproduced the standard predictions must be non-local. It has been
pointed out by both Albert [A] and Cramer [C] (who both support
different interpretations of QM) that Bell and Eberhard had implicity
assumed that every possible measurement - even if not performed - would
have yielded a *single* definite result. This assumption is called
contra-factual definiteness or CFD [S]. What Bell and Eberhard really
proved was that every quantum theory must either violate locality *or*
CFD. Many-worlds with its multiplicity of results in different worlds
violates CFD, of course, and thus can be local.
Thus many-worlds is the only local quantum theory in accord with the
standard predictions of QM and, so far, with experiment.
[A] David Z Albert, _Bohm's Alternative to Quantum Mechanics_
Scientific American (May 1994)
[As] Alain Aspect, J Dalibard, G Roger _Experimental test of Bell's
inequalities using time-varying analyzers_ Physical Review Letters
Vol 49 #25 1804 (1982).
[C] John G Cramer _The transactional interpretation of quantum
mechanics_ Reviews of Modern Physics Vol 58 #3 647-687 (1986)
[B] John S Bell: _On the Einstein Podolsky Rosen paradox_ Physics 1
#3 195-200 (1964).
[E] Albert Einstein, Boris Podolsky, Nathan Rosen: _Can
quantum-mechanical description of physical reality be considered
complete?_ Physical Review Vol 41, 777-780 (15 May 1935).
[S] Henry P Stapp _S-matrix interpretation of quantum-theory_ Physical
Review D Vol 3 #6 1303 (1971)
31 References and further reading
------------------------------
[1] Hugh Everett III _The Theory of the Universal Wavefunction,
Princeton thesis_ (1956?)
The original and most comprehensive paper on many-worlds.
Investigates and recasts the foundations of quantum theory in
information theoretic terms, before moving on to consider the
nature of interactions, observation, entropy, irreversible
processes, classical objects etc. 138 pages. Only published in
[5].
[2] Hugh Everett III _"Relative State" Formulation of Quantum
Mechanics_ Reviews of Modern Physics Vol 29 #3 454-462, (July
1957) A condensation of [1] focusing on observation.
[3] John A Wheeler _Assessment of Everett's "Relative State"
Formulation of Quantum Theory_, Reviews of Modern Physics Vol
29 #3 463-465 (July 1957) Wheeler was Everett's PhD
supervisor.
[4a] Bryce S DeWitt _Quantum Mechanics and Reality_ Physics Today,
Vol 23 #9 30-40 (September 1970) One of the earlier, and more
accurate, popularisations of Everett's work. The April 1971
issue has reader feedback and DeWitt's responses.
[4b] Bryce S DeWitt _The Many-Universes Interpretation of Quantum
Mechanics_ in _Proceedings of the International School of Physics
"Enrico Fermi" Course IL: Foundations of Quantum Mechanics_
Academic Press (1972)
[5] Bryce S DeWitt, R Neill Graham eds _The many-worlds
Interpretation of Quantum Mechanics_, Contains
[1],[2],[3],[4a],[4b] plus other material. Princeton Series
in Physics, Princeton University Press (1973) ISBN 0-691-
08126-3 (hard cover), 0-691-88131-X (paper back) The
definitive guide to many-worlds, if you can get hold of a
copy, but now (1994) only available xeroxed from microfilm
(ISBN 0-7837-1942-6) from Books On Demand, 300 N Zeeb Road,
Ann Arbor, MI 48106-1346, USA. Tel: +01-313 761 4700 or 800
521 0600.
[15] Frank J Tipler _The many-worlds interpretation of quantum mechanics
in quantum cosmology_ in _Quantum Concepts of Space and Time_ eds
Roger Penrose and Chris Isham, Oxford University Press (1986). Has
a discussion of Ockham's razor.
On quantum theory, measurement and decoherence generally:
[6] John A Wheeler, Wojciech H Zurek eds _Quantum Theory and
Measurement_ Princeton Series in Physics, Princeton University
Press (1983) ISBN 0-691-08316-9. Contains 49 classic
articles, including [2], covering the history and development
of interpretations of quantum theory.
[7] Wojciech H Zurek _Decoherence and the Transition from the
Quantum to the Classical_, Physics Today, 36-44 (October
1991). The role of thermodynamics and the properties of large
ergodic systems (like the environment) are related to the
decoherence or loss of interference effects between superposed
macrostates.
[8] Max Jammer _The Philosophy of Quantum Mechanics_ Wiley, New
York (1974) Almost every interpretation of quantum mechanics
is covered and contrasted. Section 11.6 contains a lucid
review of many-worlds theories.
[9] Marian O Scully, Bethold-Georg Englert, Herbert Walther _Quantum
optical tests of complementarity_ Nature, Vol 351, 111-116 (9 May
1991). Demonstrates that quantum interference effects are destroyed
by irreversible object-apparatus correlations, not by the
measurement process itself.
[10] Murray Gell-Mann, James B Hartle _Quantum Mechanics in the Light
of Quantum Cosmology_ Proceedings of the 3rd International
Symposium on the Foundations of Quantum Mechanics (1989) 321-343.
They accept the Everett's decoherence analysis, and have extended
it further, but reject many-worlds' metaphysical stance.
Tests of the Everett metatheory:
[11] David Deutsch _Quantum theory as a universal physical theory_
International Journal of Theoretical Physics, Vol 24 #1
(1985). Describes an experiment which tests for the existence
of superpositions of *consciousness (in an AI).
[16] David Deutsch _Three connections between Everett's interpretation
and experiment_ Quantum Concepts of Space and Time, eds Roger
Penrose and Chris Isham, Oxford University Press (1986). Discusses
a testable split observer experiment and quantum computing.
On quantum computers:
[12] David Deutsch _Quantum theory, the Church-Turing principle and the
universal quantum computer_ Proceedings of the Royal Society of
London, Vol. A400, 96-117 (1985).
[13] David Deutsch _Quantum computational networks_ Proceedings of
the Royal Society of London, Vol. A425, 73-90 (1989).
[14] David Deutsch and R. Jozsa _Rapid solution of problems by
quantum computation_ Proceedings of the Royal Society of
London, Vol. A439, 553-558 (1992).
*******************
Mike Price pr...@price.demon.co.uk
Peter Norton
My many worlds split with ecstasy at seeing THE one true FAQ with my own many
eyes. I am not worthy! I am not worthy!
What good fortune to be born in these many worlds and what good fortune to
have seen the true FAQ!
many thanks.
Well done!
----
"Bohm + Ockham => Everett" (chain smoking and driving a cadillac with horns?)
-Mike Price
Andy Boden
I too enjoyed the many-worlds FAQ, even though I'm not a convert to
the "one true faith". In it Mike (or whomever) makes some fantastic
claims that may or may not be true depending on how litteraly one
takes their axiomatic theories, but that's okay. On that count I
certainly disagree that Mike is a crackpot, he's just too zealous to
be objective (my spin).
However, the above comment, which is indicative of the dogmatic
viewpoints that supporters of the Everett "meta-theory" invariably
seem to hold, is EXACTLY why the non-converts look at the Everett
"movement" with such distain. Silly retrodictive arguments aside,
until *unique* *predictive* tests demonstrate the reality of the
Everett wavefunction, it remains in the arena of well-motivated
spectulation (at least in a scientific context).
- A.B.
--
Jack Sarfatti
>"movement" with such distain. Silly retrodictive arguments aside,
>until *unique* *predictive* tests demonstrate the reality of the
>Everett wavefunction, it remains in the arena of well-motivated
>spectulation (at least in a scientific context).
>
> - A.B.
"Silly retrodictive arguments"? - your retarded causality prejudice is
showing! :-) I get my best ideas from the future. Everytime I hear
the word "unitarity" I pull out my collapsor.
>
>"...it doesn't matter how beautiful your theory is, it doesn't matter
>how smart you are -- if it doesn't agree with experiment, it's wrong."
>
> - R.P. Feynman
>
Agreed - provided the experiment is done correctly and replicated. I suspect
that all of the experiments that test for causal dispersion relations are
flawed with ad-hoc parameters that make them fit sort of like Ptolemaic
"epicycles". All the classic experiments testing for causality should be redone.
This would also generate new funding for high energy physics now that the SSC
is dead. We could make a case that it would test Tipler's thesis and thereby
get the influential religious right to back it in Congress.
Peter Norton
>pno...@beaux.atwc.teradyne.com (Peter Norton) writes:
>> pr...@price.demon.co.uk writes:
>> >For those that want to know, here are the answers:
>> [faq-ola]
>>
>> have seen the true FAQ!
>>
>> many thanks.
>>
>> Well done!
>>
>> ----
>> "Bohm + Ockham => Everett" (chain smoking and driving a cadillac with horns?)
>
>the "one true faith". In it Mike (or whomever) makes some fantastic
>claims that may or may not be true depending on how litteraly one
>takes their axiomatic theories, but that's okay. On that count I
>certainly disagree that Mike is a crackpot, he's just too zealous to
>be objective (my spin).
>
>However, the above comment, which is indicative of the dogmatic
>viewpoints that supporters of the Everett "meta-theory" invariably
>seem to hold, is EXACTLY why the non-converts look at the Everett
>"movement" with such distain. Silly retrodictive arguments aside,
True enough, I am sorry to have tainted Mike's efforts with my own
peculiar enthusiasms. No doubt he is embarassed to have attracted such
a demented 'convert' as myself. Oh well, it is the occupational hazard
of any 'professor' to have to tolerate a few wild-eyed nuts in the back
row who come up after the lecture to propound their enthusiastic mistaken
extrapolations.
>until *unique* *predictive* tests demonstrate the reality of the
>Everett wavefunction, it remains in the arena of well-motivated
>spectulation (at least in a scientific context).
Indeed. But science is not the be-all and end-all of knowledge, much
less of wisdom. The whole western academic rat race has betrayed to
a large extent the search for self-knowledge. It is only accidentally
that we have stumbled on this clue to the link of Mind and Nature that
is revealed in the Everett metatheory. Left to the institutions of science,
it is guaranteed to go nowhere, except maybe as a slogan on a T shirt.
>"...it doesn't matter how beautiful your theory is, it doesn't matter
>how smart you are -- if it doesn't agree with experiment, it's wrong."
>
> - R.P. Feynman
I _have_ done the experiment, I do not speak from an armchair.
Unfortunately, it would be useless to 'publish' it, as well as being
impossible. Unfortunately, the nature of the experiment is such that it
can only be replicated on an individual basis. I'm sorry, that is just the
way it seems to be. If I described it, you would only laugh. If you did
not laugh, it would not be valid.
Cheers
---
"Relativity changed everything, except the way we think." - Einstein
Peter Norton
>>Everett wavefunction, it remains in the arena of well-motivated
>>spectulation (at least in a scientific context).
>
>Indeed. But science is not the be-all and end-all of knowledge, much
>less of wisdom. The whole western academic rat race has betrayed to
>a large extent the search for self-knowledge. It is only accidentally
>that we have stumbled on this clue to the link of Mind and Nature that
>is revealed in the Everett metatheory. Left to the institutions of science,
>it is guaranteed to go nowhere, except maybe as a slogan on a T shirt.
>
>>"...it doesn't matter how beautiful your theory is, it doesn't matter
>>how smart you are -- if it doesn't agree with experiment, it's wrong."
>>
>> - R.P. Feynman
>
>I _have_ done the experiment, I do not speak from an armchair.
>Unfortunately, it would be useless to 'publish' it, as well as being
>impossible. Unfortunately, the nature of the experiment is such that it
>can only be replicated on an individual basis. I'm sorry, that is just the
>way it seems to be. If I described it, you would only laugh. If you did
>not laugh, it would not be valid.
>
>Cheers
>
>---
>"Relativity changed everything, except the way we think." - Einstein
i.e. Change your mind, change your world.
---
"Time and space are modes by which we think,
they are not conditions in which we live."
- Einstein
"How can you be in two places at once, when you're really not anywhere at all?"
- Firesign Theatre
Michael Clive Price
> Silly retrodictive arguments aside, until *unique*
> *predictive* tests demonstrate the reality of the
> Everett wavefunction, it remains in the arena of
> well-motivated spectulation (at least in a scientific
> context).
That would be true *if* there was an alternative model to test
many-worlds against. But there isn't. Perhaps that's why
the guy in your sig supported many-worlds
Mike Price pr...@price.demon.co.uk
Matt McIrvin
Andy Boden <an...@henry.jpl.nasa.gov> wrote:
>However, the above comment, which is indicative of the dogmatic
>viewpoints that supporters of the Everett "meta-theory" invariably
>seem to hold, is EXACTLY why the non-converts look at the Everett
>"movement" with such distain.
Nonsense. Not all Everett supporters are dogmatic about it. I'm a
supporter of it, and I don't even believe it.
I think *most* non-converts look on it with disdain because they don't
know what it really is. They've read misleading accounts like Paul
Davies' in _Other Worlds_, or something similar, and think that
many-worlds involves some fantastically complicated cosmological
mechanism that spawns new spacetime manifolds whenever a special
"measurement event" occurs, which would be not only not better than a
collapse interpretation, but a good sight *worse*.
On the other hand, it does the notion no good to look on all competing
ones with sweeping disdain; not all such disdain is deserved.
--
Matt 01234567 <-- Indent-o-Meter
McIrvin ^ Harnessing tab damage for peaceful ends!
Andy Boden
> In article <36c9o7$e...@elroy.jpl.nasa.gov>,
> Andy Boden <an...@henry.jpl.nasa.gov> wrote:
>
> >However, the above comment, which is indicative of the dogmatic
> >viewpoints that supporters of the Everett "meta-theory" invariably
> >seem to hold, is EXACTLY why the non-converts look at the Everett
> >"movement" with such distain.
>
> Nonsense. Not all Everett supporters are dogmatic about it. I'm a
> supporter of it, and I don't even believe it.
>
As Justice Holmes said: "No generalization is completely true, not
even this one." Sorry to paint you with the same broad brush. But I
just have to ask, what does it mean to support something and not
believe it?
> I think *most* non-converts look on it with disdain because they don't
> know what it really is. They've read misleading accounts like Paul
> Davies' in _Other Worlds_, or something similar, and think that
> many-worlds involves some fantastically complicated cosmological
> mechanism that spawns new spacetime manifolds whenever a special
> "measurement event" occurs, which would be not only not better than a
> collapse interpretation, but a good sight *worse*.
Closer to the truth is having been repeatedly exposed to the Everett
evangelism, retrodictive nonsense, and all the rest. *Certain*
elements in Everett camp are ready to claim victory when no unique
quantitative prediction has ever been made by the meta-theory, let
alone tested by experiment. As long as Everett supporters are willing
to be intellectually honest enough to admit this I have no problem.
As long as certain members of the chosen few allow their theoretical
prejudices to overrun their objectivity, then I feel compelled to take
up the issue (when it would be a lot smarter to just avoid the whole
conflagration).
If the Everett interpretation is true, fine. But in science the issue
isn't settled until it's tested by experiment, despite however
compelling one finds one set of arguments or the other. It would be
best not to lose sight of that.
>
> On the other hand, it does the notion no good to look on all competing
> ones with sweeping disdain; not all such disdain is deserved.
Everett supporter's distain -- who cares? Just a request that the
supporters be honest and ethical.
Michael Kagalenko
Michael Clive Price <pr...@price.demon.co.uk> wrote:
]
]Matt McIrvin writes:
]> I think *most* non-converts look on it with disdain because they don't
]> know what it really is. They've read misleading accounts like Paul
]> Davies' in _Other Worlds_, or something similar, and think that
]> many-worlds involves some fantastically complicated cosmological
]> mechanism that spawns new spacetime manifolds whenever a special
]> "measurement event" occurs, which would be not only not better than
]> a collapse interpretation, but a good sight *worse*.
]Exactly. That is what concerns me. Not that most people don't believe
]in Everett's many-worlds, but that they (mostly) don't even understand
]it. It is this lack of comprehension that my FAQ seeks to address.
I think I do understand Everett's interpretation. What I don't understand
is why some people are impressed by it. It is mathematically trivial;
it is not new word in philosophy either. And it does not seem to me
relevant to physics, since all physical consequences of it are identical to
Copenhahen interpretaion.
Michael Clive Price
Date: Mon, 10 Oct 94 09:31:39 GMT
Reply-To: pr...@price.demon.co.uk
X-Newsreader: Demon Internet Simple News v1.29
Lines: 66
Matt McIrvin writes:
> I think *most* non-converts look on it with disdain because they don't
> know what it really is. They've read misleading accounts like Paul
> Davies' in _Other Worlds_, or something similar, and think that
> many-worlds involves some fantastically complicated cosmological
> mechanism that spawns new spacetime manifolds whenever a special
> "measurement event" occurs, which would be not only not better than
> a collapse interpretation, but a good sight *worse*.
Exactly. That is what concerns me. Not that most people don't believe
in Everett's many-worlds, but that they (mostly) don't even understand
it. It is this lack of comprehension that my FAQ seeks to address.
Michael Price pr...@price.demon.co.uk
john baez
>In article <36c9o7$e...@elroy.jpl.nasa.gov>,
>Andy Boden <an...@henry.jpl.nasa.gov> wrote:
>>However, the above comment, which is indicative of the dogmatic
>>viewpoints that supporters of the Everett "meta-theory" invariably
>>seem to hold, is EXACTLY why the non-converts look at the Everett
>>"movement" with such distain.
>Nonsense. Not all Everett supporters are dogmatic about it. I'm a
>supporter of it, and I don't even believe it.
Me too - and me neither. Once, as a hot-headed youth, I would argue
endlessly with anyone about interpretations of quantum mechanics, trying
my best to convince everyone of Everett's ideas. (Some people here on
sci.physics will remember.) Now I am post-Everettian, in the sense
that, having my original worries about quantum mechanics dispelled, I no
longer care very much about these issues, and pretty much any
interpretation of quantum mechanics is okay with me as long as you 1)
don't bother me about it, and 2) get the right answers to actual physics
problems.
Now, there are always more things to worry about any theory. These
days, thanks to the salutary influence of James Dolan, my main worry
about the foundations of quantum mechanics is probably that Hilbert
spaces don't form a Cartesian closed category (and, more importantly, we
don't really know an alternative category-theoretic language that does
for quantum logic what Cartesian closed categories do for so many other
forms of logic).
I threw that last bit in to change the subject to something more
interesting than the refried interpretation-of-QM debate. Maybe I
should explain it a wee bit, in the hopes that other, more knowledgeable
folks will explain it better. A category is a formalization of any
situation in which there are OBJECTS and MORPHISMS between objects, such
that one can compose morphisms in an associative way, and such that each
object has an "identity morphism" from it to itself that acts as the
identity should for composition.
This is a bare-bones sort of mathematical structure, but the world of
set theory has a lot more to it. I.e., there is a category, Set, whose
objects are sets, and such that for any pair of sets x and y, the
morphisms from x to y are just the functions from x to y. However, Set
has a lot extra structure. For example, we can take cross products of
sets. A category which has a notion of a "product" of objects
(satisfying various nice properties) is called a "monoidal" category.
Even more curiously, the set Hom(x,y) of all morphisms from x to y is a
*set*, i.e., it is again an OBJECT in Set. (To see just how special
this familiar fact really is, compare the category Group in which the
objects are groups and the morphisms are homomorphisms. The set
Hom(x,y) of homomorphisms from a group x to a group y is *not* an object
in Group, that is, it's not a group - at least not in any useful sort of
way.) A category in which we can think of Hom(x,y) as again an object
in the category is called "closed". Of course, there is a precise
definition, which I'm not giving here, since I'm not being paid enough
for that. The point I want to make is that one reason why the category
Set is a "world unto itself" which we might be perfectly happy never
leaving is because it is closed in this technical sense.
In fact, Set has various other properties... the product and the Hom get
along in a nice way, and so on, in a way category theorists summarize by
saying that it's a "Cartesian closed category". The cool thing about
this is that there are *other* Cartesian closed categories, other
worlds, as it were, that are different from Set but also big and roomy
enough to live in quite happily. Less poetically, the point is that
they share so many formal properties with Set that one can do many sorts
of the things one does in Set, even though they may be very different in
flavor. For example, the worlds of intuitionistic logic is also gives
you a Cartesian closed category. It is even possible to make up a nice
Cartesian closed category of certain topological spaces (the "compactly
generated" ones, for example).
Unfortunately, quantum theory, in its various formulations, appears
not to give a Cartesian closed category. (I'd love to be corrected
here. There are lots of ways one might try. Certainly the category of
Hilbert spaces isn't Cartesian closed, nor I think is the category of
complete orthocomplented lattices.) This is why quantum logic (which
comes in various flavors) doesn't have quite the grandeur of classical
logic - one keeps needing to "pop out of it" to do more complicated
forms of reasoning.
I suppose that this could be largely an artifact of how we are so used
to the classical world that we have not formulated logic in such a way
that quantum theory is built in. (Indeed, lots of people will probably
jump in here and argue that doing that would be a really bad idea.) So
while we can "reason quantumly" a bit using quantum logic, when we do
complicated calculations we always "reason classically" in a
meta-language like set theory. Maybe there's a quantum analog of
Cartesian closed categories... or perhaps just as likely, there may be
some big aspects of this business we don't understand yet.
Benjamin J. Tilly
t...@math.Princeton.EDU (Terry Tao) writes:
[...]
> But yes, apart from some problems with quantum observers, the interpretations
> are theoretically equivalent. But then again, so are the oft-quoted theories
> of Ptolemian (sic?) epicycles and the Copernican model.. :-)
Not quite. There are a number of differences between the two models
when you know a bit of physics. One is stellar aberration. A second is
stellar parallax. The third is that the old pendulum experiment where
the pendulum appears to turn, gives different results. (There are two
variations of the geocentric theory, one says that the pendulum should
not turn, the other says that it should, but it should be off by about
a third of a percent from the figure that is observed.)
And of course the Copernican "interpretation" is better suited to
handling advances such as Newton's theory of gravity...) Even going
into less detail, the Copernican version makes clear predictions about
the phases of Venus, and what happens when Venus passes in front of the
Sun...
And, of course, my feeling about interpretational questions is similar,
they may be the same for basic stuff, but they are different when you
begin to try to add more to the topic...
Cheers,
Ben Tilly
Matthew P Wiener
> Why is this a worry about quantum logic, instead of a worry
>about Cartesian closed categories?
Because CCCs are the way to go.
It's sort of like fuzzy sets: the idea is not very good, since it
doesn't lead to any natural category to work in.
--
-Matthew P Wiener (wee...@sagi.wistar.upenn.edu)
David B. Benson
Ieke Moerdijk and Gonzalo E. Reyes
Models for Smooth Infinitesimal Analysis
Spring-Verlag, 1991
ISBN 0-387-97489-X
treats this problem in considerable detail, producing a solution which will
appeal to many. [I always wanted the Dirac delta function to be a
legitimate function. It is in this book.] Here is a quote from the
introduction, for which you need to know that A^B is notation for the set of
functions from B to A:
The need for a cartesian closed category of smooth spaces
and smooth maps has been repeatedly pointed out in connection
to physics. We mention the follwoing considerations, due to
Lawvere (1980): The motion of a certain body B (for example.
a 0-dimensional system of particles, a 1-dimensional elastic
cord, a 2-dimensional flexible shell, a 3-dimensional solid)
is often represented by a map
q: TxB --> E
where T is (the 1-dimensional space to measure) time, and E
is the ordinary flat 3-dimensional space. Thus, the motion may
be thought of as assigning a couple (time, particle of B) the
corresponding place in E during the motion.
For other purposes, however, it is useful to consider motion
as a map
Q: B --> E^T
which assigns to each particle of B its path through E, where
E^T is the space of (smooth) paths. The action of the vector
space V of translations of the flat space E allows us to define
a map
(.): E^T --> V^T
using Newton's notation. [i.e., the first derivative]. By
composing with Q we obtain a new map which, in turn, gives us
(by adjunction) the velocity map
v: TxB --> V
of the motion q.
Still another way of considering motion is necessary for some
purposes, namely as a map
R: T --> E^B
which assigns to a time the (smooth) palcement of the body in
space at that time. ...
The various connections between these ways of regarding motion
should be expressed precisely by the adjunctions available from
the cartesian closed structure of a category of smooth spaces
and smooth maps. In the words of Lawvere: "The E, B, T
transforms (i.e., the adjunctions) are <<more>> (at least as)
fundamental as any particular determination of the objects as
"consisting" of points, opens, paths, etc., and indeed any such
determination which does not admit these transformations is
ultimately of only specialized interest".
The second limitation of the theory of manifolds ...
Well, you see the gist. This book includes both nilpotent and invertible
infinitesimals within the mathematical framework. Since the framework
is topos theory, the associated logics are topos logics -- sometimes
called geometric logics. The logic is treated briefly in an appendix,
but for an introduction one needs a different text.
john baez
>In article <1994Oct12.1...@cs.sfu.ca>, jamie@cs (Jamie Andrews) writes:
>> Why is this a worry about quantum logic, instead of a worry
>>about Cartesian closed categories?
>Because CCCs are the way to go.
>It's sort of like fuzzy sets: the idea is not very good, since it
>doesn't lead to any natural category to work in.
This reasoning, while convincing to a category theorist, and (as a
junior category theorist myself) even to me to some extent, is of course
unlikely to convince someone unfamiliar of the subject. So perhaps you
could expound to the ignorant a bit on why CCCs are "the way to go".
Only if you feel like it.....
Jack Sarfatti
>
>Me too - and me neither. Once, as a hot-headed youth, I would argue
>endlessly with anyone about interpretations of quantum mechanics, trying
>my best to convince everyone of Everett's ideas. (Some people here on
>sci.physics will remember.)
Speedup of the aging process? This goes against the twin paradox. So John
could not have been abducted in a UFO and gone to Zeta Rediculi and back
again. Is there any traversable wormhole process (assuming CPC wrong) that
could account for the aged Baez appearing among us? Yes, if he went to
future and aged and then returned from the future.
>Now I am post-Everettian, in the sense
>that, having my original worries about quantum mechanics dispelled, I no
>longer care very much about these issues, and pretty much any
>interpretation of quantum mechanics is okay with me as long as you 1)
>don't bother me about it, and 2) get the right answers to actual physics
>problems.
Alas! The tragedy of senility in one with so much promise! :-)
>
>Now, there are always more things to worry about any theory. These
>days, thanks to the salutary influence of James Dolan, my main worry
>about the foundations of quantum mechanics is probably that Hilbert
>spaces don't form a Cartesian closed category (and, more importantly, we
>don't really know an alternative category-theoretic language that does
>for quantum logic what Cartesian closed categories do for so many other
>forms of logic).
??????? This may explain why orthodox quantum theory is linear and
unitary because it excludes Godelian self-reference required for
"conscious" organizations of matter that measure themselves.
>
>I threw that last bit in to change the subject to something more
>interesting than the refried interpretation-of-QM debate. Maybe I
>should explain it a wee bit, in the hopes that other, more knowledgeable
>folks will explain it better. A category is a formalization of any
>situation in which there are OBJECTS and MORPHISMS between objects, such
>that one can compose morphisms in an associative way, and such that each
>object has an "identity morphism" from it to itself that acts as the
>identity should for composition.
Godelian self-reference - Hofstadter's strange loop? Any application to
OLE 2? Any other software applications?
>
>This is a bare-bones sort of mathematical structure, but the world of
>set theory has a lot more to it. I.e., there is a category, Set, whose
>objects are sets, and such that for any pair of sets x and y, the
>morphisms from x to y are just the functions from x to y. However, Set
>has a lot extra structure. For example, we can take cross products of
>sets. A category which has a notion of a "product" of objects
>(satisfying various nice properties) is called a "monoidal" category.
Phase entanglement needs this kind of tensor product for quantum nonlocality
- right?
>
>Even more curiously, the set Hom(x,y) of all morphisms from x to y is a
>*set*, i.e., it is again an OBJECT in Set.
This sounds like Godelian self-reference also??????
>(To see just how special
>this familiar fact really is, compare the category Group in which the
>objects are groups and the morphisms are homomorphisms. The set
>Hom(x,y) of homomorphisms from a group x to a group y is *not* an object
>in Group, that is, it's not a group - at least not in any useful sort of
>way.)
Well this sounds like the split between observer and observed in orthodox
quantum theory which is linear unitary with no communication on the phase
entangled nonlocal quantum connections - apparently.
What happens if we add the nonunitary irreversible arrow of time
so we go to category semi-Group - will the corresponding Hom(x,y)
now be an "object"?
>A category in which we can think of Hom(x,y) as again an object
>in the category is called "closed".
Will: group + arrow of time -> semigroup effect "closure"?
>Of course, there is a precise
>definition, which I'm not giving here, since I'm not being paid enough
>for that. The point I want to make is that one reason why the category
>Set is a "world unto itself" which we might be perfectly happy never
>leaving is because it is closed in this technical sense.
Is this Set the Egyptian God of Consciousness? :-)
>
>In fact, Set has various other properties... the product and the Hom get
>along in a nice way, and so on, in a way category theorists summarize by
>saying that it's a "Cartesian closed category". The cool thing about
>this is that there are *other* Cartesian closed categories, other
>worlds, as it were, that are different from Set but also big and roomy
>enough to live in quite happily. Less poetically, the point is that
>they share so many formal properties with Set that one can do many sorts
>of the things one does in Set, even though they may be very different in
>flavor. For example, the worlds of intuitionistic logic is also gives
>you a Cartesian closed category. It is even possible to make up a nice
>Cartesian closed category of certain topological spaces (the "compactly
>generated" ones, for example).
>
>Unfortunately, quantum theory, in its various formulations, appears
>not to give a Cartesian closed category. (I'd love to be corrected
>here. There are lots of ways one might try. Certainly the category of
>Hilbert spaces isn't Cartesian closed, nor I think is the category of
>complete orthocomplented lattices.) This is why quantum logic (which
>comes in various flavors) doesn't have quite the grandeur of classical
>logic - one keeps needing to "pop out of it" to do more complicated
>forms of reasoning.
Well, this corresponds to the linear unitary approximation to the final
theory of the world. Stapp in July 94 Phys Rev A points the way to get
a generalized QM that will be a closed category that I precognize will
unify the physics of mind with that of gravitation - showing how the the
"Mind of God" (wave function of the universe) really did The Creation!
>
>I suppose that this could be largely an artifact of how we are so used
>to the classical world that we have not formulated logic in such a way
>that quantum theory is built in. (Indeed, lots of people will probably
>jump in here and argue that doing that would be a really bad idea.)
No, it's a really good idea - key is Stapp's July 94 paper in Phys Rev A.
>So
>while we can "reason quantumly" a bit using quantum logic, when we do
>complicated calculations we always "reason classically" in a
>meta-language like set theory. Maybe there's a quantum analog of
>Cartesian closed categories... or perhaps just as likely, there may be
>some big aspects of this business we don't understand yet.
This is the first really important profound original paper that John
Baez has produced. See - travel to the future and back is really good
if you want to be a Genius! :-)
From the Future with a Big Slurpy Kiss from Mr Omega Point
Amazing Jack Star
Cosmic Intelligence Agency
not to be confused with the
Comic Intelligence Agency
in a parallel universe.
>
>
>
>
>
john baez
> This reminds me of one of my many confusions. How can I actually tell
>if Hom(x,y) is a set? Given any "thing", I might be able to tell whether
>it is in Hom(x,y) or not, but the question of whether two elements of
>Hom(x,y) are equal may not be computable. What's the definition of a set
>anyway?[*] And why is mathematics built on sets rather than aggregates
>(or bags or whatever you call "sets which might have duplicate elements")?
>Also in the definition of a category, is OBJECTS a set, something else or
>primitive?
Lots of questions.
1. The usual way to tell if something is a set is to read books on set
theory, learn the axioms of set theory, and get good at proving things
like "there is a set such that blah-di-blah holds". Consider for example the
usual ZFC axioms. There is no "definition" of a set here; rather, there
are a bunch of axioms that say stuff like (and here I will be vague ---
you really have to read a book on this stuff):
There is a set with no members. (the "empty set")
If S and T are sets, there is a set whose members are those things that
are members of either S or T. (the "union")
If S is a set and P is a property that we can write a "formula" for,
there is a set of all members of S having property P. (this is the
"selection" axiom or "Aussonderungsaxiom".)
2. Why is mathematics built on sets rather than "bags," also known as
multisets? Because that's what people felt like doing. I don't know if
anyone has tried very hard to built a foundations of mathematics using
multisets; it might be a bit hard to do it in a slick way.
3. In a category, OBJECTS is a class, not a set. Any formula defines a
class, but not necessarily a set. E.g., the formula "x is a set"
defines the class of all sets, but not a set of all sets, since the
latter would get us in trouble with Rusell's paradox. That's why people
use the Aussonderungsaxiom instead of saying that every formula defines
a set!! So, to have a category whose objects are all sets, we need to
allow the possibility of there being a class rather than a set of
objects.
Things get a little hairier when we want to work with the category of
all categories. One standard approach is to define a "small" category
to be a category with a set of objects, and then talk about the category
Cat of all small categories. (This category is of course not a small
category.) We can still get in trouble along these Russellian lines at
various other points, and one approach people use to deal with this
stuff if they are getting really heavily into it is to work with
"universes" --- for which I refer you to the book Categories for the
Working Mathematician, by Saunder Mac Lane. (At least that'll get you
started.)
>|The golden rule of modern mathematics is that life takes place within
>|-- and between -- categories.
>| (This is actually from ftp://math.ucr.edu/baez/categories)
> Here I also have the feeling that I'm missing something. Categories
>seem like a very nice way of organizing things, but I don't understand
>why (or to what extent) *all* useful structures are expected to be categories
>(e.g. metric spaces seem useful but they apparently don't form a nice
>category). Of course, this means that I also don't understand why
>cartesian closed categories are so great either... [**]
Sure, there is a category Met whose objects are metric spaces and whose
morphisms are continuous maps. What exactly do you mean by saying it's
not a "nice" category?
Cartesian closed categories, as I tried to indicate, are great because
you can do in them most of the things mathematicians always want to do. Of
course, it took category theorists a long time to isolate the essence of
(much of) what it was that mathematicians want to do in *any* sort of
situation! I guess you have to spend some time working on various
branches of math, and thinking about it the way that category theorists
have learned to do, to see that all sorts of familiar constructions are
really just examples of very general things called limits and colimits,
and that it's very nice when there's also a monoidal structure and
internal "Hom" that get along nicely with each other and the limits and
colimits. The book by Mac Lane does its best to illustrate how many
different things are really just examples of this. However, it's the
kind of thing one has to work on to really appreciate. Think of it as
part of ones "meta-education" in mathematics.
>[*] I actually own a book on axiomatic set theory, but it has a chapter
> called "Aussonderungstheorem. Intersection." I decided that this
> was a bad sign.
Well, they probably just used slightly different axioms so that the
above "Aussonderungsaxiom" becomes a theorem. "Aussonderung" just means
"selection" in German, it's no big deal.
>[**] By the way, do you recommend a book on category theory? Do you like
> "Categories for the Working Mathematician" ?
Yes, in small doses. Basically, you first need to learn what a category
is, what a functor is, and what a natural transformation is. Then you
need to spend a year or so learning to NOTICE in every mathematical
situation when you have a category, or a functor, or a natural
transformation going on. They go on all the time, but you need to learn
to see it. Then you need to learn the definitions of products, coproducts,
equalizers, coequalizers, pushouts and pullbacks. Then spend a year
learning to notice THEM. Again, they are everywhere, and they aren't
complicated; it's just a matter of noticing them. Then you need to
learn the definitions of limits, colimits, and adjoint functors, and
spend a year getting to see THEM.
Unless you completely succumb to the lure of category theory and fall
wildly in love with these ideas, you should have these be back-burner
projects. I only got rolling on this stuff very recently, in part
because I realized that category theory holds the key to topological
quantum field theories, which I happen to be interested in.
Michael Kagalenko
Terry Tao <t...@math.Princeton.EDU> wrote:
]In article <37civ2$4...@lynx.dac.neu.edu> mkag...@lynx.dac.neu.edu (Michael Kagalenko) writes:
]>]
]>]Exactly. That is what concerns me. Not that most people don't believe
]>]in Everett's many-worlds, but that they (mostly) don't even understand
]>]it. It is this lack of comprehension that my FAQ seeks to address.
]>
]> I think I do understand Everett's interpretation. What I don't understand
]> is why some people are impressed by it. It is mathematically trivial;
]> it is not new word in philosophy either. And it does not seem to me
]> relevant to physics, since all physical consequences of it are identical to
]> Copenhahen interpretaion.
]I probably shouldn't get involved in this, but..
]
]My understanding of this is that Many-Worlds and the Copenhagen
]interpretation (requiring the additional collapse postulate) give
]predictions that agree when the experiment and observer are clearly
]seperable, and the experiment is microscopic and the observer is
]macroscopic. If the observer though is also subject to interference
]effects - for example, if its/his/her memory is totally reversible -
]then Copenhagen becomes a bit vague on what happens, whereas Many Worlds
]gives a definite prediction.
Thanks for reply, but it is not quite clear to me what you mean. If
observer is subject to interference effects, then he is not observer
in the Copenhagen sense - or I am wrong here ?
]The aesthetic appeal of MW over Copenhagen is a completely seperate
]issue, of course. The removal of the most irksome postulate (collapse)
]from Copenhagen gives almost exactly the same theory except for the fact
]that the wavefunction of the universe the observer observers is now only a
]personal projection of the "real universal" wavefunction and not the
]ultimate depiction of reality in itself. So if one is seeking the most
]beautiful set of laws needed to describe the universe, MW seems better.
As regards the question of beauty, it seems to me that Occam razor
clearly denies to MW the status of Beautiful Theory.
]But yes, apart from some problems with quantum observers, the interpretations
]are theoretically equivalent. But then again, so are the oft-quoted theories
]of Ptolemian (sic?) epicycles and the Copernican model.. :-)
I don't understand you again - it takes infinite amount of epicycles to
emulate ellips, doesn't it ? So, it seems to me you are stretching
the meaning of "equivalent" here.
Saul Youssef
| John Baez writes:
|
|I threw that last bit in to change the subject to something more
|interesting than the refried interpretation-of-QM debate. Maybe I
|should explain it a wee bit, in the hopes that other, more knowledgeable
|folks will explain it better.
|
|A category is a formalization of any
|situation in which there are OBJECTS and MORPHISMS between objects, such
|that one can compose morphisms in an associative way, and such that each
|object has an "identity morphism" from it to itself that acts as the
|identity should for composition.
|
|This is a bare-bones sort of mathematical structure, but the world of
|set theory has a lot more to it. I.e., there is a category, Set, whose
|objects are sets, and such that for any pair of sets x and y, the
|morphisms from x to y are just the functions from x to y. However, Set
|has a lot extra structure. For example, we can take cross products of
|sets. A category which has a notion of a "product" of objects
|(satisfying various nice properties) is called a "monoidal" category.
|
|
|Even more curiously, the set Hom(x,y) of all morphisms from x to y is a
|*set*, i.e., it is again an OBJECT in Set.
|
This reminds me of one of my many confusions. How can I actually tell
if Hom(x,y) is a set? Given any "thing", I might be able to tell whether
it is in Hom(x,y) or not, but the question of whether two elements of
Hom(x,y) are equal may not be computable. What's the definition of a set
anyway?[*] And why is mathematics built on sets rather than aggregates
(or bags or whatever you call "sets which might have duplicate elements")?
Also in the definition of a category, is OBJECTS a set, something else or
primitive?
|
|The golden rule of modern mathematics is that life takes place within
|-- and between -- categories.
|
| (This is actually from ftp://math.ucr.edu/baez/categories)
|
Here I also have the feeling that I'm missing something. Categories
seem like a very nice way of organizing things, but I don't understand
why (or to what extent) *all* useful structures are expected to be categories
(e.g. metric spaces seem useful but they apparently don't form a nice
category). Of course, this means that I also don't understand why
cartesian closed categories are so great either... [**]
|
|I suppose that this could be largely an artifact of how we are so used
|to the classical world that we have not formulated logic in such a way
|that quantum theory is built in. (Indeed, lots of people will probably
|jump in here and argue that doing that would be a really bad idea.) So
|while we can "reason quantumly" a bit using quantum logic, when we do
|complicated calculations we always "reason classically" in a
|meta-language like set theory. Maybe there's a quantum analog of
|Cartesian closed categories... or perhaps just as likely, there may be
|some big aspects of this business we don't understand yet.
|
If you like quantum logic, you might like this:
If you get quantum mechanics by modifying probability theory, you find
that some sets of propositions support old fashioned probabilities and
some do not. However, supporting old fashioned probabilities is
equivalent to being able to repeatedly assign boolean values to
all the propositions in a way which agrees with experimental results.
This means that the modified probability theory implies a failure of
contrafactual definiteness (which I guess would be interepreted as a
"failure of logic" by quantum logic fans). So maybe modifying probability
theory is related to one of the quantum logic proposals.
Cheers,
Saul Youssef
[*] I actually own a book on axiomatic set theory, but it has a chapter
called "Aussonderungstheorem. Intersection." I decided that this
was a bad sign.
[**] By the way, do you recommend a book on category theory? Do you like
"Categories for the Working Mathematician" ?
------------------------------------------------------------------------------
"...it doesn't matter how beautiful your theory is, it doesn't matter
how smart you are -- it's wrong."
- S. Youssef
Paul Budnik
Saul Youssef (you...@ibm7.scri.fsu.edu) wrote:
: If you get quantum mechanics by modifying probability theory, you find
: that some sets of propositions support old fashioned probabilities and
: some do not.
That is false. Bohms model of QM relies entirely on classical probability
theory and logic. What you find is certain predictions of QM lead to
conclusions about locality that many physicists do not believe. So they
want to challenge the conventional laws of probability to avoid
these unpleasant conclusions.
: However, supporting old fashioned probabilities
`old fashion probabilities' i. e. the kind that everyone doing
statistical analysis uses unless they want to rationalize away
some of the implications of QM.
: is
: equivalent to being able to repeatedly assign boolean values to
: all the propositions in a way which agrees with experimental results.
: This means that the modified probability theory implies a failure of
: contrafactual definiteness (which I guess would be interepreted as a
: "failure of logic" by quantum logic fans). So maybe modifying probability
: theory is related to one of the quantum logic proposals.
Quantum mechanics is built entirely on classical logic, classical
mathematics and classical probability theory. It all works perfectly
it just leads to unpleasant conclusions. Quantum logic and nonstandard
probability are various feeble attempts to avoid those conclusions.
They need to do a great deal more than avoid unpleasant conclusions
before they have any credibility in my mind. They must show how to
create the predicted results without nonlocal causal mechanisms. That I
think is impossible and for this reason history's verdict on
quantum logic and nonstandard probability theory will be that it was
all so much nonsense.
Paul Budnik
Jamie Andrews
>These
>days, thanks to the salutary influence of James Dolan, my main worry
>about the foundations of quantum mechanics is probably that Hilbert
>spaces don't form a Cartesian closed category (and, more importantly, we
>don't really know an alternative category-theoretic language that does
>for quantum logic what Cartesian closed categories do for so many other
>forms of logic).
Why is this a worry about quantum logic, instead of a worry
about Cartesian closed categories?
--Jamie.
james dolan
>|
>|Sure, there is a category Met whose objects are metric spaces and whose
>|morphisms are continuous maps. What exactly do you mean by saying it's
>|not a "nice" category?
>|
> I guess the idea is that it would be "nice" to have morphisms that
>reflect the greater structure of Met compared to Topological Spaces.
>I got this complaint from Geroch ("Mathematical Physics") who then
>introduces Uniform Spaces as the "categorization of a metric space."
actually there has been a certain amount of significant work done on
categories of metric spaces where the morphisms preserve more of the
structure than arbitrary continuous maps do. in fact, metric spaces
themselves can be seen as categories of a sort (specifically, as
special cases of "categories enriched over the monoidal closed
category of positive real numbers"), and from this point of view the
distance-decreasing maps appear as the (again, "enriched") functors
between them. see some paper by lawvere with the word "metric spaces"
in the title for details.
(beware the "level shift" that just happened in the above paragraph;
first we were talking about metric spaces as objects in a category,
and then the discussion shifted to thinking of metric spaces _as_
categories. this tends to happen fairly often in category theory.)
Paul Budnik
: So
: while we can "reason quantumly" a bit using quantum logic, when we do
: complicated calculations we always "reason classically" in a
: meta-language like set theory.
What do you mean by `"reason quantumly" a bit using quantum logic'?
Paul Budnik
Falko Spiller
is it possible to work that out. or point me to a primer. i dont see the
problem with nonCCCs. falko (f...@thp.uni-koeln.de)
--
Falko Spiller
Uni-Koeln, Inst.f.Theo.Physik
e-mail: f...@thp.uni-koeln.de
(talk: f...@sunXX.thp.uni-koeln.de
with sunXX= sun0..sun14, mostly sun3)
Saul Youssef
|Saul Youssef (you...@scri.fsu.edu) wrote:
|
|: If you get quantum mechanics by modifying probability theory, you find
|: that some sets of propositions support old fashioned probabilities and
|: some do not.
|
|
Greetings Paul;
I suppose I've made my fair share of unsubstantiated claims in my
life, but this one actually has a proof (and it doesn't have anything to
do with Bohm.).
|
|relies entirely on classical probability
|theory and logic. What you find is certain predictions of QM lead to
|conclusions about locality that many physicists do not believe. So they
|want to challenge the conventional laws of probability to avoid
|these unpleasant conclusions.
|
Those dastardly guys!
|
|...Quantum logic and nonstandard probability are various feeble attempts to
|avoid those conclusions.
|
| ...history's verdict on quantum logic and nonstandard probability theory
|will be that it was all so much nonsense.
|
History may or may not favor these ideas, but at least they are
definite proposals.
Even if you want to show that a theory T is wrong, you have to be
willing to argue "Suppose T is true, then .... =><=." But if you
can't even bring yourself to suppose T, you're pretty much stuck.
Saul
----
BEGIN JOKE:
"...it doesn't matter how beautiful your theory is, it doesn't matter
how smart you are, it doesn't matter if it agrees with experiment -- it's wrong."
- P.Budnik
END JOKE.
Peter Norton
well, here is why at least one crackpot, myself, is impressed:
It has a lot of explanatory power for the age-old trans-philosophical
human conundrums of how subjective apparent individuality can coexist
with actual enlightened unity. I know many will say this is rubbish
(if they are polite), and unjustified extrapolation, and new-age soft-
headedness etc.etc., but nonetheless, I am impressed.
For me, personally, it also has a lot of explanatory power for many
anecdotal collections of altered human experience such as are found
in many old wisdom traditions: Gnostic, Sufic, Shamanic, Poetic, Ecstatic, etc.
Granted: this explanatory power is 'valid' for me alone, it cannot be
formulated in such a way that would satisfy any scientist who insists on
repeatable phenomena independent of observers to test new theoretical
predictions, since humans are not repeatable phenomena independent of
observers, and the prediction is not new, or even definite, i.e. all
things are predicted!
But it seems to be in keeping with the great scientific tradition where a new
theory will explain previous phenomena better than the previous
theory (in this case - religious 'theories' of 'angels/gods/God/etc.'),
which is now obsolete, but can be reduced to a special case of
the new theory under certain, restrictive circumstances. The paradigm
of this being Newton->Einstein.
(loosely speaking of Many Worlds as a 'theory', which is controversial,
I know)
The big problem is, of course, that the old obsoleted theories are in
the realm of religion, which gives a lot of people heartburn when it is
time to cease cherishing these old opinions. Not that their old traditions
were 'invalid', their experiential discoveries remain just as valid as ever,
it is just that their opinions about them have to grow a little.
i.e. it is time for new bathwater, but the baby remains.
Another thing about Many Worlds that impresses me is that it seems to confirm
the intuition found in many of these ancient traditions
that Mind is a lot more than discursive reasoning, that it penetrates the
very small, the very large, the future, the past, and conditions the
foundations of reality in a subtle, but essential way. And that this
aspect of Mind is 'revealed' only when 'measurements/observations' cease.
This point is a valuable contribution, I think, to the Many Worlds meta-theory
from the ancient traditions: i.e. Many Worlds is focused squarely on
the 'measurement event', but what are the implications of Many Worlds
for 'reality' prior to the 'measurement event'. Hmm? Well, it is my
humble, and perhaps confused, opinion that the old meditation traditions
have a thing or two to say about this point. Since basically, that is what
meditation is all about: the practice of 'non-observation', said differently
in different traditions, but experientially similar. OK, I can hear the
veins pounding in your temple: Yes! That *is* a reductionist statement! I
admit it! But what scientist can use the criticism of reductionism with a
clean conscience? Hmmm?
Unfortunately, whenever the word 'Mind' is used, paroxysms occur. Which
suddenly impedes the flow of meaning from words to the discursive,
associative, small-m mind. It would be a thankless, impossible task, to
come up with a better term, or to better 'define' all the connotations
of big-m Mind. So I won't even try. Except to say that the 'concept'
slowly accretes in an implicit, unformulable way after much inter-disciplinary
study and practice, so be patient.
So There. I've tried my best to be 'reasonable' and 'non-flaky'.
Flame away.
Cheers
---
"In searching for the truth, I came to see that I was merely
ceasing to cherish old opinions, one after the other,
until they were all forgotten."
-Sengtsan, 'Hsin Hsin Ming' (more or less)
Hans Moravec
mkag...@lynx.dac.neu.edu (Michael Kagalenko) writes:
> ...
> As regards the question of beauty, it seems to me that Occam razor
> clearly denies to MW the status of Beautiful Theory.
I guess by your way of looking at it, modern atomic theory fails Occam
horribly also. After all, it complicates a spoonful of the palpably
simple substance water to an outrageously complicated seething swarm of
10^24 (wow!) individual particles.
-- Hans Moravec CMU Robotics
Terry Tao
>]in Everett's many-worlds, but that they (mostly) don't even understand
>]it. It is this lack of comprehension that my FAQ seeks to address.
>
> I think I do understand Everett's interpretation. What I don't understand
> is why some people are impressed by it. It is mathematically trivial;
> it is not new word in philosophy either. And it does not seem to me
> relevant to physics, since all physical consequences of it are identical to
> Copenhahen interpretaion.
I probably shouldn't get involved in this, but..
My understanding of this is that Many-Worlds and the Copenhagen
interpretation (requiring the additional collapse postulate) give
predictions that agree when the experiment and observer are clearly
seperable, and the experiment is microscopic and the observer is
macroscopic. If the observer though is also subject to interference
effects - for example, if its/his/her memory is totally reversible -
then Copenhagen becomes a bit vague on what happens, whereas Many Worlds
gives a definite prediction.
The aesthetic appeal of MW over Copenhagen is a completely seperate
issue, of course. The removal of the most irksome postulate (collapse)
from Copenhagen gives almost exactly the same theory except for the fact
that the wavefunction of the universe the observer observers is now only a
personal projection of the "real universal" wavefunction and not the
ultimate depiction of reality in itself. So if one is seeking the most
beautiful set of laws needed to describe the universe, MW seems better.
But, if one actually wants to do calculations in the experiment-microscopic
observer-macroscopic world, Copenhagen seems to be easier to work with
(or at least is more familiar) - requiring no need to include the
observer in the wave-equation, for instance. As someone else pointed
out, it's kind of like the difference between the original Lorentzian
formulations of relativity with a preferred frame and the modern
description of spacetime with no preferred frame and the need to
take the status of the observer into account.
But yes, apart from some problems with quantum observers, the interpretations
are theoretically equivalent. But then again, so are the oft-quoted theories
of Ptolemian (sic?) epicycles and the Copernican model.. :-)
--
Terry Tao Math Dept., Princeton University (t...@math.princeton.edu)
i mi pacna da ni'o .i mi caki pacna di'e .itu'e ro ma'arbi'i ba galtu .i ro
cmana ba dizlo .i ro rufsu tumla ba xutla .i ro korcu pluta ba sirji .i le
la jegvon. kamymisno ba tolcanci .i ro se rectu ba simkansa viska ra
john baez
>|Sure, there is a category Met whose objects are metric spaces and whose
>|morphisms are continuous maps. What exactly do you mean by saying it's
>|not a "nice" category?
> I guess the idea is that it would be "nice" to have morphisms that
>reflect the greater structure of Met compared to Topological Spaces.
>I got this complaint from Geroch ("Mathematical Physics") who then
>introduces Uniform Spaces as the "categorization of a metric space."
Hmm. You can also work with the category whose objects are metric
spaces and whose morphisms are *uniformly* continous spaces, which is a
... what do they call it, full subcategory?... of the category of
uniform spaces. Perhaps the category of uniform spaces is a natural
kind of "completion" (in some sense I'm completely vague on) of Met.
Peter Norton
>
>"In searching for the truth, I came to see that I was merely
> ceasing to cherish old opinions, one after the other,
> until they were all forgotten."
>-Sengtsan, 'Hsin Hsin Ming' (more or less)
>
Of course, all my Many Wor(l)ds opinions that I so dearly cherish now,
must one day be forgotten also. There is no dissociation allowed.
Not even a little. No sniveling, either. Not even a little.
"The price of Freedom is eternal Vigilance."
-John F. Kennedy
john baez
Indeed. As I pointed out later in my post, I can imagine that the
answer to this problem would be a generalization of Cartesian closedness
suitable for handling quantum theory. I certainly DON'T think this
means quantum mechanics or quantum logic is "wrong" somehow, just that
it's insufficiently understood how it meshes with other ideas from
logic. I think some other people, like J. D., might feel differently,
perhaps because they know more about categories and less about quantum
theory than I do.
Saul Youssef
Although you're right that atomic theory was a gigantic leap, it
also explains a tremendous number of observations that no one knows
how to explain otherwise (and it also took a lot of evidence before
it was really accepted). On the other hand, a theory where a single
electron was made of 10^24 particles that didn't explain anything new
about electron behavior wouldn't be interesting at all. Cheers, Saul Youssef
Saul Youssef
|Sure, there is a category Met whose objects are metric spaces and whose
|morphisms are continuous maps. What exactly do you mean by saying it's
|not a "nice" category?
|
reflect the greater structure of Met compared to Topological Spaces.
I got this complaint from Geroch ("Mathematical Physics") who then
introduces Uniform Spaces as the "categorization of a metric space."
Thanks for the detailed responses.
Paul Budnik
: |Saul Youssef (you...@scri.fsu.edu) wrote:
: |
: |: If you get quantum mechanics by modifying probability theory, you find
: |: that some sets of propositions support old fashioned probabilities and
: |: some do not.
: |
: |That is false. Bohms model of QM ...
: |
: Greetings Paul;
: I suppose I've made my fair share of unsubstantiated claims in my
: life, but this one actually has a proof (and it doesn't have anything to
: do with Bohm.).
Perhaps I misinterpreted you or you could have been more clear. Certainly
there is nothing in QM that *requires* a modification to classical
probability theory as Bohm's theory shows.
: |
: |relies entirely on classical probability
: |theory and logic. What you find is certain predictions of QM lead to
: |conclusions about locality that many physicists do not believe. So they
: |want to challenge the conventional laws of probability to avoid
: |these unpleasant conclusions.
: |
: Those dastardly guys!
It is a matter of judgment as to how quickly you should challenge the
most basic principles of mathematics and philosophy. I am not above doing
that myself especially when it comes to completed infinite totalities. I
do not think the existing experimental results or the existing theory
provide a good basis for such a challenge.
: |
: |...Quantum logic and nonstandard probability are various feeble attempts to
: |avoid those conclusions.
: |
: | ...history's verdict on quantum logic and nonstandard probability theory
: |will be that it was all so much nonsense.
: |
: History may or may not favor these ideas, but at least they are
: definite proposals.
: Even if you want to show that a theory T is wrong, you have to be
: willing to argue "Suppose T is true, then .... =><=." But if you
: can't even bring yourself to suppose T, you're pretty much stuck.
I do not object to people trying out anything they choose. I think a
different approach is called for and I hope you do not object to my
having that opinion.
Whatever approach you favor you must be cautious in making claims about
what quantum mechanics *requires*. Many physicists have been extremely
sloppy about this. Neither quantum mechanics nor the existing experimental
results require that we abandon or modify classical logic or classical
probability theory.
: ----
: BEGIN JOKE:
: "...it doesn't matter how beautiful your theory is, it doesn't matter
: how smart you are, it doesn't matter if it agrees with experiment -- it's wrong."
: - P.Budnik
: END JOKE.
I am not amused.
I will say it doesn't matter how smart you are but only how beautiful your
theory is and how well it agrees with experiment.
Paul Budnik
Michael Clive Price
<781781...@price.demon.co.uk> <37civ2$4...@lynx.dac.neu.edu>
Date: Thu, 13 Oct 94 08:31:14 GMTLines: 17
Michael Kagalenko writes:
> I think I do understand Everett's interpretation. What I don't
> understand is why some people are impressed by it. It is
> mathematically trivial; it is not new word in philosophy either.
You seem to be saying that you are happy with the standard Copenhagen
interpretation in which case, fine. I'm not and neither are *lots* of
other people.
> And it does not seem to me
> relevant to physics, since all physical consequences of it are
> identical to Copenhahen interpretaion.
There is no agreement in the Copenhagen camp about the outcome of some
experiments which involve interference effects between observers.
Many-worlds accepts that observers are quantised like any other object,
so these interference effects are always present, to some extent.
Michael Price pr...@price.demon.co.uk
john baez
>Quantum logic and nonstandard
>probability are various feeble attempts to avoid those conclusions.
Quantum logic is not a "feeble attempt to avoid unpleasant conclusions".
You are projecting your own feverish worries onto other people. It is a
perfectly fine branch of lattice theory, which sheds a fair amount of
light on the structure of quantum mechanics. People who actually want
to know something about it should not rely on hearsay, but instead read
something like:
The Logico-algebraic approach to quantum mechanics / edited by C. A. Hooker.
Dordrecht ; Boston : D. Reidel Pub. Co., [1975]-1979.
I think there will be a very nice paper in the AMS Bulletin about new results
on this subject in a while, too.
Hans Moravec
>]Michael Kagalenko writes:
>
> I don't understand what you are saying here. In my understanding
> of Copenhagen interpretation observer is not subject to interference
> by definition; if something is subject to interference, it is part
> of the system.
That's where Everett beats Bohr, Occam-wise. Unlike Copenhagen, MW
does not introduce, as a basic concept, the unnecessary idea of an
observer, who, unlike everything else, is not described by a
superposable wave function.
Stop multiplying concepts needlessly!
Many worlds : few concepts !
john baez
>John Baez writes:
> The set Hom(x,y) of homomorphisms from a group x to a group y is
> *not* an object in Group, that is, it's not a group - at least not
> in any useful sort of way.)
>Jack Sarfatti asks:
> What happens if we ... go to [the] category semi-Group - will the
> corresponding Hom(x,y) now be an "object"?
>No, but if we enrich the structure instead of impoverishing it, and go
>the category Abelian-Group, then Hom(X,Y) *is* an object.
This is reminiscent of the charming fact that a group object in the
category of groups is precisely an abelian group.
Let me explain.... a group is a set G with operations multiplication
m: G x G -> G, inverse inv: G -> G, and identity id: 1 -> G (where 1 is
your favorite one-element set) satisfying various axioms. Here I have
written the identity as a function rather than an "element of G" so that
we can say: G is an object in Set (i.e., a set), m, inv and id are
morphisms in Set (i.e., functions), and various laws hold
(associativity, etc.) which can all be expressed as commutative diagrams
in Set.
Now we can "relativize" the definition of a group if we replace the
category Set by some other category C. We then have the notion of a
"group object in C". That is, groups are sets with certain "extra
abilities", and group objects in C are objects in C with utterly
analogous "extra abilities". For this to work, the category C needs
an analog of the "x" that appears in the above paragraph, and also an
analog of the "1". This is precisely what "monoidal categories" are all
about. A monoidal category has a product "x" and a unit object "1"
satisfying various obvious axioms.... so we can talk about a group
object in any monoidal category C.
For example, a group object in Top, the category of topological spaces,
is just a topological group.
Similarly, a group object in Diff, the category of smooth manifolds, is
just a Lie group.
Now, what's a group object in Group, the category of groups??????
I'm sure you all appreciate the marvelous recursive/self-referential
quality of this little puzzle.
If one works it out, one sees that what it really amounts to is, "for
what groups G are the operations m: G x G -> G, inv: G -> G, and
id: 1 -> G *homomorphisms* rather than merely functions". For, after
all, the morphisms in Group are homomorphisms.
And then, with a wee bit of calculation, one sees that these groups are
precisely the Abelian (commutative) groups.
Now say one decides to keep playing this self-referential game, and ask,
what's a group object in Ab, the category of Abelian groups?
Perhaps something still cooler?
No..... actually not; I leave it to folks to check that an group
object in Ab is again just an Abelian group, i.e., EVERY object in Ab is
a group object.
I.e., this self-referential tower seems to have stabilized. This is
closely related to a big program that Jim Dolan and I are working on.
One could also try asking a different question: what's an *Abelian*
group object in Ab?
Well, first one has to figure out what the definition of an Abelian
group object in a category is. An abelian group, in terms of
diagrams, is just a group with the extra property that
G x G ---switch---> G x G
\ /
\ /
\ /
\ /
m\ /m
\ /
\ /
V V
G
(Hmm, for some reason they didn't equip ASCII with a good commutative
diagram package.) In other words, gh = hg, so if you "switch" and
multiply it's the same as multiplying.
Now, for this to make sense in a category we need to have a notion of
"switching". Such a category is called a braided monoidal category.
Its not so hard to see that Ab is a braided monoidal category in an
obvious sort of way, and an Abelian group object in Ab is just an
Abelian group. So even this slightly more subtle self-referential
property has "stabilized".
Now, I am too lazy now to figure out exactly what this has to do with
the fact that Ab is closed, i.e., that for any Abelian groups x and y,
Hom(x,y) is again an abelian group. But it seems sort of interesting.
Homework: what's a category object in Cat? What's a category object in
the category of THOSE things?
Michael Kagalenko
Hans Moravec <h...@cs.cmu.edu> wrote:
]
]>]Michael Kagalenko writes:
]>
]> I don't understand what you are saying here. In my understanding
]> of Copenhagen interpretation observer is not subject to interference
]> by definition; if something is subject to interference, it is part
]> of the system.
]
]That's where Everett beats Bohr, Occam-wise. Unlike Copenhagen, MW
]does not introduce, as a basic concept, the unnecessary idea of an
]observer, who, unlike everything else, is not described by a
]superposable wave function.
Well, instead of that, MWI introduces the unnecessary idea of
two classes of observations - ones that split wave function, and
ones that don't.
]
]Stop multiplying concepts needlessly!
]
]Many worlds : few concepts !
I think that you are not being careful while counting your concepts :-)