Tech building
Christina.Robertson
I'm an engineer (software), there is nothing that bugs me more than
wrong science in Sci Fi novels. However, I don't have a clue where to
start on my own tech research. I've finally found a story/characters
that seem to demand I write about them. This is good, usually my
interest in an idea withers and dies very quickly.
This time the story grew out of a character who I became facinated
with, then her interactions with another character became equally
facinating. Pretty soon that other character had become a person of
his own, quite capable of keeping my interest. The story grew and
evolved around these two characters. To some extent the world/universe
they inhabit also grew up around them, or at least so far has mainly
been revealed through my explorations of their characters.
And now comes time to start thinking about such basic things as how
these characters travel around their world. Interstellar travel is
required. Interstellar travel that takes less than generations is
required. And yet I'm left scratching my head where to start. I
need ships, I need engines, I need science. And I need it to be
believable enough for my own, rather critical, brain.
Where/how do you start your tech building? Little stuff (like computer
concepts, weapons, etc) I can handle but I've got zero background in
the science of moving a ship from one place to another. Wormholes,
hyperdrive, lightspeed, the possibilities seem endless. So where do
YOU start?
Chris
Jeff Stehman
Christina...@gmail.com says...
> Where/how do you start your tech building?
Stephen Hawking's _A Brief History of Time_. The chapter on wormholes
and time travel might help you rule out some things.
--Jeff Stehman
Dan Goodman
I suggest also asking on rec.arts.sf.science.
--
Dan Goodman
All political parties die at last of swallowing their own lies.
John Arbuthnot (1667-1735), Scottish writer, physician.
Journal http://dsgood.livejournal.com
Links http://del.icio.us/dsgood
Blog http://dsgood.googlepages.com
Michelle Bottorff
> And now comes time to start thinking about such basic things as how
> these characters travel around their world. Interstellar travel is
> required. Interstellar travel that takes less than generations is
> required. And yet I'm left scratching my head where to start. I
> need ships, I need engines, I need science. And I need it to be
> believable enough for my own, rather critical, brain.
>
> Where/how do you start your tech building? Little stuff (like computer
> concepts, weapons, etc) I can handle but I've got zero background in
> the science of moving a ship from one place to another. Wormholes,
> hyperdrive, lightspeed, the possibilities seem endless. So where do
> YOU start?
I start with the feel that I want, and I use the established handwaved
FTL system that best gives me that feel, and then once I have that FTL
system, I tend to work out from there, trying to be as realistic as my
story will allow.
For the Cultivator Universe I needed to do a lot of planet hopping, and
wanted fast, inexpensive, individual travel -- spaceships as cars. So
I decided that interplanetary travel would be accomplished using
portable wormholes.
For the Black Flag stuff, where the characters who inspired me happened
to be space pirates, I needed something very different -- spaceships as
ocean-liners. So I'm using the concept of a hyperspace, or subspace,
or whatever you want to call it for that universe. :)
--
Michelle Bottorff -> Chelle B. -> Shelby
L. Shelby, Writer http://www.lshelby.com/
Livejournal http://lavenderbard.livejournal.com/
rec.arts.sf.composition FAQ http://www.lshelby.com/rasfcFAQ.html
Gerry Quinn
> And now comes time to start thinking about such basic things as how
> these characters travel around their world. Interstellar travel is
> required. Interstellar travel that takes less than generations is
> required. And yet I'm left scratching my head where to start. I
> need ships, I need engines, I need science. And I need it to be
> believable enough for my own, rather critical, brain.
>
> Where/how do you start your tech building? Little stuff (like computer
> concepts, weapons, etc) I can handle but I've got zero background in
> the science of moving a ship from one place to another. Wormholes,
> hyperdrive, lightspeed, the possibilities seem endless. So where do
> YOU start?
Unless you really want to invent a new FTL tech, I'd suggest just using
something relatively generic and unexplained that suits your story.
For example, a ship that's in a region of fairly constant gravitational
potential (i.e. far from a planet or star) can jump to another such
region, in a short time or instantaneously. Just explain the
conditions of use, fuel cost, special rare elements needed, etc. -
whatever is relevant to the plot.
It probably can't be done with real physics, so in SF you get a pass.
- Gerry Quinn
Joel Crum
Short answer: I'd do some reading on the internet.
Long answer: FTL travel is probably impossible. So the first thing I'd
do is find an internet primer on why this is so. (Here's an
interesting one:
http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html
and here's NASA's take on it
http://www.nasa.gov/centers/glenn/research/warp/warpstat.html) Once
you're understand the problem you can start matching up various SF
tricks for FTL travel to the bit of real physics they're getting
around.
Wormholes, for example, don't require anything to go faster then light
because they cause two non-continuous bits of space to touch. The
problem is they can't be affected by anything other then gravity so you
can't move them around, and they are really tiny in the real world.
A "warp" drive is probably a spatial warp. So instead of accelerating
by throwing mass away from you, you'd be sliding into a portable
gravity well. Gravity *can* move people faster then light; that's why
black holes are postulated to exist. The problem is we can't generate
gravity as such.
"Subspace" and whatnot conjecture putting your ship in a place that
corresponds to the real world in a one-to-one way but that simply isn't
as big. Then you'd move (presumably in accord with all the
conventional laws) some distance in that place, and reenter in the real
world vastly far from where you started. The problem is we don't know
if such space exists (certain forms of string theory postulate it) and
we wouldn't know how to get there if it did.
And so forth.
You can do a credible hand wave over any of these (and a hand wave is
all it will ever be unless you're going to invent a real functional
starship before you write your story) so I'd second Michelle Bottorff
advice and pick the one that best suits your intended plotline. For
example, with as real-as-possible-wormholes (
http://www.nasa.gov/centers/glenn/research/warp/ideachev.html ) FTL
travel would be like taking a train. You'd go to the preexisting
wormhole by conventional means, step through to the other end, and then
go on to your destination by conventional means. Interstellar war
would probably be impossible via wormhole because it would be like
trying to invade Brittan via the chunnel, and it would probably take
more then a generation to build a wormhole bridge because you'd have
to move one of its ends through conventional space. You said you
wanted engines - so wormholes probably aren't for you.
- Joel C.
Logan Kearsley
news:1158157481....@e3g2000cwe.googlegroups.com...
> Discussion/question.
>
> And now comes time to start thinking about such basic things as how
> these characters travel around their world. Interstellar travel is
> required. Interstellar travel that takes less than generations is
> required. And yet I'm left scratching my head where to start. I
> need ships, I need engines, I need science. And I need it to be
> believable enough for my own, rather critical, brain.
For interstellar travel stuff, ask on rec.arts.sf.science. I'm not entirely
sure you'll like what you find, but it's a wonderful resource.
> Where/how do you start your tech building? Little stuff (like computer
> concepts, weapons, etc) I can handle but I've got zero background in
> the science of moving a ship from one place to another. Wormholes,
> hyperdrive, lightspeed, the possibilities seem endless. So where do
> YOU start?
In general? I have no idea. I just rummage about in my brain for something I
actually know already, or else something I think I heard about sometime that
sounds reasonable, and then hit Google and Wikipedia to start filling in the
necessary details.
But if you're truly stuck, as long as you at least know what sort of
question you want answered, the denizens rec.arts.sf.science are usually
very helpful. I suggest browsing the Google archives. There are lots of neat
interstellar travel concepts to be found there.
-l.
------------------------------------
My inbox is a sacred shrine, none shall enter that are not worthy.
Logan Kearsley
news:1158184832.8...@e63g2000cwd.googlegroups.com...
> > What would YOU do?
>
> Short answer: I'd do some reading on the internet.
>
> Long answer: FTL travel is probably impossible. So the first thing I'd
> do is find an internet primer on why this is so. (Here's an
> interesting one:
> http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html
> and here's NASA's take on it
> http://www.nasa.gov/centers/glenn/research/warp/warpstat.html) Once
> you're understand the problem you can start matching up various SF
> tricks for FTL travel to the bit of real physics they're getting
> around.
>
> Wormholes, for example, don't require anything to go faster then light
> because they cause two non-continuous bits of space to touch. The
> problem is they can't be affected by anything other then gravity so you
> can't move them around, and they are really tiny in the real world.
>
> A "warp" drive is probably a spatial warp. So instead of accelerating
> by throwing mass away from you, you'd be sliding into a portable
> gravity well. Gravity *can* move people faster then light; that's why
> black holes are postulated to exist. The problem is we can't generate
> gravity as such.
Gravity *can't* move things faster than light through space- but space
itself can move/expand/contract faster than light. Alcubierre-style drives
isolate a blob of space with your ship inside of it, and move it to some
other part of the universe arbitrarily quickly. The ship never actually
accelerates through space, so no FTL problem.
> "Subspace" and whatnot conjecture putting your ship in a place that
> corresponds to the real world in a one-to-one way but that simply isn't
> as big. Then you'd move (presumably in accord with all the
> conventional laws) some distance in that place, and reenter in the real
> world vastly far from where you started. The problem is we don't know
> if such space exists (certain forms of string theory postulate it) and
> we wouldn't know how to get there if it did.
Or, rather than being smaller, another version of subspace might have a
higher speed of light. This version has actually been seriously proposed by
folks working on Heim theory. How seriously one should take the people doing
the proposing is open to debate.
> You can do a credible hand wave over any of these (and a hand wave is
> all it will ever be unless you're going to invent a real functional
> starship before you write your story) so I'd second Michelle Bottorff
> advice and pick the one that best suits your intended plotline. For
> example, with as real-as-possible-wormholes (
> http://www.nasa.gov/centers/glenn/research/warp/ideachev.html ) FTL
> travel would be like taking a train. You'd go to the preexisting
> wormhole by conventional means, step through to the other end, and then
> go on to your destination by conventional means. Interstellar war
> would probably be impossible via wormhole because it would be like
> trying to invade Brittan via the chunnel, and it would probably take
> more then a generation to build a wormhole bridge because you'd have
> to move one of its ends through conventional space. You said you
> wanted engines - so wormholes probably aren't for you.
Unless you can generate a wormhole with the ends already in convenient
places, or somehow locate and inflate a convenient natural one.
Not meaning to be contrarian or anything, just pointing out the vastness of
the field of options.
James Nicoll
Logan Kearsley <chrono...@verizon.net> wrote:
>
>Or, rather than being smaller, another version of subspace might have a
>higher speed of light. This version has actually been seriously proposed by
>folks working on Heim theory. How seriously one should take the people doing
>the proposing is open to debate.
>
I'm sure it's nonsense but it has amusing consequences. For one
thing, post-stellar objects become valuable territory.
To make it more amusing, have the temperature of subspace be
inversely related to it's size.
--
http://www.cic.gc.ca/english/immigrate/
http://www.livejournal.com/users/james_nicoll
http://www.cafepress.com/jdnicoll (For all your "The problem with
defending the English language [...]" T-shirt, cup and tote-bag needs)
Logan Kearsley
news:eeagng$eis$1...@reader1.panix.com...
> In article <0X%Ng.18417$c22.12663@trnddc07>,
> Logan Kearsley <chrono...@verizon.net> wrote:
> >
> >Or, rather than being smaller, another version of subspace might have a
> >higher speed of light. This version has actually been seriously proposed
by
> >folks working on Heim theory. How seriously one should take the people
doing
> >the proposing is open to debate.
> >
>
> I'm sure it's nonsense but it has amusing consequences. For one
> thing, post-stellar objects become valuable territory.
Hm? Why is that?
I can think of a couple of possibilities, but they all seem rather dubious
and silly.
> To make it more amusing, have the temperature of subspace be
> inversely related to it's size.
An idea which actually makes good sense.
Hm. Maybe that's why the background always glowed red in Babylon 5
hyperspace scenes- the cosmic background radiation was warm enough to see.
Ben Crowell
right in my stories. However, I recently did a story where the plot
really required what I would call "silly science." IMO, it's the best
thing I've ever written :-) Look, readers will forgive you for writing
fantasy, if it's a really good story. They don't care that magic isn't
real. Readers will forgive you for writing a story like Jurgen, or
Little Red Riding Hood, where you don't even pretend to be depicting
psychological reality. They'll forgive anything, if the story is good.
If you know a ridiculous amount about 19th-century
firearms, and decide to fudge about the properties of a particular
revolver for plot purposes, nobody's going to know or care. The
danger is actually that you'll use too *much* of your knowledge of
19th-century firearms. You just don't want to fudge from a position
of ignorance.
If I write a story about a character named Sam Chrzanowski, who lives
on Edwards Street in New Haven, CT, my reader is not going to
go to the New Haven phone book, check for the name, and get upset
because Sam Chrzanowski isn't in it. If my reader happens to be
familiar with New Haven, he's just going to be impressed that
I did careful enough research to use the name of a real street.
I learned a heck of a lot of physics, as a kid, from reading science
fiction. At the time I was reading it, I pretty much knew when I
was finding out about real science, and when I wasn't. Warp drive:
fake. People on the moon have normal inertia but low weight: real.
It's like Little Red Riding Hood: it's not like we're damaging little
kids' knowledge of biology by making them think wolves can talk.
David Friedman
Ben Crowell <"crowell06 at lightSPAMandISmatterEVIL.com"> wrote:
> If you know a ridiculous amount about 19th-century
> firearms, and decide to fudge about the properties of a particular
> revolver for plot purposes, nobody's going to know or care.
Yes.
I learned what I could about trebuchets. I worked out on internal
evidence the distance between a trebuchet and a bridge it was throwing
rocks at. I concluded that the distance was at least fifty yards greater
than the range of an actual trebuchet.
I then ignored that conclusion and wrote the scene anyway. I doubt
anyone has noticed or will notice, other than those who have seen me
mention it.
--
http://www.daviddfriedman.com/ http://daviddfriedman.blogspot.com/
Author of _Harald_, a fantasy without magic.
Published by Baen, in bookstores now
Julian Flood
> You can do a credible hand wave over any of these (and a hand wave is
> all it will ever be unless you're going to invent a real functional
> starship before you write your story)
An interesting take is making use of realistic tech: the restrictions
can lead to interesting plot lines. In /Children of a Greater God/ (the
short it grew from is on my website) I solved the problem three ways and
found that I was really writing about people running away from death.
It's like restricting the rules of magic in fantasy, too much power and
it turns into a turkey shoot, get it right and the story turns into
something quite different.
JF
The real cause of global warming is at www.floodsclimbers.co.uk,
together with Life, The Universe and Climbing Plants.
Christina.Robertson
Joel Crum wrote:
<snip>
>Interstellar war
> would probably be impossible via wormhole because it would be like
> trying to invade Brittan via the chunnel, and it would probably take
> more then a generation to build a wormhole bridge because you'd have
> to move one of its ends through conventional space. You said you
> wanted engines - so wormholes probably aren't for you.
Definately counts out wormholes then. Part of the story requires
interstellar war. It DOES require that travel be difficult enough to
make war a rather bothersome undertaking, but not so bothersome that it
can't happen. Sort of a bottle neck that can be overcome with a bit of
time.
Thanks for hte links. :)
Chris
Christina.Robertson
Logan Kearsley wrote:
> An idea which actually makes good sense.
> Hm. Maybe that's why the background always glowed red in Babylon 5
> hyperspace scenes- the cosmic background radiation was warm enough to see.
I thought it just did that to give the Shadows a cool backdrop. ;)
Actually though a system along the lines of what is used in Babylon 5
is probably closest to what I'm looking for at this point.
Christina.Robertson
Julian Flood wrote:
> An interesting take is making use of realistic tech: the restrictions
> can lead to interesting plot lines. In /Children of a Greater God/ (the
> short it grew from is on my website) I solved the problem three ways and
> found that I was really writing about people running away from death.
> It's like restricting the rules of magic in fantasy, too much power and
> it turns into a turkey shoot, get it right and the story turns into
> something quite different.
Good point and two seperate solutions are probably needed in my story
as well. There are two distinct groups who need to have solved the
problem seperately from one another. They have very different
mindsets, and attitudes. One group would happily take a riskier form
of travel if it gets them there faster. The other group would do
everything they could to reduce risk and would happily take hundreds of
years to get somewhere if it would be safer than a method taking weeks
or days.
Chris
Christina.Robertson
> I'm a physicist, and generally pride myself on getting the science
> right in my stories. However, I recently did a story where the plot
> really required what I would call "silly science." IMO, it's the best
> thing I've ever written :-) Look, readers will forgive you for writing
> fantasy, if it's a really good story. They don't care that magic isn't
> real. Readers will forgive you for writing a story like Jurgen, or
> Little Red Riding Hood, where you don't even pretend to be depicting
> psychological reality. They'll forgive anything, if the story is good.
This is true, and a good point. I'm not worried about sticking to just
"we can prove it works NOW" science. That's annoying and simply won't
work for the story. What I don't want is to end up with a mode of
travel that simply screams at the reader's logic. I read a trillogy a
few years ago where travel was dealt with using wormholes and time
travel. On the surface the concept looked good, however it didn't WORK
logically. As soon as I, as a reader, started trying to hang the plot
points on some logical hooks it broke down. It quickly became very
obvious that the travel technology had been created and its rules set
out JUST so a particular plot would work. Unfortunately there were
large and obvious holes in its works and seriously detracted from the
story.
Mainly I just want to avoid that sort of problem. I have a feeling
choosing one of the "old faithful" travel methods will probably make
this unlikely as the tech will become rather invisible to a regular sf
reader.
Chris
Jonathan L Cunningham
> "James Nicoll" <jdni...@panix.com> wrote in message
> news:eeagng$eis$1...@reader1.panix.com...
> > In article <0X%Ng.18417$c22.12663@trnddc07>,
> > Logan Kearsley <chrono...@verizon.net> wrote:
> > >
> > >Or, rather than being smaller, another version of subspace might have a
> > >higher speed of light. This version has actually been seriously proposed
> by
> > >folks working on Heim theory. How seriously one should take the people
> doing
> > >the proposing is open to debate.
> > >
> >
> > I'm sure it's nonsense but it has amusing consequences. For one
> > thing, post-stellar objects become valuable territory.
>
> Hm? Why is that?
> I can think of a couple of possibilities, but they all seem rather dubious
> and silly.
AFAIK, for none of the "subspace" or "hyperspace" ideas could you get a
one-to-one correspondence with the real universe, unless the speed of
light was exactly the same, because the "shape" of the space would
be different, i.e. you'd have to set up a different one-to-one
correspondence for every frame of reference, or else postulate some
sort of absolute frame of reference (i.e. the same kind of thing you
need to get around time travel paradoxes, but for a different reason).
But I don't know of any objection to a hyperspace which is just extra
dimensions. (These extra dimensions would almost certainly not be the
extra dimensions needed for string theory etc.) But if particle physics
can postulate extra dimensions, I don't see why an SF writer shouldn't
postulate a few more. Then you can crumple up our universe like a
used tissue (in those extra dimensions) and all sorts of unpredictable
shortcuts through hyperspace become feasible.
That's my preferred approach: I don't really see the need for wormholes
as well. Weber uses them for instantaneous transport, and "ordinary"
hyperspace for slower (weeks long) travel. But really, there's no
reason to suppose that a wormhole, if it existed at all, would even be
a shortcut, let alone instantaneous![*]
For a 2D analogy: get a map of the world (or a globe made of something
very soft and scrunchy). Crumple it all up. Now, the "hyperspace"
distance between, say, New York and Paris is the actual distance (in
the real world) between those two places on the scrunched up map. Is it
long or short?
Now to construct a wormhole. Get a piece of tape ten yards long. Attach
one end to New York, the other to Paris. That's your wormhole. Unless
you started with a *very* big map, I expect the wormhole route is even
longer than the "realspace" route along the surface of the map, which
is certainly not shorter than the "hyperspace" route.
I hope y'all can visualise all that.
As for the original questioner: my advice would be to stick with what
you know (i.e. avoid things that would bother you as a reader) and write
the story. There are *lots* of popular science type references (some
specifically for SF writers) but you don't really need them except for
your *own* satisfaction. And if they're not the kind of stuff you read
for fun, there's not much point. There's too many to list.
If something specific comes up, by all means ask a more specific
question -- r.a.sf.science might be more suitable for some of them, but
to be honest, I don't think *for writing* SF you need to go there: you
just might get a better pointer to useful resources by asking here
first. We can always refer you to r.a.sf.science if it starts getting
too technical for this group. Which, for writing purposes, it needn't.
But it's a useful group if you want to check some particular deep
technical point or obscure scientific fact. They're very keen on
explosions, and space warfare, too.
Final thought: the most popular SF gets the science mostly wrong. Even
the ultra-hard SF which tries to get it all right gets things wrong.
Even textbooks get things wrong! :-) (And/or it goes out of date.)
Jonathan
[*] There's at least one SF short, where, when they finally invent a
hyperdrive, it turns out that the speed of light is *slower* in
hyperspace, and quite useless for space travel :-).
James Nicoll
Logan Kearsley <chrono...@verizon.net> wrote:
>"James Nicoll" <jdni...@panix.com> wrote in message
>news:eeagng$eis$1...@reader1.panix.com...
>> In article <0X%Ng.18417$c22.12663@trnddc07>,
>> Logan Kearsley <chrono...@verizon.net> wrote:
>> >
>> >Or, rather than being smaller, another version of subspace might have a
>> >higher speed of light. This version has actually been seriously proposed
>by
>> >folks working on Heim theory. How seriously one should take the people
>doing
>> >the proposing is open to debate.
>> >
>>
>> I'm sure it's nonsense but it has amusing consequences. For one
>> thing, post-stellar objects become valuable territory.
>
>Hm? Why is that?
>I can think of a couple of possibilities, but they all seem rather dubious
>and silly.
>
on your speed in normal space, times a multiplier of about 15,000. One way
to squeeze a little more speed out of a given rocket is to do a close fly-
by of some massive object and do a burn while you are close. This will
get you up to the escape velocity at closet approach.
John Schilling did point out that it's a good idea to keep
in mind how quickly periapsis goes by, which may limit the usefulness
of this move wrt cargos that can go sploosh.
Gruff
> For a 2D analogy: get a map of the world (or a globe made of something
> very soft and scrunchy). Crumple it all up. Now, the "hyperspace"
> distance between, say, New York and Paris is the actual distance (in
> the real world) between those two places on the scrunched up map. Is it
> long or short?
Nice analogy.
>
> Now to construct a wormhole. Get a piece of tape ten yards long. Attach
> one end to New York, the other to Paris. That's your wormhole. Unless
> you started with a *very* big map, I expect the wormhole route is even
> longer than the "realspace" route along the surface of the map, which
> is certainly not shorter than the "hyperspace" route.
>
Don't get this bit. A wormhole would be a little tiny connection
between two adjacent bit of paper and therefore would be the *same* as
your hyperspace distance - the only consideration being whether you
could travel in that direction without using the wormhole as the medium.
So to get from New York to Paris you might have to take several little
wormhole hops, or you get your hyperdrive to go the same route. A
little bit like taking the metro versus flying directly there, but all
in the hyperdimension. I'm not clear why you think the wormhole would
be ten yards long.
Gruff
--
http://www.gruffiti.com - Gruff's box of Gruffiti
http://www.bitesizedlanguages.com - Language learning in little bites
Joel Crum
> > A "warp" drive is probably a spatial warp. So instead of accelerating
> > by throwing mass away from you, you'd be sliding into a portable
> > gravity well. Gravity *can* move people faster then light; that's why
> > black holes are postulated to exist. The problem is we can't generate
> > gravity as such.
>
> Gravity *can't* move things faster than light through space- but space
> itself can move/expand/contract faster than light. Alcubierre-style drives
> isolate a blob of space with your ship inside of it, and move it to some
> other part of the universe arbitrarily quickly. The ship never actually
> accelerates through space, so no FTL problem.
I did a bit more reading and ran across Alcubierre's "Warp Drive".
If she wants the most real physics with ships and engines that's what
I'd go with.
I could be way out in left field here; I'm working without
references. But, as I recall, special relativity says that as you
approach the speed of light your mass increases (mass dilation) thus it
takes more energy to accelerate you. At light speed your mass, and the
energy required to accelerate you, are both infinite thus you can never
reach the speed of light. However, gravity accelerates all masses
equally so a gravitational accelerator shouldn't care how heavy you
get. I thought that's why black holes were postulated to exist in
the first place: their acceleration is so high that at some point
before you reach the surface you'd be going faster then light and
obviously nothing can return from beyond that point.
This lead me to think of a fictional FTL drive like the KK drives Alen
Dean Foster uses for his Flix series. Oh, cool, he has a page on them:
www.alandeanfoster.com/version2.0/kktech.htm . Anyway all this real
physics is pretty OT.
> > "Subspace" and whatnot conjecture putting your ship in a place that
> > corresponds to the real world in a one-to-one way but that simply isn't
> > as big. Then you'd move (presumably in accord with all the
> > conventional laws) some distance in that place, and reenter in the real
> > world vastly far from where you started. The problem is we don't know
> > if such space exists (certain forms of string theory postulate it) and
> > we wouldn't know how to get there if it did.
>
> Or, rather than being smaller, another version of subspace might have a
> higher speed of light. This version has actually been seriously proposed by
> folks working on Heim theory. How seriously one should take the people doing
> the proposing is open to debate.
João Magueijo, the guy who came up with VSL, rather seriously (well as
seriously as theoretical physicists ever get) proposed doing this in
our universe by flying along a super string - which is a place he
thinks light would travel much faster.
> > to move one of its ends through conventional space. You said you
> > wanted engines - so wormholes probably aren't for you.
>
> Unless you can generate a wormhole with the ends already in convenient
> places, or somehow locate and inflate a convenient natural one.
Yeah, I thought about that. But I figured in the context of what was
most reasonable one had best assume wormholes are pre-made tunnels.
> Not meaning to be contrarian or anything, just pointing out the vastness of
> the field of options.
>
> -l.
Oh it's a great debate! There's no way I'd rather waist time at work.
;-)
- Joel C.
ghostwriter
Weber solved that problem by having both systems exist in a single
universe, wormholes that ended in convenient places were highly prized
property since they allowed for instant travel with little or no fuel
used. Hyperdrive was used for traveling most of the time since good
stable wormholes were things found once every few centuries. Wormholes
allowed for mass transits and assault though one was possible but near
suicidal as the other side could set up stationary defense systems.
One of the major suprise attacks was the sending of a major battle
fleet the long way though hyperspace rather than using the suicide
stradegy. The result was months of being understrength for the chance
of catching an enemy completly by suprise.
Since multiple dimensions are posulated to exist, I always imagined a
energy intensive system that tunneled though one or more of the extra
dimensions, I dont know if that is subspace or hyperspace type system.
If space is curved it should be possible to drill a tunnel though space
and shorten the distance between two points. Assuming that the extra
dimension you are tunneling in is also curved you can continue though
the dimensions until have gone though enough dimensions that the
distance between two points in real space is near zero. At that point
portals and FTL become the same system.
Two stargates with MASSIVE power sources (think microwave power
harvested and beamed from a nearby sun or blackhole) could be used to
search for each other though the dimensions (think sonar pings being
sent and listened for thought all possible directions in a
multi-dimensional space), taking a long time and huge capital outlay,
with at least one needing to be physically moved to the endpoint. Once
the two mapped a zero distance course to each other the link could be
made semi-permanent. However once a new gate was in the system the
previously mapped routes though the other gates would allow it to dial
any other known gate. This process might take weeks, years, or decades
depending on the available computing power, curvature of the dimensions
between the two points as well as sheer luck at locating a "thin
place". Black holes might be prized real estate since the massive
gravity might create thinning in the first several dimensions and
therefore make the process faster.
FTL drive would be a ship that generated a tunnel, at the same time as
moving though it and listening/sending the sonar pulses. Since the
tunnel will collapse behind the ship a great deal less energy is
required to mantain the system and travel can be anywhere but traveling
faster would require you to go in higher and higher numbers of
dimensions thus requiring more power and increasing the chances of
getting into a region that curves unexpectantly and losing the ship. A
culture that used this system would have buoys that they navigated by,
placed all around their space, especially around odd curves, that would
send realtivly weak pulses that any ship could use to map the curvature
of the dimensions as they travelled. Think trimeres(sp), old
lighthouses, and the insane sailors that crewed them.
You then have two cultures a Gate Culture that would consider the ships
to be insanely dangerous, and a Ship Culture that would likley not have
the energy/computing power necessary to construct the gates, and might
consider them cowardly. A potential story point would be to have
someone realize that using a ship to transport a gate would not only
speed up the placement by years/decades but would also give the
computers a starting course to begin the calculations from speeding the
dialing process by years/decades. Also the bouy system could
potentially be used to give the gate computers an extremely detailed
starting map of the enemy territory and potentially allow for very fast
computing of the wormhole, assuming that access codes/compatiplity
issues could be resolved.
As far as combat goes the Gate Culture would likley have far more
advanced detection equipment and potential have more accurate targeting
system etc. They might also have a crude limited tunnel drive they use
on missles to give them FTL capability. The Ship Culture would likely
use a version of dive and slash where the ship micro-tunnels close in
to a target and releases a large amount of low quality missles then
micro tunnels out. The Gate Culture would have trouble dealing with the
density of fire since they would be used to small numbers of larger
tunneling missles, with missle counter fire also likely being in
multi-dimensional space. The Ship culture would have trouble since they
would not be able to approach in multi-dimensional space without being
detected and fired at while they are still tunneling, potentially
forcing a crash dive into more dimensions to avoid the weaker missle
drive with potentially disasterous effects.
Basically one society that uses a few advanced battleships and one that
uses many primitive submarines,
Good luck
Ghostwriter
nyra
>
> > > A "warp" drive is probably a spatial warp. So instead of accelerating
> > > by throwing mass away from you, you'd be sliding into a portable
> > > gravity well. Gravity *can* move people faster then light; that's why
> > > black holes are postulated to exist. The problem is we can't generate
> > > gravity as such.
> >
> > Gravity *can't* move things faster than light through space- but space
> > itself can move/expand/contract faster than light. Alcubierre-style drives
> > isolate a blob of space with your ship inside of it, and move it to some
> > other part of the universe arbitrarily quickly. The ship never actually
> > accelerates through space, so no FTL problem.
>
> I did a bit more reading and ran across Alcubierre's "Warp Drive".
> If she wants the most real physics with ships and engines that's what
> I'd go with.
>
> I could be way out in left field here; I'm working without
> references. But, as I recall, special relativity says that as you
> approach the speed of light your mass increases (mass dilation) thus it
> takes more energy to accelerate you. At light speed your mass, and the
> energy required to accelerate you, are both infinite thus you can never
> reach the speed of light. However, gravity accelerates all masses
> equally
Erm, does it really? I would think that things get different at
relativistic speeds.
> so a gravitational accelerator shouldn't care how heavy you
> get.
It should, because gravity is the force which pulls _two_ (or more)
masses together - the heavier the one, the stronger the pull on the
other. _Very_ close to the speed of light, a matchstick would be
heavier than the heaviest black hole - if it fell into a black hole,
the black hole would experience a bigger acceleration than the
matchstick.
> I thought that's why black holes were postulated to exist in
> the first place: their acceleration is so high that at some point
> before you reach the surface you'd be going faster then light and
> obviously nothing can return from beyond that point.
I thought that black holes have an _escape velocity_ which is higher
than the speed of light (which also prevents most electromagnetic rays
from getting out of it).
Anyway, if anything's to go faster than the speed of light in this
universe, you'll have to postulate that the relativistic equation
doesn't apply to it or that it has imaginary rest mass.
> Oh it's a great debate! There's no way I'd rather waist time at work.
Yeah, it's what the hip people love to do. Discuss astrophysics or
bust.
--
Se on Jumalan sana, sanoi mies,
kun akkansa raamatulla löi.
Logan Kearsley
news:1hlnob6.qs9b6hfpnqyrN%sp...@sofluc.co.uk.invalid...
>
> [*] There's at least one SF short, where, when they finally invent a
> hyperdrive, it turns out that the speed of light is *slower* in
> hyperspace, and quite useless for space travel :-).
Were the speed of light to be significantly slower in hyperspace, that would
make me just as happy as being significantly higher. The reason being, if
the speed of light is higher, you still have to expend oodles of energy to
accelerate to high speeds, but if the speed of light is slower, you can get
relativistic effects that reduce your subjective journey time with less
input of energy.
Logan Kearsley
> Joel Crum schrieb:
> >
> > I thought that's why black holes were postulated to exist in
> > the first place: their acceleration is so high that at some point
> > before you reach the surface you'd be going faster then light and
> > obviously nothing can return from beyond that point.
>
> I thought that black holes have an _escape velocity_ which is higher
> than the speed of light (which also prevents most electromagnetic rays
> from getting out of it).
It's partly that, and partly the time dilation effect. Obviously, you can
launch a rocket off of the Earth without starting it at escape velocity- you
just have to accelerate, adding more kinetic energy than gets converted to
potential by climbing, until you get going fast enough that you are going
faster than the *local* escape velocity, which won't be the same as on the
surface. But that won't work for launching from the 'surface' (event
horizon) of a blackhole, because time dilation makes it impossible for you
to accelerate from the point of view of an external observer.
Gruff
> Joel Crum schrieb:
>>>> A "warp" drive is probably a spatial warp. So instead of accelerating
>>>> by throwing mass away from you, you'd be sliding into a portable
>>>> gravity well. Gravity *can* move people faster then light; that's why
>>>> black holes are postulated to exist. The problem is we can't generate
>>>> gravity as such.
>>> Gravity *can't* move things faster than light through space- but space
>>> itself can move/expand/contract faster than light. Alcubierre-style drives
>>> isolate a blob of space with your ship inside of it, and move it to some
>>> other part of the universe arbitrarily quickly. The ship never actually
>>> accelerates through space, so no FTL problem.
>> I did a bit more reading and ran across Alcubierre's "Warp Drive".
>> If she wants the most real physics with ships and engines that's what
>> I'd go with.
>>
>> I could be way out in left field here; I'm working without
>> references. But, as I recall, special relativity says that as you
>> approach the speed of light your mass increases (mass dilation) thus it
>> takes more energy to accelerate you. At light speed your mass, and the
>> energy required to accelerate you, are both infinite thus you can never
>> reach the speed of light. However, gravity accelerates all masses
>> equally
>
> Erm, does it really? I would think that things get different at
> relativistic speeds.
Nyra's right I'm afraid. The observation Newton made about Earth's
gravity accelerating objects of similar mass equally is an extreme limit
approximation that fails under relativistic conditions. Not all masses
accelerate equally because their mutual gravity is different and motion
is relative. Unfortunately you can't really use Special Relativity to
predict what happens either as it doesn't account for acceleration at all.
Gruff
>>> A "warp" drive is probably a spatial warp. So instead of accelerating
>>> by throwing mass away from you, you'd be sliding into a portable
>>> gravity well. Gravity *can* move people faster then light; that's why
>>> black holes are postulated to exist. The problem is we can't generate
>>> gravity as such.
>> Gravity *can't* move things faster than light through space- but space
>> itself can move/expand/contract faster than light. Alcubierre-style drives
>> isolate a blob of space with your ship inside of it, and move it to some
>> other part of the universe arbitrarily quickly. The ship never actually
>> accelerates through space, so no FTL problem.
>
> I did a bit more reading and ran across Alcubierre's "Warp Drive".
> If she wants the most real physics with ships and engines that's what
> I'd go with.
>
> I could be way out in left field here; I'm working without
> references. But, as I recall, special relativity says that as you
> approach the speed of light your mass increases (mass dilation) thus it
It's not called mass dilation btw. You're thinking time dilation. It
doesn't have name really, people just refer to rest mass, invariant
mass, relativistic mass, etc.
Jonathan L Cunningham
> Jonathan L Cunningham wrote:
> > For a 2D analogy: get a map of the world (or a globe made of something
> > very soft and scrunchy). Crumple it all up. Now, the "hyperspace"
> > distance between, say, New York and Paris is the actual distance (in
> > the real world) between those two places on the scrunched up map. Is it
> > long or short?
>
> Nice analogy.
> >
> > Now to construct a wormhole. Get a piece of tape ten yards long. Attach
> > one end to New York, the other to Paris. That's your wormhole. Unless
> > you started with a *very* big map, I expect the wormhole route is even
> > longer than the "realspace" route along the surface of the map, which
> > is certainly not shorter than the "hyperspace" route.
> >
> Don't get this bit. A wormhole would be a little tiny connection
Why "little tiny"? Are you assuming it would be straight? Why?
> between two adjacent bit of paper and therefore would be the *same* as
> your hyperspace distance - the only consideration being whether you
> could travel in that direction without using the wormhole as the medium.
> So to get from New York to Paris you might have to take several little
> wormhole hops, or you get your hyperdrive to go the same route. A
> little bit like taking the metro versus flying directly there, but all
> in the hyperdimension. I'm not clear why you think the wormhole would
> be ten yards long.
Not that it *would* be ten yards long. But that it *could* be ten yards
long. If wormholes can exist at all, they are *extra* stuff. If you can
have an inch of "extra stuff", why can't you have a mile?
The significant difference between travelling in hyperspace and along
a wormhole is the difference between swimming a river and crossing a
bridge. If you are driving on a freeway, you can drive across a
bridge. Not many cars are capable of moving off the road system and
swimming across a river.
The idea of activating some sort of "wormhole drive" and "entering"
a wormhole is a nonsense[*]. It's mixing the two different ideas: of
entering hyperspace and entering a wormhole. Entering a wormhole (if
one existed) would be much like entering a tunnel. If you've ever
driven (in your car) into a tunnel, at what point did you activate
your car's "tunnel entry drive"?
OTOH, if you were driving your car, entering "hyperspace" would be
like taking off and flying: you are "entering" a third dimension (up).
Aircraft can do it, but cars can't.
I could go on, perhaps more clearly, but might have already sufficiently
answered your comment.
Jonathan
[*] A very common nonsense, in much very successful SF.
Jonathan L Cunningham
> "Jonathan L Cunningham" <sp...@sofluc.co.uk.invalid> wrote in message
> news:1hlnob6.qs9b6hfpnqyrN%sp...@sofluc.co.uk.invalid...
> >
> > [*] There's at least one SF short, where, when they finally invent a
> > hyperdrive, it turns out that the speed of light is *slower* in
> > hyperspace, and quite useless for space travel :-).
>
> Were the speed of light to be significantly slower in hyperspace, that would
> make me just as happy as being significantly higher. The reason being, if
> the speed of light is higher, you still have to expend oodles of energy to
> accelerate to high speeds, but if the speed of light is slower, you can get
> relativistic effects that reduce your subjective journey time with less
> input of energy.
Hmmm.
But, sadly, it couldn't be possible either.
To expand on what I said earlier:
Imagine we are here, and you are on a planet orbiting Sirius, 8 or so
light years away. The "distance" (interval) between us is undefined
unless we specify *when* we take the measurements. For a photon, which
travels at the speed photons travel at, this "distance" is exactly zero
and takes no time. That is, the "interval" between when it is sent
(the space and time coordinates) and when it arrives is mathematically
equal to zero. [And the photon experiences no time. Curious and a bit
boggling, but apparently true.]
In hyperspace, unless the speed of light exactly matches, the distance
will be non-zero: either timelike if the speed of light is greater, or
spacelike if less.[*]
So the two spaces are a different "shape" and can *not* be fitted
together. It's like (but worse) trying to draw an accurate map of the
globe on a flat sheet of paper. That analogy might suggest a fudge (I
just realised) which might let you handwave around the problem, but it's
not something I've previously thought about.
Jonathan
[*] Or t'other way about. I've had a little too much beer this evening
to think about it clearly enough to be sure.
Zeborah
> "Jonathan L Cunningham" <sp...@sofluc.co.uk.invalid> wrote in message
> news:1hlnob6.qs9b6hfpnqyrN%sp...@sofluc.co.uk.invalid...
> >
> > [*] There's at least one SF short, where, when they finally invent a
> > hyperdrive, it turns out that the speed of light is *slower* in
> > hyperspace, and quite useless for space travel :-).
>
> Were the speed of light to be significantly slower in hyperspace, that would
> make me just as happy as being significantly higher. The reason being, if
> the speed of light is higher, you still have to expend oodles of energy to
> accelerate to high speeds, but if the speed of light is slower, you can get
> relativistic effects that reduce your subjective journey time with less
> input of energy.
Oh! No, here's the thing: Einstein's equations, IIRC, don't prove that
it's impossible to go faster than light; rather that the closer you get
to the speed of light (from either direction) the more energy you have
to put in.
If I'm recalling that correctly, then, and given a universe where normal
space has speed of light c(n) and hyperspace has speed of light c(h),
then to get faster than light you need to:
a) in normal space, accelerate to a speed v such that c(h) < v < c(n)
b) switch into hyperspace. You're now going faster than the speed of
light, so it actually takes less energy to accelerate *faster* (ie
further from the speed of light).
c) accelerate as much as you like
d) at some point decelerate back to speed v (this will take more energy
than accelerating from it did, I think?), and switch back to normal
space so you're slower than the speed of light again and can decelerate
to a halt relative to your destination.
Zeborah
--
Gravity is no joke.
http://www.geocities.com/zeborahnz/
Monique Y. Mudama
> I'm a physicist, and generally pride myself on getting the science
> right in my stories. However, I recently did a story where the plot
> really required what I would call "silly science." IMO, it's the
> best thing I've ever written :-) Look, readers will forgive you for
> writing fantasy, if it's a really good story. They don't care that
> magic isn't real. Readers will forgive you for writing a story like
> Jurgen, or Little Red Riding Hood, where you don't even pretend to
> be depicting psychological reality. They'll forgive anything, if the
> story is good.
Agreed 100%. I would rather read a great story with some technical
silliness than great technical details with poor story. (Now, what
makes a great story? Um, it depends.)
> If you know a ridiculous amount about 19th-century firearms, and
> decide to fudge about the properties of a particular revolver for
> plot purposes, nobody's going to know or care. The danger is
> actually that you'll use too *much* of your knowledge of
> 19th-century firearms. You just don't want to fudge from a position
> of ignorance.
Agreed again, this time about the danger. I get so bored when an
author devotes paragraph after paragraph to establishing their
scientific chops. I don't care! Tell me about the people. Tell me
about their problems. Tell me about the ethical dilemma. If I've
been really good today, give me the ending that isn't at all what I
expected and makes me, in the words of Ani DiFranco, "makes me say,
you know, I've never heard it put that way -- makes me go, what did
you just say?"
I know that some readers do care about scientific plausibility, but I
don't. If anything, when someone starts justifying their tech, I
start feeling obligated to read it carefully and look for the holes.
But more likely, I groan and look for the next paragraph where
someone's talking.
--
monique
David Friedman
zeb...@gmail.com (Zeborah) wrote:
Unfortunately such a method still gets you into problems with causality,
since a positive spacelike four vector in one reference system is a
negative spacelike four vector in another.
Peter Knutsen (usenet)
> Unless you really want to invent a new FTL tech, I'd suggest just using
> something relatively generic and unexplained that suits your story.
Unexpained in the sense of why the tech can do FTL, but preferably not
unexplained in terms of when the tech can and cannot do FTL, and how
fast it can do it.
> For example, a ship that's in a region of fairly constant gravitational
> potential (i.e. far from a planet or star) can jump to another such
> region, in a short time or instantaneously. Just explain the
> conditions of use, fuel cost, special rare elements needed, etc. -
> whatever is relevant to the plot.
>
> It probably can't be done with real physics, so in SF you get a pass.
--
Peter Knutsen
sagatafl.org
Gruff
I'm not quite clear what you're trying to say here. Which distance?
> So the two spaces are a different "shape" and can *not* be fitted
> together.
*balk* er... mapping? There's nothing unreasonable about assuming that
universal constants can change with depth into hyperspace. There's
*also* no reason to assume they stay constant in our space, so even if
the universe is infinite (in which case your mapping statement could be
a problem) it could be resolved by local variation.
> It's like (but worse) trying to draw an accurate map of the
> globe on a flat sheet of paper. That analogy might suggest a fudge (I
> just realised) which might let you handwave around the problem, but it's
> not something I've previously thought about.
> Jonathan
> [*] Or t'other way about. I've had a little too much beer this evening
> to think about it clearly enough to be sure.
Gruff
Gruff
> Gruff <gruffsta...@googlemail.com> wrote:
>
>> Jonathan L Cunningham wrote:
>>> For a 2D analogy: get a map of the world (or a globe made of something
>>> very soft and scrunchy). Crumple it all up. Now, the "hyperspace"
>>> distance between, say, New York and Paris is the actual distance (in
>>> the real world) between those two places on the scrunched up map. Is it
>>> long or short?
>> Nice analogy.
>>> Now to construct a wormhole. Get a piece of tape ten yards long. Attach
>>> one end to New York, the other to Paris. That's your wormhole. Unless
>>> you started with a *very* big map, I expect the wormhole route is even
>>> longer than the "realspace" route along the surface of the map, which
>>> is certainly not shorter than the "hyperspace" route.
>>>
>> Don't get this bit. A wormhole would be a little tiny connection
>
> Why "little tiny"? Are you assuming it would be straight? Why?
Well, for a start (according to some theorists) they're likely to be
around the plank length in scale and would need expanding.
>> between two adjacent bit of paper and therefore would be the *same* as
>> your hyperspace distance - the only consideration being whether you
>> could travel in that direction without using the wormhole as the medium.
>> So to get from New York to Paris you might have to take several little
>> wormhole hops, or you get your hyperdrive to go the same route. A
>> little bit like taking the metro versus flying directly there, but all
>> in the hyperdimension. I'm not clear why you think the wormhole would
>> be ten yards long.
>
> Not that it *would* be ten yards long. But that it *could* be ten yards
> long. If wormholes can exist at all, they are *extra* stuff. If you can
> have an inch of "extra stuff", why can't you have a mile?
Sure... but you wouldn't use the long ones would you? You argument
implied there would *only* be long ones (or I misunderstood what you
were arguing). My point is that you would hunt for the short ones that
connect useful bits of space through one or several hyperdimensions.
>
> The significant difference between travelling in hyperspace and along
> a wormhole is the difference between swimming a river and crossing a
> bridge. If you are driving on a freeway, you can drive across a
> bridge. Not many cars are capable of moving off the road system and
> swimming across a river.
>
> The idea of activating some sort of "wormhole drive" and "entering"
> a wormhole is a nonsense[*]. It's mixing the two different ideas: of
> entering hyperspace and entering a wormhole. Entering a wormhole (if
> one existed) would be much like entering a tunnel. If you've ever
> driven (in your car) into a tunnel, at what point did you activate
> your car's "tunnel entry drive"?
Agreed, but actually I've never read about a wormhole drive (though I
don't doubt they're been written if you say so). However, given that
our wormholes are plank length in scale, you either need to seed them
with exotic matter to stretch them open, or have said "drive" to do so
on demand, to allow you to drive through. It's not an unreasonable
fiction given that the whole idea of wormholes is completely
hypothetical anyway.
> OTOH, if you were driving your car, entering "hyperspace" would be
> like taking off and flying: you are "entering" a third dimension (up).
You said this before, but which dimension do you think the wormholes are
going through?! They're orthogonal too*! It's not as if they're
travelling in the same dimensions as we are.
* Or rather they at least have to have an orthogonal element.
Gruff
> In article <1hlpo01.1cvpu6s18y7yliN%zeb...@gmail.com>,
> zeb...@gmail.com (Zeborah) wrote:
>
>> Logan Kearsley <chrono...@verizon.net> wrote:
>>
>>> "Jonathan L Cunningham" <sp...@sofluc.co.uk.invalid> wrote in message
>>> news:1hlnob6.qs9b6hfpnqyrN%sp...@sofluc.co.uk.invalid...
>>>> [*] There's at least one SF short, where, when they finally invent a
>>>> hyperdrive, it turns out that the speed of light is *slower* in
>>>> hyperspace, and quite useless for space travel :-).
>>> Were the speed of light to be significantly slower in hyperspace, that would
>>> make me just as happy as being significantly higher. The reason being, if
>>> the speed of light is higher, you still have to expend oodles of energy to
>>> accelerate to high speeds, but if the speed of light is slower, you can get
>>> relativistic effects that reduce your subjective journey time with less
>>> input of energy.
>> Oh! No, here's the thing: Einstein's equations, IIRC, don't prove that
>> it's impossible to go faster than light; rather that the closer you get
>> to the speed of light (from either direction) the more energy you have
>> to put in.
>>
>> If I'm recalling that correctly, then, and given a universe where normal
>> space has speed of light c(n) and hyperspace has speed of light c(h),
>> then to get faster than light you need to:
This is correct, however it's worth pointing out here that this is not
the same concept of hyperspace that Jonathan and I have been discussing
so there's a possible confusion of terms to be aware of. The hyperspace
you're referring to is a logical consequence of the Lorentz equations
which have a sort of mirror symmetry for the domain of velocities faster
than light speed. This "hyperspace" is the same space as ours but
different rules apply once objects start travelling at speeds >c.
Hypothetically, tachyons travel in this domain, and causally they appear
to us to be travelling backwards in time.
The hyperspace JL and I were discussing is a synonym for any set of
spatiotemporal dimensions orthogonal to the ones we perceive.
>> a) in normal space, accelerate to a speed v such that c(h) < v < c(n)
>> b) switch into hyperspace. You're now going faster than the speed of
>> light, so it actually takes less energy to accelerate *faster* (ie
>> further from the speed of light).
>> c) accelerate as much as you like
>> d) at some point decelerate back to speed v (this will take more energy
>> than accelerating from it did, I think?), and switch back to normal
>> space so you're slower than the speed of light again and can decelerate
>> to a halt relative to your destination.
>
> Unfortunately such a method still gets you into problems with causality,
> since a positive spacelike four vector in one reference system is a
> negative spacelike four vector in another.
>
Um... isn't that perfect for SF?!
;o)
Gruff
Scientist about an ex-aerospace engineer, Roger Shawyer, who claims to
have invented a device capable of exerting an external force without
explusion or contact. There are no moving parts and no fuel (other than
electricity). It's based on microwaves trapped in a waveguide and due
to some quirk of relativity, they can exert a force greater on one end
than the other, even though none of them escape.
At the moment we're only talking (in theory) about 88 millinewtons for
700 watts, but for space travel this is more than the SMART-1 ion drive
which currently exerts 70 mN for the same power.
He has at least one adamant oponent who describes it as "a load of
bloody rubbish" but lots of support too. A microwave engineer at
Imperial College described it as "outstanding science".
He claims to have a device built already which exerts 16mN using 1kW of
power but it's being independantly reviewed.
Shawyer believes it should be possible to create engines capable of
sufficient thrust to hover (just by powering the devices, no expulsion
of fuel, nothing) which is like something out of sci fi.
The barrier to success appears to be building non-lossy waveguides (with
a high 'Q' factor) but if his calculations are correct and he can build
small waveguides with Q of several billion (requiring high temp
superconductors) the device should be able to generate 30kN per kW,
enough to lift a large car.
Is the end of wings and wheels in sight?
Gerry Quinn
cru...@gmail.com says...
> I could be way out in left field here; I'm working without
> references. But, as I recall, special relativity says that as you
> approach the speed of light your mass increases (mass dilation) thus it
> takes more energy to accelerate you. At light speed your mass, and the
> energy required to accelerate you, are both infinite thus you can never
> reach the speed of light. However, gravity accelerates all masses
> equally so a gravitational accelerator shouldn't care how heavy you
> get. I thought that's why black holes were postulated to exist in
> the first place: their acceleration is so high that at some point
> before you reach the surface you'd be going faster then light and
> obviously nothing can return from beyond that point.
Usenet relativity FAQ:
< http://www2.corepower.com:8080/~relfaq/relativity.html >
..gives a good primer on special and general relativity.
Of course there are good reasons to doubt the plausibility of
Alcubierre warp drives etc. They tend to be based on ignoring
considerations from all physics other than general relativity. General
relativity conflicts with quantum mechanics, and the smart money is on
the latter winning the day - something's going to give in general
relativity, perhaps a lot more than its devoted students imagine.
But that's no reason to avoid them in SF, of course.
- Gerry Quinn
Gerry Quinn
dd...@daviddfriedman.nopsam.com says...
Causality isn't that big an issue - if FTL travel is discovered, we
just have to drop relativity in favour of a more old-fashioned ether-
like approach. It wouldn't turn physics on its head as much as you
might think.
The main problem would be explaining why particles aren't doing this
all the time. But if FTL (by any means) requires special techniques to
'unlock', this is probably acceptable.
- Gerry Quinn
Michelle Bottorff
> > If you know a ridiculous amount about 19th-century firearms, and
> > decide to fudge about the properties of a particular revolver for
> > plot purposes, nobody's going to know or care. The danger is
> > actually that you'll use too *much* of your knowledge of
> > 19th-century firearms. You just don't want to fudge from a position
> > of ignorance.
>
> Agreed again, this time about the danger. I get so bored when an
> author devotes paragraph after paragraph to establishing their
> scientific chops. I don't care! Tell me about the people.
I agree...
...But I would like to note that what is talked about here and what
actually gets into the book are two different things. :)
All the techy babbling I do in here is so that *I* know how it works,
because as an author, I need that. In contrast, I believe I don't tend
to talk about my characters much here. I don't think that means that I
write books that are all about science and nothing about character. (I
hope not considering that of the six novel mss I've written, only one is
sf, four are fantasy, and one was a regency romance.)
When Bambi picks up the damaged needler from the wreckage of the perps
ship, she checks it out, discovers that its has an unlisenced amunition
feed, and realizes that her opponents probably have deadly ordinance--
if you are going to have an illegal gun, you might as well get one that
can do some real damage, after all. I don't explain the science, or the
economics, or the legal situation behind that, because none of that
matters to *her*.
I had to know about the science and the economics and the legalities
myself, however, or I wouldn't have known that such a thing as an
unlisenced ammunition feed was possible.
--
Michelle Bottorff -> Chelle B. -> Shelby
L. Shelby, Writer http://www.lshelby.com/
Livejournal http://lavenderbard.livejournal.com/
rec.arts.sf.composition FAQ http://www.lshelby.com/rasfcFAQ.html
Christina.Robertson
Michelle Bottorff wrote:
> I agree...
> ...But I would like to note that what is talked about here and what
> actually gets into the book are two different things. :)
> I had to know about the science and the economics and the legalities
> myself, however, or I wouldn't have known that such a thing as an
> unlisenced ammunition feed was possible.
Exactly. I've got reams of background information. Government
structure, military ranks, culture, law, religion, etc. Most of it
will never actually end up in the story but its important (to me) to
understand my world that well. Same thing with the tech. In the book I
never discuss the engines, but a character might comment on how many
jumps are left till their destination or feel queasy because the sping
of the ship (to create artificial gravity) upsets her stomach. While
the reader isn't gonig to get a science primer understanding the tech
as well as I can makes it easier for the characters to have realistic
reactions and interactions with it. (And its really characters I care
about. They always come first for me and the plot develops as a way to
explore those characters.)
Chris
Ben Crowell
> All the techy babbling I do in here is so that *I* know how it works,
> because as an author, I need that. In contrast, I believe I don't tend
> to talk about my characters much here. I don't think that means that I
> write books that are all about science and nothing about character. (I
> hope not considering that of the six novel mss I've written, only one is
> sf, four are fantasy, and one was a regency romance.)
This reminds me of the standard advice given to aspiring young jazz
musicians: learn all your scales and arpeggios in all twelve keys,
and then forget about them and play music. In other words, if someone
in the audience is thinking, "That cat really knows his scales,"
you've failed.
Richard Kennaway
> Interestingly there is a fascinating article in this week's New
> Scientist about an ex-aerospace engineer, Roger Shawyer, who claims to
> have invented a device capable of exerting an external force without
> explusion or contact. There are no moving parts and no fuel (other than
> electricity). It's based on microwaves trapped in a waveguide and due
> to some quirk of relativity, they can exert a force greater on one end
> than the other, even though none of them escape.
There has been some discussion of this on rasf.science in the last week
or two.
> Is the end of wings and wheels in sight?
I wish, but "interesting if true" stories are usually neither
interesting nor true.
--
Richard Kennaway
Julian Flood
>"That cat really knows his scales,"
Please tell me it's true. Somewhere people still call cool dudes 'cats'.
No, David, not you.
JF
I've been on YouTube and found Johnny Cash's Hurt. Jacey, that's what I
do. The humanity of a dying man -- get that in your work and you're...
well, not laughing. On a roll, engaged. It stops a noisy pub in its tracks.
Logan Kearsley
news:1hlpo01.1cvpu6s18y7yliN%zeb...@gmail.com...
> Logan Kearsley <chrono...@verizon.net> wrote:
>
> > "Jonathan L Cunningham" <sp...@sofluc.co.uk.invalid> wrote in message
> > news:1hlnob6.qs9b6hfpnqyrN%sp...@sofluc.co.uk.invalid...
> > >
> > > [*] There's at least one SF short, where, when they finally invent a
> > > hyperdrive, it turns out that the speed of light is *slower* in
> > > hyperspace, and quite useless for space travel :-).
> >
> > Were the speed of light to be significantly slower in hyperspace, that
would
> > make me just as happy as being significantly higher. The reason being,
if
> > the speed of light is higher, you still have to expend oodles of energy
to
> > accelerate to high speeds, but if the speed of light is slower, you can
get
> > relativistic effects that reduce your subjective journey time with less
> > input of energy.
>
> Oh! No, here's the thing: Einstein's equations, IIRC, don't prove that
> it's impossible to go faster than light; rather that the closer you get
> to the speed of light (from either direction) the more energy you have
> to put in.
Well, it's true that solutions do exist for particles travelling faster than
light, they just tend to either not make a lot of sense, or make annoyingly
inconvenient sense. Imaginary numbers are involved.
> If I'm recalling that correctly, then, and given a universe where normal
> space has speed of light c(n) and hyperspace has speed of light c(h),
> then to get faster than light you need to:
>
> a) in normal space, accelerate to a speed v such that c(h) < v < c(n)
> b) switch into hyperspace. You're now going faster than the speed of
> light, so it actually takes less energy to accelerate *faster* (ie
> further from the speed of light).
Quite possibly, you would spontaneously emit energy in the form of Cerenkov
radiation, and thus continuously accelerate. But then, you might not.
> c) accelerate as much as you like
> d) at some point decelerate back to speed v (this will take more energy
> than accelerating from it did, I think?), and switch back to normal
> space so you're slower than the speed of light again and can decelerate
> to a halt relative to your destination.
All of that depends on a certain assumption about how hyperspace translation
works- that relative velocities between objects in hyperspace and normal
space are measured the same as if both objects were in the same space. I
would find it more plausible to assume that gamma factors remain constant in
hyperspace translations, so that your speed scales to the appropriate
fraction of c in whatever space you're in.
DougL
> > Oh! No, here's the thing: Einstein's equations, IIRC, don't prove that
> > it's impossible to go faster than light; rather that the closer you get
> > to the speed of light (from either direction) the more energy you have
> > to put in.
> >
> > If I'm recalling that correctly, then, and given a universe where normal
> > space has speed of light c(n) and hyperspace has speed of light c(h),
> > then to get faster than light you need to:
> >
> > a) in normal space, accelerate to a speed v such that c(h) < v < c(n)
> > b) switch into hyperspace. You're now going faster than the speed of
> > light, so it actually takes less energy to accelerate *faster* (ie
> > further from the speed of light).
> > c) accelerate as much as you like
> > d) at some point decelerate back to speed v (this will take more energy
> > than accelerating from it did, I think?), and switch back to normal
> > space so you're slower than the speed of light again and can decelerate
> > to a halt relative to your destination.
>
> Unfortunately such a method still gets you into problems with causality,
> since a positive spacelike four vector in one reference system is a
> negative spacelike four vector in another.
If there exist two universes with different speeds of light relative to
some mapping between the universes (aka you can go faster than the
speed of light in one by swapping to the other), and a mapping (with
reasonable properties) between space-time events in one universe to the
other, then the mapping itself defines a preferred frame of reference
in each universe.
Thus the existence of the mapping of four-space in our universe to
hyperspace can make it impossible to actually use such transfers to
travel backward in time.
The time-travel aspect of FTL is ENTIRELY an artifact of the presumed
ability of the traveler to somehow choose or change WHICH frame of
reference he is measuring his speed in, a preferred reference frame
eliminates most of the problems.
Relativity depends on (4) assumptions which can be phrased roughly as:
(1) The axioms of some fairly basic mathematics and the idea that you
can model reality with that mathematics (duh).
(2) There is a measurable speed that comes up in mathematically
describing physical law.
(3) There is no preferred frame of reference.
(4) There is no fundamental difference between acceleration due to
gravity and other forms of acceleration. (This is needed only for GR,
the prohibition on FTL is special relativity and doesn't need it.)
Of these if you want FTL the obvious one to attack is (3). 4 doesn't
matter to causality and FTL (the problems are all present in Special
Relativity), 1 and 2 are either true or the universe is MUCH stranger
than we can imagine.
But proving that there ISN'T a preferred frame of reference is an
absurdity, you can't prove a negative. If you want FTL just assume one,
take it as given.
DougL
Jonathan L Cunningham
> Jonathan L Cunningham wrote:
(snip)
> > In hyperspace, unless the speed of light exactly matches, the distance
> > will be non-zero: either timelike if the speed of light is greater, or
> > spacelike if less.[*]
>
> I'm not quite clear what you're trying to say here. Which distance?
>
> > So the two spaces are a different "shape" and can *not* be fitted
> > together.
>
> *balk* er... mapping? There's nothing unreasonable about assuming that
You can't map, say, a torus onto a sphere. They're different shapes.
Similarly, the only way hyperspace could be the same "shape" as our
universe, would be if the speed of light in hyperspace corresponded
exactly with the speed of light in our space.
> universal constants can change with depth into hyperspace. There's
> *also* no reason to assume they stay constant in our space, so even if
> the universe is infinite (in which case your mapping statement could be
> a problem) it could be resolved by local variation.
It's not a question of universal constants. The speed of light isn't
a constant because we say so. It's the speed which is the same for all
observers. The consequences of that were deduced by Einstein, and some
of those consequences implied something about the shape of space - the
way bits of space fit together.
So, in a hyperspace, if there is anything corresponding to the speed of
light, that will also determine the shape of the space. And if the speed
doesn't correspond to the speed in our universe, that space will have
a different shape. There won't be any way to fit them together that
works in more than one frame of reference.
If you assume a Newtonian universe, it's easy to imagine how hyperspace
might overlay the "normal" universe. But if you imagine a Newtonian
universe, you can travel faster than light anyway. As Logan (I think)
commented, it might still be useful to have hyperspace, to save all
that accelerating.
I suppose I'm saying that, if you could somehow travel into hyperspace,
it would be more like the kind of stories where it's unpredictable where
you'll come out, than the sort where hyperspace is some sort of
"overspace" which is "above" ours, with stars poking through all in
the same spatial relationship to each other that they have in normal
space.
Jonathan
P.S. I've just read one of your other posts. Yes, this discussion is in
danger of talking at cross-purposes if people start talking about
different *kinds* of hyperspace without realising it. Since there's no
evidence for *any* kind of hyperspace, that's a big risk. My original
comment was that one kind of hyperspace seemed ok to me, and that, IMHO,
some of the other kinds (often used in fiction) were geometrically
impossible, and assumed "Newtonian Physics with an arbitrary speed
limit". Whereas the speed limit in relativity is not arbitrary. It's
*the* speed limit. Changing it would require changing lots of other
things as well. (I.e. even if "universal constants" can change - an
interesting conjecture I'm inclined to go along with - they can't
change independently of each other.)
Jonathan L Cunningham
> Logan Kearsley <chrono...@verizon.net> wrote:
>
> > "Jonathan L Cunningham" <sp...@sofluc.co.uk.invalid> wrote in message
> > news:1hlnob6.qs9b6hfpnqyrN%sp...@sofluc.co.uk.invalid...
> > >
> > > [*] There's at least one SF short, where, when they finally invent a
> > > hyperdrive, it turns out that the speed of light is *slower* in
> > > hyperspace, and quite useless for space travel :-).
> >
> > Were the speed of light to be significantly slower in hyperspace, that would
> > make me just as happy as being significantly higher. The reason being, if
> > the speed of light is higher, you still have to expend oodles of energy to
> > accelerate to high speeds, but if the speed of light is slower, you can get
> > relativistic effects that reduce your subjective journey time with less
> > input of energy.
>
> Oh! No, here's the thing: Einstein's equations, IIRC, don't prove that
> it's impossible to go faster than light; rather that the closer you get
> to the speed of light (from either direction) the more energy you have
> to put in.
>
> If I'm recalling that correctly, then, and given a universe where normal
> space has speed of light c(n) and hyperspace has speed of light c(h),
> then to get faster than light you need to:
>
> a) in normal space, accelerate to a speed v such that c(h) < v < c(n)
> b) switch into hyperspace. You're now going faster than the speed of
> light, so it actually takes less energy to accelerate *faster* (ie
> further from the speed of light).
(snip)
That's what I was saying (in my discussion with Gruff) was impossible.
ISTM, from consideration of the geometry, that c(h) = c(n) of necessity,
or else that you don't have some universe-independent v, you have v(n)
and v(h), and that when you translate into hyperspace, your v(n) is
scaled in the same ratio, i.e. if v(n) = 0.8*c(n), then v(h) will be
0.8*c(h). (Or possibly something more complicated.)
Your (a) and (b) are easy to envisage in a Newtonian universe (with
a Newtonian hyperspace) where c(n) and c(h) are arbitrary limits imposed
by nature. But I cannot myself visualise it working in an Einsteinian
universe (i.e. one where space and time are not separate, and the
formula for distance is s*s = x*x + y*y + z*z - ct * ct).
I'm not convinced that everyone else is visualising this hyperspace
discussion with the correct geometry: Newtonian physics seems so much
more intuitive! :-)
This ties in with what I said at the beginning of the thread: from a
writing POV, unless your aim is to educate the reader, you (the OP)
might be better off writing what seems plausible to you: it will almost
certainly be even more plausible to your readers[*]!
Hmmm. I've just thought of a (weak) analogy. Imagine a teleport machine.
It violates conservation of angular momentum. Obvious? Imagine teleport
booths either side of a railway line. In the stationary frame, stuff
in one booth has no angular momentum before or after transport. But in
the frame of reference of a train which just happens to be passing,
the act of teleporting between booths converts anti-clockwise angular
momentum into clockwise. You *could* conserve angular momentum in
the train frame, by spinning the load. (Transport a cat: is there room
to spin a cat in your teleport booth?) But a spinning cat won't conserve
angular momentum in the stationary frame, or the frame of reference of a
train travelling at a different speed.
Teleport booths *always* violate conservation of angular momentum *in
all frames except one*. Don't let that stop you using them in stories.
(Niven wrote a whole series, in some of which he worried about
conservation of energy. I don't think he realised his transport booths
violate conservation of angular momentum.)
I sometimes wonder whether that's why things stay where they're put: to
conserve angular momentum. :-)
Jonathan
[*] Except me! :-) But if I can read David Weber, I can take almost
any kind of hyperspace and FTL travel :-)
Jonathan L Cunningham
> Jonathan L Cunningham wrote:
> > Gruff <gruffsta...@googlemail.com> wrote:
(snip)
> >>>
> >> Don't get this bit. A wormhole would be a little tiny connection
> >
> > Why "little tiny"? Are you assuming it would be straight? Why?
>
> Well, for a start (according to some theorists) they're likely to be
> around the plank length in scale and would need expanding.
I always assumed that referred to the diameter of the "throat" - not
the length of the wormhole. But I 'fess I'm not sure why I assume that.
> >> So to get from New York to Paris you might have to take several little
> >> wormhole hops, or you get your hyperdrive to go the same route. A
> >> little bit like taking the metro versus flying directly there, but all
> >> in the hyperdimension. I'm not clear why you think the wormhole would
> >> be ten yards long.
> >
> > Not that it *would* be ten yards long. But that it *could* be ten yards
> > long. If wormholes can exist at all, they are *extra* stuff. If you can
> > have an inch of "extra stuff", why can't you have a mile?
>
> Sure... but you wouldn't use the long ones would you? You argument
> implied there would *only* be long ones (or I misunderstood what you
I don't see why you got that. What I actually said was:
But really, there's no reason to suppose that a wormhole, if it
existed at all, would even be a shortcut, let alone instantaneous!
I don't get from '"no reason to suppose" only short' to '"*only* be
long"'. What I meant by "no reason to suppose" was that there might be
short ones, or there might be long ones.
Most or many SFnal wormholes, I think, are discovered rather than made.
I agree that *if* you could make a wormhole, you could probably make
a short one. Maybe. Perhaps. But it's less a strain to imagine
discovering one than to imagine a human civilisation having the
capability any time soon.
OTOH, I suppose a wormole network constructed by a vanished superior
civilisation could be assumed to have nice properties. It always feels
to me a bit of a cheat, though, to use a vanished superior civilisation
as a deus ex machina.
> > OTOH, if you were driving your car, entering "hyperspace" would be
> > like taking off and flying: you are "entering" a third dimension (up).
>
> You said this before, but which dimension do you think the wormholes are
> going through?! They're orthogonal too*! It's not as if they're
> travelling in the same dimensions as we are.
> * Or rather they at least have to have an orthogonal element.
I've not explained it clearly enough then: a wormhole is part of
our universe. It's a strangely distorted and stretched part, but it's
in the same relationship as your sleeve is to your coat. Whereas
hyperspace is *not* part of your coat.
Mathematically, a wormhole doesn't even *need* extra dimensions to
exist in. (This is impossible to visualise if you imagine our
universe to be "curved" in some sort of flat (Euclidean)
hyperdimension.)
Brian could probably explain this better than I can. Imagine a
sphere. You probably think of it as a two-dimensional surface
curved around in the third dimension so that it joins up with
itself. But that's not what a sphere is. A sphere is a two-dimensional
surface which has certain properties (e.g. the formula for the
distance, along the sphere, between any two points). There's absolutely
no logical (or mathematical) reason why anything more than two
dimensions are needed for it *unless* you assume it must be embedded
in some set of "flat" dimensions (where flat means obeys Euclidean
geometry). But there's no reason to believe in Euclidean geometry
as being "better" or more natural than any other kind.
To put it succinctly: a "curved" space doesn't need a higher-dimensional
space to curve in! It can be curved perfectly well on its own.
Or, to say the same thing: a "flat" space doesn't need a higher-
dimensional space to be flat in! Otherwise, you get an infinite
regress, and for any N-dimensional space, you have to posit an
N+1-dimensional space for the N-dimensional space to exist in.
Jonathan
Julian Flood
> Or, to say the same thing: a "flat" space doesn't need a higher-
> dimensional space to be flat in! Otherwise, you get an infinite
> regress, and for any N-dimensional space, you have to posit an
> N+1-dimensional space for the N-dimensional space to exist in.
You may think you're very clever, young man, but it's N+1 space all the
way down.
JF
<thinks> There must be a story in that.
Chris Dollin
J W Dunne's [1] "serial time" had an infinite number of /time/
dimensions.
> JF
> <thinks> There must be a story in that.
And James Blish referred to it (making light use of) in
_Jack of Eagles_.
But one could do something /else/ with infinite spare space
dimensions. Bet they bugger up present-day physics something
awful.
[1] Name from memory; it's been yearsnyears. Non-fiction. Non-fact
too, but does that matter?
--
Adventures In Sparespace! Hedgehog
Notmuchhere: http://www.electric-hedgehog.net/
Otherface: Jena RDF/Owl toolkit http://jena.sourceforge.net/
Gruff
> Gruff <gruffsta...@googlemail.com> wrote:
>
>> Jonathan L Cunningham wrote:
> (snip)
>
>>> In hyperspace, unless the speed of light exactly matches, the distance
>>> will be non-zero: either timelike if the speed of light is greater, or
>>> spacelike if less.[*]
>> I'm not quite clear what you're trying to say here. Which distance?
>>
>>> So the two spaces are a different "shape" and can *not* be fitted
>>> together.
>> *balk* er... mapping? There's nothing unreasonable about assuming that
>
> You can't map, say, a torus onto a sphere. They're different shapes.
Agreed you can't map a torus onto a sphere because they're topologically
different. But two spaces with different values for c are not, AFAIK.
Yes they're different *shapes* but they have the same *topology* (don't
they?), in the same way that an egg is a different shape to a football,
but topologically identical.
Maybe I've misunderstood.
Gruff
I think we're at cross purposes over types of hyperspace.
>
> Mathematically, a wormhole doesn't even *need* extra dimensions to
> exist in. (This is impossible to visualise if you imagine our
> universe to be "curved" in some sort of flat (Euclidean)
> hyperdimension.)
>
> Brian could probably explain this better than I can. Imagine a
> sphere. You probably think of it as a two-dimensional surface
> curved around in the third dimension so that it joins up with
> itself. But that's not what a sphere is. A sphere is a two-dimensional
> surface which has certain properties (e.g. the formula for the
> distance, along the sphere, between any two points). There's absolutely
> no logical (or mathematical) reason why anything more than two
> dimensions are needed for it *unless* you assume it must be embedded
> in some set of "flat" dimensions (where flat means obeys Euclidean
> geometry). But there's no reason to believe in Euclidean geometry
> as being "better" or more natural than any other kind.
>
> To put it succinctly: a "curved" space doesn't need a higher-dimensional
> space to curve in! It can be curved perfectly well on its own.
I probably need to brush up on my GR. Whilst I accept that curvature
can be accounted for without extra dimensions (and that such curvature
would be experienced as force), I don't believe this can be extended to
wormholes because they change the topology in such a way that you *need*
the extra dimension otherwise you end up with 2:1 or n:1 mapping.
> Or, to say the same thing: a "flat" space doesn't need a higher-
> dimensional space to be flat in! Otherwise, you get an infinite
> regress, and for any N-dimensional space, you have to posit an
> N+1-dimensional space for the N-dimensional space to exist in.
This isn't true. You only have to invoke an extra dimension if you want
to punch a hole in the ones you already know to exist.
Tux Wonder-Dog
> Discussion/question.
>
> I'm an engineer (software), there is nothing that bugs me more than
> wrong science in Sci Fi novels. However, I don't have a clue where to
> start on my own tech research. I've finally found a story/characters
> that seem to demand I write about them. This is good, usually my
> interest in an idea withers and dies very quickly.
>
<snip>
> Where/how do you start your tech building? Little stuff (like computer
> concepts, weapons, etc) I can handle but I've got zero background in
> the science of moving a ship from one place to another. Wormholes,
> hyperdrive, lightspeed, the possibilities seem endless. So where do
> YOU start?
I stick to believable extrapolation for the _human_ interstellar transport -
eg, sublight, zero-point energy extraction (as gamma radiation) together
with a set of filters/buffers to turn ionizing radiation into a high-speed
stream of light atoms and molecules. Arthur C Clark got that meme started,
so I'm relying on authority, true, but it does make sense.
For the aliens, I stick to handwavium and unobtanium, since by definition, a
truly advanced technology is indistinguishable from magic, and an
insufficently advanced technology is no threat - except on a purely
personal level.
Wesley Parish
>
> Chris
--
"Good, late in to more rewarding well." "Well, you tonight. And I was
lookintelligent woman of Ming home. I trust you with a tender silence." I
get a word into my hands, a different and unbelike, probably - 'she
fortunate fat woman', wrong word. I think to me, I justupid.
Let not emacs meta-X dissociate-press write your romantic dialogs...!!!
Monique Y. Mudama
I have no problem with any of that =) In fact, it sounds great. I
have, however, read science fiction in which the story seems to be
primarily a vehicle for talking about how the science of the particular
world being described works. Yecch. Although I'm sure it's great for
some group of readers, or there wouldn't be so much of it.
--
monique
Jonathan L Cunningham
> Julian Flood wrote:
>
> > Jonathan L Cunningham wrote:
> >
> >> Or, to say the same thing: a "flat" space doesn't need a higher-
> >> dimensional space to be flat in! Otherwise, you get an infinite
> >> regress, and for any N-dimensional space, you have to posit an
> >> N+1-dimensional space for the N-dimensional space to exist in.
> >
> > You may think you're very clever, young man, but it's N+1 space all the
> > way down.
Actually, I was paraphrasing Sir Arthur Eddington, who said it in
a book.
> J W Dunne's [1] "serial time" had an infinite number of /time/
> dimensions.
I read that when I was still at school. I was too young to realise
it was bollocks, and assumed I had failed to understand it.
Years later, when I realised it was bollocks, I concluded (incorrectly)
that all philosophy was bollocks. More years later, I realised
that Sturgeon's Law[*] applied to philosophy as much as anything else.
One of the really, really, big, massive, failings of philosophers
thinking about the philosophy of time was not spotting that space
and time were linked, in the way that Einstein pointed out. It should
be a Warning to all thinkers: it doesn't matter how smart you are, you
are possibly overlooking something. You may be assuming things that are
not true without realising it.
Even Descartes did that. He tried to throw away everything and
started with "I think, therefore I am". I think that was assuming
too much. "I think, therefore something is" would be better. But
what implicit assumptions does it depend on?
Jonathan
[*] According to Wikipedia "Sturgeon's Revelation" - but in his place
I'd rather have it be my Law.
Jonathan L Cunningham
> I probably need to brush up on my GR. Whilst I accept that curvature
> can be accounted for without extra dimensions (and that such curvature
> would be experienced as force), I don't believe this can be extended to
> wormholes because they change the topology in such a way that you *need*
> the extra dimension otherwise you end up with 2:1 or n:1 mapping.
>
> > Or, to say the same thing: a "flat" space doesn't need a higher-
> > dimensional space to be flat in! Otherwise, you get an infinite
> > regress, and for any N-dimensional space, you have to posit an
> > N+1-dimensional space for the N-dimensional space to exist in.
>
> This isn't true. You only have to invoke an extra dimension if you want
> to punch a hole in the ones you already know to exist.
I believe your last statement is simply incorrect. I don't see where you
get it from. Well, no point arguing about it.
I own a pair of trousers (pants to Americans). At the waist the
cross-section is a loop (I can put a belt around it). Lower down,
the cross-section is two separate loops. This did not require punching
holes in the original loop - it required deforming it into a figure
eight (at the crotch) and then separating the two loops of the eight.
None of that required a third dimension. (As it happens, my trousers
exist in a 3D space -- but they don't *need* to.)
Jonathan
Jonathan L Cunningham
> Jonathan L Cunningham wrote:
> > You can't map, say, a torus onto a sphere. They're different shapes.
>
> Agreed you can't map a torus onto a sphere because they're topologically
> different. But two spaces with different values for c are not, AFAIK.
> Yes they're different *shapes* but they have the same *topology* (don't
> they?), in the same way that an egg is a different shape to a football,
> but topologically identical.
We are now talking about the "overspace" style of hyperspace, not the
"crumpled tissue" style.
> Maybe I've misunderstood.
Perhaps my intuition is wrong. It should be easy to demonstrate: it's
only necessary for someone to propose a suitable mapping.
Given a point (x',y',z',t') in hyperspace, what point does it correspond
to in normal space?
The usual SFnal mapping is linear: x' -> kx, y' -> ky etc. And the
assumption is that t' = t, i.e. time is the same in normal space and
in hyperspace.
That won't work.[*]
What else can you (or anyone) come up with?
Jonathan
[*] Unless my visualisation is hopelessly wrong. But, although I'm
poor at visualising temples in stone age cultures[**], I'm only
equally poor at visualising four-dimensional geometry: not worse :-).
[**] Reference to some of my earlier posts about description.
Gerry Quinn
sp...@sofluc.co.uk.invalid says...
> One of the really, really, big, massive, failings of philosophers
> thinking about the philosophy of time was not spotting that space
> and time were linked, in the way that Einstein pointed out.
That's by no means an incontestable assertion.
- Gerry Quinn
Chris Dollin
That they're linked, or that philosophers hadn't spotted it?
--
Relativistic Hedgehog
Zeborah
> I own a pair of trousers (pants to Americans). At the waist the
> cross-section is a loop (I can put a belt around it). Lower down,
> the cross-section is two separate loops. This did not require punching
> holes in the original loop - it required deforming it into a figure
> eight (at the crotch) and then separating the two loops of the eight.
And how do you separate them without punching holes in the fabric?
Zeborah
--
Gravity is no joke.
http://www.geocities.com/zeborahnz/
Gruff
> Gruff <gruffsta...@googlemail.com> wrote:
>
>> I probably need to brush up on my GR. Whilst I accept that curvature
>> can be accounted for without extra dimensions (and that such curvature
>> would be experienced as force), I don't believe this can be extended to
>> wormholes because they change the topology in such a way that you *need*
>> the extra dimension otherwise you end up with 2:1 or n:1 mapping.
>>
>>> Or, to say the same thing: a "flat" space doesn't need a higher-
>>> dimensional space to be flat in! Otherwise, you get an infinite
>>> regress, and for any N-dimensional space, you have to posit an
>>> N+1-dimensional space for the N-dimensional space to exist in.
>> This isn't true. You only have to invoke an extra dimension if you want
>> to punch a hole in the ones you already know to exist.
>
> I believe your last statement is simply incorrect. I don't see where you
> get it from. Well, no point arguing about it.
Sorry, my bad. What I wrote wasn't what I meant. What I *meant* was
punch a hole in the sense of creating a connecting tunnel between two
parts, e.g. punch a _wormhole_, which (I believe) changes the topology.
>
> I own a pair of trousers (pants to Americans). At the waist the
> cross-section is a loop (I can put a belt around it). Lower down,
> the cross-section is two separate loops. This did not require punching
> holes in the original loop - it required deforming it into a figure
> eight (at the crotch) and then separating the two loops of the eight.
Actually, assuming the holes are open, it does require punching a hole
in this example. 'Deforming it into a figure eight' is a deceptive way
of saying creating a join which is topologically identical to punching a
hole.
> None of that required a third dimension. (As it happens, my trousers
> exist in a 3D space -- but they don't *need* to.)
Perhaps we're moving away from the original point here, but any finite
space of any finite number of apparent dimensions can be mapped onto a
single dimension. If the dimensions are infinite, this is no longer
true and one *could* conclude that the dimensions are real, rather than
perceived.
Gruff
> Gruff <gruffsta...@googlemail.com> wrote:
>
>> Jonathan L Cunningham wrote:
>
>>> You can't map, say, a torus onto a sphere. They're different shapes.
>> Agreed you can't map a torus onto a sphere because they're topologically
>> different. But two spaces with different values for c are not, AFAIK.
>> Yes they're different *shapes* but they have the same *topology* (don't
>> they?), in the same way that an egg is a different shape to a football,
>> but topologically identical.
>
> We are now talking about the "overspace" style of hyperspace, not the
> "crumpled tissue" style.
>
>> Maybe I've misunderstood.
>
> Perhaps my intuition is wrong. It should be easy to demonstrate: it's
> only necessary for someone to propose a suitable mapping.
>
> Given a point (x',y',z',t') in hyperspace, what point does it correspond
> to in normal space?
Isn't that an absolute position?
> The usual SFnal mapping is linear: x' -> kx, y' -> ky etc. And the
> assumption is that t' = t, i.e. time is the same in normal space and
> in hyperspace.
>
> That won't work.[*]
>
> What else can you (or anyone) come up with?
>
> Jonathan
> [*] Unless my visualisation is hopelessly wrong. But, although I'm
> poor at visualising temples in stone age cultures[**], I'm only
> equally poor at visualising four-dimensional geometry: not worse :-).
>
> [**] Reference to some of my earlier posts about description.
Gruff
nyra
>
> Jonathan L Cunningham <sp...@sofluc.co.uk.invalid> wrote:
>
> > I own a pair of trousers (pants to Americans). At the waist the
> > cross-section is a loop (I can put a belt around it). Lower down,
> > the cross-section is two separate loops. This did not require punching
> > holes in the original loop - it required deforming it into a figure
> > eight (at the crotch) and then separating the two loops of the eight.
>
> And how do you separate them without punching holes in the fabric?
I'd call that 'cutting to shape', not 'punching holes'.
Anyway, all of my trousers consist mainly of four large pieces of
cloth; and if i wanted to describe the way the trousers are generated,
i'd talk about the seams - the two outer seams running all the way
from the waist to the foot, the inseam which runs from one foot to the
other via the lower abdomen and the one running from the front to the
back via the crotch (where it crosses the inseam).
Now, if we interpreted these major seams as the spatial co-ordinates
and time as the person wearing those trousers, we'll have a space-time
universe in which there are two mirror twins of one spatial
co-ordinate (the two outer seams), time would be nondirectional and
only part of it would actually be inside the trouser-universe; and
only during the day, at night the trousers would be cast aside and be
dormant - obviously, nothing can happen in the universe if there's no
Time in it.
I'm not sure i want to live in such a universe. And i haven't even
considered the Trousers of Time becoming threadbare with wear, or the
Pyjama Pants or Edible Knickers of Time.
--
Se on Jumalan sana, sanoi mies,
kun akkansa raamatulla löi.
Gerry Quinn
hedgehog.net says...
> Gerry Quinn wrote:
> > In article <1hlvvl1.1ylxwj9gbcmb3N%sp...@sofluc.co.uk.invalid>,
> > sp...@sofluc.co.uk.invalid says...
> >
> >> One of the really, really, big, massive, failings of philosophers
> >> thinking about the philosophy of time was not spotting that space
> >> and time were linked, in the way that Einstein pointed out.
> >
> > That's by no means an incontestable assertion.
>
> That they're linked, or that philosophers hadn't spotted it?
That they're linked in the way Einstein pointed out.
- Gerry Quinn
Jonathan L Cunningham
> Jonathan L Cunningham wrote:
> > Gruff <gruffsta...@googlemail.com> wrote:
> >> This isn't true. You only have to invoke an extra dimension if you want
> >> to punch a hole in the ones you already know to exist.
> >
> > I believe your last statement is simply incorrect. I don't see where you
> > get it from. Well, no point arguing about it.
>
> Sorry, my bad. What I wrote wasn't what I meant. What I *meant* was
> punch a hole in the sense of creating a connecting tunnel between two
> parts, e.g. punch a _wormhole_, which (I believe) changes the topology.
This may be why some ideas about making a wormhole start by "growing"
a tiny one found in the quantum foam (or choose your own poetic
metaphor). Growing an existing wormhole wouldn't require a topology
change.
However, I still don't see any reason why you'd need an extra
dimension. Consider "folding space" in _Dune_ (and many other SF
stories). Or suppose, using some psychic ability, or by Zen
meditation or something I could cause New York and London to
coincide (same thing as "folding space"). Then I could be in both
places at once. And when I allowed them to separate, perhaps I
could choose which place to be in: which needn't be the same place
I started from.
That might also allow me to "grow" a wormhole between the two
places. A permanent "gateway" or "portal" for other people to
use. Yes, it could mean that the topology had changed -- but I still
don't see any need for another dimension.
"Yes, but ..." you might say. I would agree that it might be
*reasonable* to suppose that some kind of other dimension was involved.
Particularly if it made the mathematics simpler. But it's just as
reasonable (I think) to apply Occam's depilation cream, and ask why
you want to invoke another dimension.
> > I own a pair of trousers (pants to Americans). At the waist the
> > cross-section is a loop (I can put a belt around it). Lower down,
> > the cross-section is two separate loops. This did not require punching
> > holes in the original loop - it required deforming it into a figure
> > eight (at the crotch) and then separating the two loops of the eight.
>
> Actually, assuming the holes are open, it does require punching a hole
> in this example. 'Deforming it into a figure eight' is a deceptive way
> of saying creating a join which is topologically identical to punching a
> hole.
>
> > None of that required a third dimension. (As it happens, my trousers
> > exist in a 3D space -- but they don't *need* to.)
>
> Perhaps we're moving away from the original point here, but any finite
> space of any finite number of apparent dimensions can be mapped onto a
> single dimension. If the dimensions are infinite, this is no longer
> true and one *could* conclude that the dimensions are real, rather than
> perceived.
Well, there are notions of continuity involved. Ideally, you'd like
adjacent bits of your body to be adjacent when you arrive.
There *are* some kinds of stardrive hyperspace "jumps" which might
scramble the crew and passengers' constituent particles, and unscramble
them on arrival. It's hard to imagine *living* on a ship in hyperspace
if you used the sort of mapping which smeared out your body cells onto
isolated points light-years apart! :-). But it's not hard to imagine
some kind of "jump" drive that did that, then reassembled the bits in
correct order in a new location.
Jonathan
Jonathan L Cunningham
> Jonathan L Cunningham wrote:
> > Gruff <gruffsta...@googlemail.com> wrote:
> >
> >> Jonathan L Cunningham wrote:
> >
> >>> You can't map, say, a torus onto a sphere. They're different shapes.
> >> Agreed you can't map a torus onto a sphere because they're topologically
> >> different. But two spaces with different values for c are not, AFAIK.
> >> Yes they're different *shapes* but they have the same *topology* (don't
> >> they?), in the same way that an egg is a different shape to a football,
> >> but topologically identical.
> >
> > We are now talking about the "overspace" style of hyperspace, not the
> > "crumpled tissue" style.
> >
> >> Maybe I've misunderstood.
> >
> > Perhaps my intuition is wrong. It should be easy to demonstrate: it's
> > only necessary for someone to propose a suitable mapping.
> >
> > Given a point (x',y',z',t') in hyperspace, what point does it correspond
> > to in normal space?
>
> Isn't that an absolute position?
It was intended to represent an arbitrary point (usually called an
event, when the fourth dimension is time) in hyperspace. The x' etc.
are variables. I put the primes on the hyperspace coordinates to
distinguish them from normal space coordinates (it feels more natural
that way around).
The point I'm making (in this subthread) is that one common SFnal
hyperspace assumes that "time" is somehow independent of space, and
even the same in hyperspace. If you (not you personally) make that
assumption, then the mapping will look different in different inertial
frames of reference.
One of the things this whole thread has brought up, is how many
*different* notions there are of what "hyperspace" might be -- many of
them, ISTM, are more suitable for a hard(ish) SF story than the simple
sort of hyperspace used in Weber's "Honor Harrington" universe. I keep
referring to that because it's so popular at the moment, not because I
think it's any worse than many others.
The significant *writing* point is that Weber's hyperspace was
"designed" to fit the needs of the story, ISTM, rather than the other
way about.
Jonathan
Gruff
> Gruff <gruffsta...@googlemail.com> wrote:
>
>> Jonathan L Cunningham wrote:
>>> Gruff <gruffsta...@googlemail.com> wrote:
>
>>>> This isn't true. You only have to invoke an extra dimension if you want
>>>> to punch a hole in the ones you already know to exist.
>>> I believe your last statement is simply incorrect. I don't see where you
>>> get it from. Well, no point arguing about it.
>> Sorry, my bad. What I wrote wasn't what I meant. What I *meant* was
>> punch a hole in the sense of creating a connecting tunnel between two
>> parts, e.g. punch a _wormhole_, which (I believe) changes the topology.
>
> This may be why some ideas about making a wormhole start by "growing"
> a tiny one found in the quantum foam (or choose your own poetic
> metaphor). Growing an existing wormhole wouldn't require a topology
> change
Not from itself no, but it is topologically different from the notion of
a smooth space without wormholes which was my point.
>
> However, I still don't see any reason why you'd need an extra
> dimension.
Well, in your scrunched paper example you already have the extra
dimension in place. All I was pointing out is that a wormhole travels
through this same dimension, but I agree there are alternative
'realities' to explain both the wormhole and indeed the various
hyperspaces we ended up discussing. It's been interesting!
> Consider "folding space" in _Dune_ (and many other SF
> stories). Or suppose, using some psychic ability, or by Zen
> meditation or something I could cause New York and London to
> coincide (same thing as "folding space"). Then I could be in both
> places at once. And when I allowed them to separate, perhaps I
> could choose which place to be in: which needn't be the same place
> I started from.
Or use of the infamous infinite improbability drive... where's that cup
of tea gone?
>
> That might also allow me to "grow" a wormhole between the two
> places. A permanent "gateway" or "portal" for other people to
> use. Yes, it could mean that the topology had changed -- but I still
> don't see any need for another dimension.
>
> "Yes, but ..." you might say. I would agree that it might be
> *reasonable* to suppose that some kind of other dimension was involved.
> Particularly if it made the mathematics simpler. But it's just as
> reasonable (I think) to apply Occam's depilation cream, and ask why
> you want to invoke another dimension.
As I said, you'd already stated it existed for your hyperspace. I was
just using it. Nonetheless, I'm still not entirely convinced that you
can have a wormhole without the extra dimension. I'm wondering if our
ideas of what a wormhole is are different. Maybe if we go down a
dimension to 3d (2space + 1time) it might be easier to see. Still, it's
hard to chat about this stuff over email.
>
>>> I own a pair of trousers (pants to Americans). At the waist the
>>> cross-section is a loop (I can put a belt around it). Lower down,
>>> the cross-section is two separate loops. This did not require punching
>>> holes in the original loop - it required deforming it into a figure
>>> eight (at the crotch) and then separating the two loops of the eight.
>> Actually, assuming the holes are open, it does require punching a hole
>> in this example. 'Deforming it into a figure eight' is a deceptive way
>> of saying creating a join which is topologically identical to punching a
>> hole.
>>
>>> None of that required a third dimension. (As it happens, my trousers
>>> exist in a 3D space -- but they don't *need* to.)
>> Perhaps we're moving away from the original point here, but any finite
>> space of any finite number of apparent dimensions can be mapped onto a
>> single dimension. If the dimensions are infinite, this is no longer
>> true and one *could* conclude that the dimensions are real, rather than
>> perceived.
>
> Well, there are notions of continuity involved. Ideally, you'd like
> adjacent bits of your body to be adjacent when you arrive.
Not really. Continuity is perceived. Imagine a 3d array. It's
actually stored in the computer as a 1D array. The contiguity of
adjacent elements is something that's "handled" by an abstraction layer.
Same thing could be true of spacetime.
Chris Dollin
> In article <ctLPg.3107$5t4...@fe3.news.blueyonder.co.uk>, eh@electric-
> hedgehog.net says...
>> Gerry Quinn wrote:
>> > In article <1hlvvl1.1ylxwj9gbcmb3N%sp...@sofluc.co.uk.invalid>,
>> > sp...@sofluc.co.uk.invalid says...
>> >
>> >> One of the really, really, big, massive, failings of philosophers
>> >> thinking about the philosophy of time was not spotting that space
>> >> and time were linked, in the way that Einstein pointed out.
>> >
>> > That's by no means an incontestable assertion.
>>
>> That they're linked, or that philosophers hadn't spotted it?
>
> That they're linked in the way Einstein pointed out.
Special, or general?
--
Fork Hedgehog
Tim S
>
> There *are* some kinds of stardrive hyperspace "jumps" which might
> scramble the crew and passengers' constituent particles, and unscramble
> them on arrival. It's hard to imagine *living* on a ship in hyperspace
> if you used the sort of mapping which smeared out your body cells onto
> isolated points light-years apart! :-). But it's not hard to imagine
> some kind of "jump" drive that did that, then reassembled the bits in
> correct order in a new location.
People can't even reassemble flat-pack furniture.
Tim
Bob Throllop
Julian Flood wrote:
> Ben Crowell wrote:
>
> >This reminds me of the standard advice given to aspiring young jazz
musicians: learn all your scales and arpeggios in all twelve keys,
and then forget about them and play music. In other words, if someone
in the audience is thinking, "That cat really knows his scales,"
you've failed.
>
> Please tell me it's true. Somewhere people still call cool dudes 'cats'.
> No, David, not you.
He didn't mean you've failed because you made your scales too obvious;
you failed because you're playing to an audience of squa^H^H^H
out-of-date people.
Gerry Quinn
e...@electric-hedgehog.net says...
> Gerry Quinn wrote:
> > In article <ctLPg.3107$5t4...@fe3.news.blueyonder.co.uk>, eh@electric-
> > hedgehog.net says...
> >> Gerry Quinn wrote:
> >> > In article <1hlvvl1.1ylxwj9gbcmb3N%sp...@sofluc.co.uk.invalid>,
> >> > sp...@sofluc.co.uk.invalid says...
> >> >
> >> >> One of the really, really, big, massive, failings of philosophers
> >> >> thinking about the philosophy of time was not spotting that space
> >> >> and time were linked, in the way that Einstein pointed out.
> >> >
> >> > That's by no means an incontestable assertion.
> >>
> >> That they're linked, or that philosophers hadn't spotted it?
> >
> > That they're linked in the way Einstein pointed out.
>
> Special, or general?
Both link space and time via special relativity. General relativity is
just special relativity plus the principle of equivalence.
While general relativity is easier to contest (the principle of
equivalence can be attacked while leaving special relativity alone)
both are perfectly contestable.
- Gerry Quinn
Michelle Bottorff
> The significant *writing* point is that Weber's hyperspace was
> "designed" to fit the needs of the story, ISTM, rather than the other
> way about.
I'm not entirely certain how significant a writing point that is,
actually.
If you devellop them at the same time it gets really hard to tell which
was designed to suit the needs of what, and readers often guess wrongly
about that kind of thing anyway.
To me the significant point is that there are a lot of ideas out there
to choose from, in a positive rainbow of flavors, and I don't know why
it matters whether you choose one first and then write a story about it,
or if you come up with a story and then choose the idea that best fits
it. Different approaches will work differently for different writers.
--
Michelle Bottorff -> Chelle B. -> Shelby
L. Shelby, Writer http://www.lshelby.com/
Livejournal http://lavenderbard.livejournal.com/
rec.arts.sf.composition FAQ http://www.lshelby.com/rasfcFAQ.html
Ric Locke
And in fact this appears (to this non-mathematician) to be one approach to
Unification: an assumption that spacetime is quantized, and there's really
no such thing as a photon, c being a reflection of the rate at which
excited quanta share energy with one another.
At the other end of the scale, considerations of entropy applied to black
holes lead some to conclude that the Universe is, in fact, two dimensional,
with the third dimension being an artifact of perception. Either that or
the event horizon of a black hole is three-dimensional, not in external
appearance but in internal structure, and /that/ seems not to fit the
equations.
Neither theory appears to lead immediately to easy FTL, but one can
continue to hope.
Regards,
Ric
--
Posted via a free Usenet account from http://www.teranews.com
Chris Dollin
Clearly they're contest*able* - being scientific theories - so,
I wondered if you had something /specific/ and preferably
empirical in mind, given that while there have been some small
difficulties [1] integrating the relativities and quantum theory,
relativity is, as I understand it, still empirically successful.
(Not that I wouldn't abandon it in an instant if I could make a
good story on those grounds, of course.)
[1] Please to remember my nationality.
--
C Hedgehog
Gerry Quinn
> Gerry Quinn wrote:
> >> >> > That's by no means an incontestable assertion.
> >> >>
> >> >> That they're linked, or that philosophers hadn't spotted it?
> >> >
> >> > That they're linked in the way Einstein pointed out.
> >>
> >> Special, or general?
> >
> > Both link space and time via special relativity. General relativity is
> > just special relativity plus the principle of equivalence.
> >
> > While general relativity is easier to contest (the principle of
> > equivalence can be attacked while leaving special relativity alone)
> > both are perfectly contestable.
>
> Clearly they're contest*able* - being scientific theories - so,
> I wondered if you had something /specific/ and preferably
> empirical in mind, given that while there have been some small
> difficulties [1] integrating the relativities and quantum theory,
> relativity is, as I understand it, still empirically successful.
In the fight between general relativity and quantum theory, hardly
anyone is betting on the former any more, I suspect. As far as I can
tell Stephen Hawking's recent work implies that general relativity
breaks down outside black holes, and if he's right that means that all
the fancy stuff involving non-trivial topologies is essentially dead,
and spacetime can be treated as fundamentally flat. Really, general
relativity is in trouble because it doesn't fit in with the second law
of thermodynamics, and never did. It's taken somewhat too long for
people to start generally realising that.
If spacetime can be treated as flat, then special relativity still
stands as a symmetry that has never been shown to be violated, and
physicists might prefer it from the point of view of simplicity. But a
model similar to the Lorentz-Poincare ether model, in which a
fundamental space and time as understood by Galileo exist, still works
quite well. (Indeed, if you apply a sum over histories approach as
demanded by quantum theory, I think it's quite hard to distinguish
between that and special relativity. If you sum over every possible
ether, how is that different from saying there is no preferred frame?
But in every ether you sum over, time and space are separate.)
If we ever discover FTL travel, the Lorentz-Poincare model will be
resurrected in a flash. It doesn't offend experiment in any strong
way.
So philosophically, there's no really strong reason to suppose that
space and time are not fundamentally separate. Quantum mechanics is a
lot more troublesome, though there are different ways to interpret it.
You ask for empirical evidence, so I will ask: where is the empirical
demonstration that space and time *are* linked in the fashion proposed
by Einstein? If this is not demonstrable, then failing to spot that
they are linked is hardly such a massive failure. It may yet turn out
that those philosophers who didn't make the leap were right about time
and space after all!
Julian Barbour has proposed that there is only space; that time is an
illusion. I wouldn't be surprised if that was the way ideas drift, in
spaces containing histories that resemble this space.
- Gerry Quinn
Gerry Quinn
T...@timsilverman.demon.co.uk says...
>
> People can't even reassemble flat-pack furniture.
So THAT's why we can't distinguish between space and time, or even
figure out how many dimensions there are! God has assembled the
universe incorrectly...
- Gerry Quinn
Chris Dollin
Forgive me if that comes over as handwaving. What's the replacment
for GR for dealing with gravitation? (Can you summarise the
thermodynamic argument in layish terms?)
> You ask for empirical evidence, so I will ask: where is the empirical
> demonstration that space and time *are* linked in the fashion proposed
> by Einstein?
Particle accelerators work. Mu-mesons make it from the top to
the bottom of the atmosphere. (SR not GR, but for the purposes
of the thread I'm not sure it matters.)
To the best of my -- limited -- knowledge, GR works as a theory
for gravitation (eg Mercury's orbit). I'm not really bothered
what happens inside black holes, since you can't see inside them
anyway.
> Julian Barbour has proposed that there is only space; that time is an
> illusion.
Lunchtime doubly so.
> I wouldn't be surprised if that was the way ideas drift, in
> spaces containing histories that resemble this space.
It's easy to dismiss things as illusions, but one still has to
explain why /this/ illusion, doesn't one?
--
Real Hedgehog
John W. Kennedy
> I own a pair of trousers (pants to Americans).
"Trousers" is perfectly well understood in the US. "Pants" is merely a
synonym.
--
John W. Kennedy
"The blind rulers of Logres
Nourished the land on a fallacy of rational virtue."
-- Charles Williams. "Taliessin through Logres: Prelude"
Gerry Quinn
> Gerry Quinn wrote:
> >> > While general relativity is easier to contest (the principle of
> >> > equivalence can be attacked while leaving special relativity alone)
> >> > both are perfectly contestable.
> >>
> >> Clearly they're contest*able* - being scientific theories - so,
> >> I wondered if you had something /specific/ and preferably
> >> empirical in mind, given that while there have been some small
> >> difficulties [1] integrating the relativities and quantum theory,
> >> relativity is, as I understand it, still empirically successful.
> >
> > In the fight between general relativity and quantum theory, hardly
> > anyone is betting on the former any more, I suspect. As far as I can
> > tell Stephen Hawking's recent work implies that general relativity
> > breaks down outside black holes, and if he's right that means that all
> > the fancy stuff involving non-trivial topologies is essentially dead,
> > and spacetime can be treated as fundamentally flat. Really, general
> > relativity is in trouble because it doesn't fit in with the second law
> > of thermodynamics, and never did. It's taken somewhat too long for
> > people to start generally realising that.
>
> Forgive me if that comes over as handwaving. What's the replacment
> for GR for dealing with gravitation? (Can you summarise the
> thermodynamic argument in layish terms?)
Nobody knows exactly what a quantum gravity theory will look like, but
almost everyone expects there will be one, and that GR will be amended.
As for the thermodynamic issue, look up 'black hole information
problem'. Singularities are inescapable in GR, and in essence
singularities mean 'this model breaks down, at the singularity or at
some point before it'.
> > You ask for empirical evidence, so I will ask: where is the empirical
> > demonstration that space and time *are* linked in the fashion proposed
> > by Einstein?
>
> Particle accelerators work. Mu-mesons make it from the top to
> the bottom of the atmosphere. (SR not GR, but for the purposes
> of the thread I'm not sure it matters.)
SR is stronger than GR anyway - it makes one less assumption. However,
models other than SR (i.e. variatios on the ether-based theory of
Lorentz and Poincare) can be made to explain those phenomena. Thus
there is no overwhelming philosophical reason why SR should be correct.
Therefore it cannot be said that philosophers made a blunder in not
discovering SR.
> To the best of my -- limited -- knowledge, GR works as a theory
> for gravitation (eg Mercury's orbit). I'm not really bothered
> what happens inside black holes, since you can't see inside them
> anyway.
GR works very well in such circumstances, and will continue to do so.
But the question was about what philosophers should have believed! GR
could be the weak field limit of an underlying model of a very
different sort; it's curved spacetime need not represent a fundamental
aspect of reality.
> > Julian Barbour has proposed that there is only space; that time is an
> > illusion.
>
> Lunchtime doubly so.
>
> > I wouldn't be surprised if that was the way ideas drift, in
> > spaces containing histories that resemble this space.
>
> It's easy to dismiss things as illusions, but one still has to
> explain why /this/ illusion, doesn't one?
The idea is to start with the already baffling quantum mechanics, then
delve even further into its underlying roots. I don't say Barbour has
come up with the answer, but I think he is asking the right questions.
- Gerry Quinn
simp...@aol.com
mapping:
Okay! I'm thinking this way:
EXPRESSING 2 DIMENSIONS IN 1 DIMENSION.
Start with a line.
______
If you had to express 2 dimensions in
1 dimension, how would you do it?
You'd use two lines, and
just remember that the 2nd
line is going in a dimension you
cannot directly manipulate.
________
________
EXPRESSING 3 DIMENSIONS IN 2 DIMENSIONS.
Okay - you have two dimensions.
|
|
|
|_________
You want to express 3 dimensions in
2 dimensions?
|
|
|
|_________
|
|
|
|_________
You would just have to remember that the
2nd |_ is representing the 3rd dimension -
going "up" in a direction you can't directly
manipulate [but since we're in 3 dimensions,
we could simply pick up the 2nd |_ and flip
it around into a 3 dimensional shape).
But as a 2 dimensional being, you wouldn't
be able to use the parlor trick of
making a 3D-looking box in 2 dimensions,
because you can only think 3 dimensionally in
theory - perhaps even mathematically.
EXPRESSING 4 DIMENSIONS IN 3 DIMENSIONS
Okay - we're getting limited already,
because e-mail is 2 dimensions.
You have a 3D cube.
You want to express a 4D cube.
How to do it? Same way!
You have another cube.
Two cubes.
But the two cubes are really 1 cube, just
stretching upwards in a direction that
we cannot perceive.
Notice what's happening here!!!
Each dimension is STILL being expressed
by a 1 dimensional thing: The ___________.
For 2 dimensions, you have a GROUP of
2 or more __________
for 3 dimensions you have a GROUP of
3 or more ___________
For 4 dimensions, you have a group of
4 or more ___________
OR:
You have two dimensions:
|
|___
To get three dimensions, you
need TWO of these:
|
|___
|
|___
always remembering that the 2nd one
is flipped 'up', towards you.
Now, same logic:
You have 3 dimensions.
A cube.
To get 4 dimensions, you need
2 CUBES.
or
3 2D |_'s
or
4 ______ (lines).
To get FIVE dimensions,
you need 2 4D cubes at minimum.
*BUT* - since we are limited in
expressing ourselves in 3 dimensions,
we have other options!!
3 3D cubes will express 5 dimensions
minimally.
4 2D |_'s will express 5 dimensions
minimally as well...
5 ______'S will also express 5 dimensions.
[to see 5 dimensions in a common computer
application, see Microsoft Excel.
You have Row: 1 [one dimension)
You have Column A (2nd dimension)
You have Worksheet named: REPORT_1 (3rd dimension)
You have Filename named: NOV_REPORTS.XLS (4th dimension)
You have Directory named: C:\REPORTS\ (5th dimension)
etc.
It seems to get "flat" after you have the 4th dimension - but it's not!
NOTICE THIS!
A DIRECTORY (5) can have a collection of Excel FILES (4).
An Excel FILE (4) can have a collection of WORKSHEETS (3).
A WORKSHEET (3) can have a collection of COLUMNS (2)
A COLUMN (2) can have a collection of ROWS (1).
[and one single cell, which is in a row that is in a column,
that is in a worksheet, that is in a file, that is in a
directory, can reference ANY OTHER cell in any other
DIRECTORY, or FILE, or WORKSHEET, or COLUMN, or even ROW!] ]
A box inside of boxes is a way often used to
express multidimensionality.
Even time! -- Look at Russian nesting dolls.
They express, in one small package, 4 dimensions.
It is the same person, at different stages in time.
The Russian nesting doll is a 4 dimensional object.
Pretty neat stuff.
Thanks for listening - thoughts?
Kenneth
Gruff
> More along the lines of multidimensional
> mapping:
>
> Okay! I'm thinking this way:
>
> EXPRESSING 2 DIMENSIONS IN 1 DIMENSION.
>
> Start with a line.
>
> ______
>
>
> If you had to express 2 dimensions in
> 1 dimension, how would you do it?
>
> You'd use two lines, and
> just remember that the 2nd
> line is going in a dimension you
> cannot directly manipulate.
>
> ________
> ________
>
points to 2N.
Jonathan L Cunningham
> Jonathan L Cunningham <sp...@sofluc.co.uk.invalid> wrote:
>
> > The significant *writing* point is that Weber's hyperspace was
> > "designed" to fit the needs of the story, ISTM, rather than the other
> > way about.
>
> I'm not entirely certain how significant a writing point that is,
> actually.
>
> If you devellop them at the same time it gets really hard to tell which
> was designed to suit the needs of what, and readers often guess wrongly
> about that kind of thing anyway.
>
> To me the significant point is that there are a lot of ideas out there
> to choose from, in a positive rainbow of flavors, and I don't know why
> it matters whether you choose one first and then write a story about it,
> or if you come up with a story and then choose the idea that best fits
> it. Different approaches will work differently for different writers.
Let's argue about what I meant by "designed" then. I didn't quite mean
designed. And by the time I'd hedged it about with an "ISTM" my meaning
should be as clear as glass: obsidian, perhaps.
The significant writing point is that a camel with two humps is a
Bactrian camel, a dromedary has only one hump, and a rose by any other
name would smell as sweet.
Or, to put it another way, the name of the song is called "Haddock's
eyes" and if your story needs a camel with two humps, don't
invite dromedaries to the character auditions. But if you just need
an animal with humps, it doesn't matter. Still a good idea to count
the humps, though, in case it matters later in the plot.
Jonathan
Jonathan L Cunningham
> there is no overwhelming philosophical reason why SR should be correct.
> Therefore it cannot be said that philosophers made a blunder in not
> discovering SR.
[chorus] Oh, yes it can!
> > To the best of my -- limited -- knowledge, GR works as a theory
> > for gravitation (eg Mercury's orbit). I'm not really bothered
> > what happens inside black holes, since you can't see inside them
> > anyway.
>
> GR works very well in such circumstances, and will continue to do so.
> But the question was about what philosophers should have believed! GR
It's not about belief, but about asking the right questions. It
doesn't matter whether SR or GR is true, what matters is not asking
whether it is true and *that* is the failing of the philosophers:
they didn't even consider the possibility.
As for GR, it makes so many accurate and correct predictions (there
was an interesting list in a recent Sci.Am. of the several different
time distortion effects observable in the pulse rate of close binary
neutron stars which have been verified) that I find it hard to believe
that GR is irrelevant. Any theory that supersedes it will also have to
account for why GR is so accurate.
I have no idea how a theory that supersedes both GR and QM will combine
both. Equally, I have no idea how an entity can be both a particle and
a wave.
Even with SR, a photon hitting my retina from the Andromeda galaxy,
a journey which started two million years ago is, in the frame of
reference of the photon, simultaneously being emitted from a distant
star and hitting my retina. And, it's simultaneous because in that
frame of reference the distance is zero.
Jonathan
Marilee J. Layman
>Thanks for listening - thoughts?
Read _Flatland_.
--
Marilee J. Layman
http://mjlayman.livejournal.com/
Irina Rempt
> On 21 Sep 2006 08:11:58 -0700, simp...@aol.com wrote:
>
>>Thanks for listening - thoughts?
>
> Read _Flatland_.
Seconded. If you happen to be able to read Dutch, also _Bolland_
(Sphereland) by Dionijs Burger.
Irina
--
Vesta veran, terna puran, farenin. http://www.valdyas.org/irina/
Beghinnen can ick, volherden will' ick, volbringhen sal ick.
http://www.valdyas.org/foundobjects/index.cgi Latest: 08-Sep-2006
John W. Kennedy
> simp...@aol.com wrote:
>> More along the lines of multidimensional
>> mapping:
>>
>> Okay! I'm thinking this way:
>>
>> EXPRESSING 2 DIMENSIONS IN 1 DIMENSION.
>>
>> Start with a line.
>>
>> ______
>>
>>
>> If you had to express 2 dimensions in
>> 1 dimension, how would you do it?
>>
>> You'd use two lines, and
>> just remember that the 2nd
>> line is going in a dimension you
>> cannot directly manipulate.
>>
>> ________
>> ________
>>
> Er... that wouldn't work I'm afraid. You're trying have to map N*N
> points to 2N.
No problem. Number-of-the-continuum-squared is Number-of-the-continuum.
John W. Kennedy
> Marilee J. Layman wrote:
>
>> On 21 Sep 2006 08:11:58 -0700, simp...@aol.com wrote:
>>
>>> Thanks for listening - thoughts?
>> Read _Flatland_.
>
> Seconded. If you happen to be able to read Dutch, also _Bolland_
> (Sphereland) by Dionijs Burger.
It's been available in English for at least 40 years.
Brian M. Scott
<gruffsta...@googlemail.com> wrote in
<news:5JqdnZtVf6e...@eclipse.net.uk> in
rec.arts.sf.composition:
> simp...@aol.com wrote:
>> More along the lines of multidimensional
>> mapping:
>> Okay! I'm thinking this way:
>> EXPRESSING 2 DIMENSIONS IN 1 DIMENSION.
>> Start with a line.
>> ______
>> If you had to express 2 dimensions in
>> 1 dimension, how would you do it?
>> You'd use two lines, and
>> just remember that the 2nd
>> line is going in a dimension you
>> cannot directly manipulate.
>> ________
>> ________
>>
> Er... that wouldn't work I'm afraid. You're trying have to map N*N
> points to 2N.
It works fine: each point in R^2 corresponds to a pair of
points, one on one line, one on the other. Think of the two
lines as x- and y-axes, on which you're representing a point
(a, b) by its projections a and b. (Not 'N', though: the
number of points on a line is 2^\aleph_0, or c. And c * c =
c anyway.)
Brian
Carl Dershem
news:2236h2pp7b0j7gmgq...@4ax.com:
> On 21 Sep 2006 08:11:58 -0700, simp...@aol.com wrote:
>
>>Thanks for listening - thoughts?
>
> Read _Flatland_.
And then read "And he built a crooked house"
cd
--
The difference between immorality and immortality is "T". I like Earl
Grey.
Chris Dollin
Indeed. "Amended" needn't mean "having the geometric guts ripped
out of it". Maybe, maybe knot.
> As for the thermodynamic issue, look up 'black hole information
> problem'. Singularities are inescapable in GR, and in essence
> singularities mean 'this model breaks down, at the singularity or at
> some point before it'.
The infinities in QM being of course, of no consequence whatsoever.
(Isn't one of then problems that the handwaving [1] called
"renormalisation" doesn't work for QM-style gravitons and hence
the drive for the different approaches to quantised gravity?)
>> > You ask for empirical evidence, so I will ask: where is the empirical
>> > demonstration that space and time *are* linked in the fashion proposed
>> > by Einstein?
>>
>> Particle accelerators work. Mu-mesons make it from the top to
>> the bottom of the atmosphere. (SR not GR, but for the purposes
>> of the thread I'm not sure it matters.)
>
> SR is stronger than GR anyway - it makes one less assumption. However,
> models other than SR (i.e. variatios on the ether-based theory of
> Lorentz and Poincare) can be made to explain those phenomena. Thus
> there is no overwhelming philosophical reason why SR should be correct.
There are no "overwhelming philosophical reason"s for anything.
My understanding of the ether-based theories -- ie my condensation
about what I've heard about them, I make no claim to have
studied them -- is that their /only/ advantage over SR is that
you don't have to buy the space-time connexion (instead you have
to buy some otherwise-invisible physical mechanics). At which
point I would deploy Occam.
> Therefore it cannot be said that philosophers made a blunder in not
> discovering SR.
Eh?
Wasn't the blunder under discussion that they didn't [2] /consider/
a space-time linking? Not even the /possibility/ of one? (I don't
think it would have mattered if they'd produced a non-/relativistic/
linking.) Looks like a failure-of-imagination to me (I wouldn't
call it a "blunder" myself, but that might just be a difference of
lexicon between me and the OP.)
>> To the best of my -- limited -- knowledge, GR works as a theory
>> for gravitation (eg Mercury's orbit). I'm not really bothered
>> what happens inside black holes, since you can't see inside them
>> anyway.
>
> GR works very well in such circumstances, and will continue to do so.
> But the question was about what philosophers should have believed!
No, it's not about what they should have believed: it's about what
they didn't propose.
> GR could be the weak field limit of an underlying model of a very
> different sort; it's curved spacetime need not represent a fundamental
> aspect of reality.
I'm willing to grant the could-bes. I had read somewhere - wish I
could remember where - that there were GR effects that /couldn't/ be
(sensibly) done away with in that way: perhaps frame-dragging; but
that could be me bit-rotting or just false.
> The idea is to start with the already baffling quantum mechanics, then
> delve even further into its underlying roots.
/Both/ roots.
I'm am, not really apropos, reminded of "X is baffling. QM is baffling.
Hence QM explains X." (I have a particular X in mind).
[1] Yes, of course I am.
[2] I'm assuming that that they didn't isn't false to fact.
--
Far-Fetched Hedgehog
David Langford
<jwk...@attglobal.net> wrote:
>Irina Rempt wrote:
>> Marilee J. Layman wrote:
>>
>>> On 21 Sep 2006 08:11:58 -0700, simp...@aol.com wrote:
>>>
>>>> Thanks for listening - thoughts?
>>> Read _Flatland_.
>>
>> Seconded. If you happen to be able to read Dutch, also _Bolland_
>> (Sphereland) by Dionijs Burger.
>
>It's been available in English for at least 40 years.
Yes. I have the first US edition, dated 1965. Then there's Charles Hinton's
=An Episode of Flatland= from 1907, and Ian Stewart's =Flatterland= (2001).
Dave
--
David Langford | http://ansible.co.uk/
Latest nonfiction: =The SEX Column and other misprints= (Cosmos, 2005)
Latest fiction: =Different Kinds of Darkness= (Cosmos, 2004)
Gruff
assumption that the set was a) finite and b) (possibly) discrete
(perhaps misled by the drawings). I also assumed that he was talking
more than just expressing a position in terms of its vector components,
because his post followed an earlier discussion bewteen me and Jon about
dimensions.
Gruff
> Gruff wrote:
>> simp...@aol.com wrote:
>>> More along the lines of multidimensional
>>> mapping:
>>>
>>> Okay! I'm thinking this way:
>>>
>>> EXPRESSING 2 DIMENSIONS IN 1 DIMENSION.
>>>
>>> Start with a line.
>>>
>>> ______
>>>
>>>
>>> If you had to express 2 dimensions in
>>> 1 dimension, how would you do it?
>>>
>>> You'd use two lines, and
>>> just remember that the 2nd
>>> line is going in a dimension you
>>> cannot directly manipulate.
>>>
>>> ________
>>> ________
>>>
>> Er... that wouldn't work I'm afraid. You're trying have to map N*N
>> points to 2N.
>
> No problem. Number-of-the-continuum-squared is Number-of-the-continuum.
>
Gerry Quinn
simp...@aol.com says...
> More along the lines of multidimensional
> mapping:
In the Simpsons Halloween episode "Treehouse of Horror VI", Professor
Frink tries to explain Homer's disappearance into the third dimension:
Frink: (at chalkboard) Here is an ordinary square.
Chief Wiggum: Whoa, whoa, slow down, egghead!
Frink: But, suppose we extend the square beyond the two dimensions of
our universe, along the hypothetical Z-axis there.
Marge, Lisa, Bart, Ned, Reverend Lovejoy, Chief Wiggum, Dr. Hibbert,
Patty & Selma: [gasps] (as Frink draws a cube)
Frink: This forms a three-dimensional object known as a cube or a
Frinkahedron, in honour of its discoverer.
Homer: Help me! Are you helping me, or are you going on and on?
Frink: Oh, right. And, of course, within, we find the doomed
individual.
- Gerry Quinn
Gerry Quinn
sp...@sofluc.co.uk.invalid says...
> Gerry Quinn <ger...@DELETETHISindigo.ie> wrote:
>
> > there is no overwhelming philosophical reason why SR should be correct.
> > Therefore it cannot be said that philosophers made a blunder in not
> > discovering SR.
>
> [chorus] Oh, yes it can!
>
> > > To the best of my -- limited -- knowledge, GR works as a theory
> > > for gravitation (eg Mercury's orbit). I'm not really bothered
> > > what happens inside black holes, since you can't see inside them
> > > anyway.
> >
> > GR works very well in such circumstances, and will continue to do so.
> > But the question was about what philosophers should have believed! GR
>
> It's not about belief, but about asking the right questions. It
> doesn't matter whether SR or GR is true, what matters is not asking
> whether it is true and *that* is the failing of the philosophers:
> they didn't even consider the possibility.
Is it a failing that they didn't ask whether cats are really dogs?
Surely it cannot be asserted that failing to ask a *scientific*
question is a failing in philosophers, unless it is shown not only that
the science is true, but that it has philosophical implications.
It's not clear that even if relativity were completely true, it would
have philosophical implications (outside of branches of philosophy that
are better described as science). Time travel etc. would have
philosophical implications, but relativity does not predict such
things.
> As for GR, it makes so many accurate and correct predictions (there
> was an interesting list in a recent Sci.Am. of the several different
> time distortion effects observable in the pulse rate of close binary
> neutron stars which have been verified) that I find it hard to believe
> that GR is irrelevant. Any theory that supersedes it will also have to
> account for why GR is so accurate.
Of course. But that is a solved problem, so long as it resolves at low
energy to gravitons in flat spacetime.
> I have no idea how a theory that supersedes both GR and QM will combine
> both. Equally, I have no idea how an entity can be both a particle and
> a wave.
Best not to think of any entity as being both. One approach is to
think of the wave as the sum over all possible particle histories.
> Even with SR, a photon hitting my retina from the Andromeda galaxy,
> a journey which started two million years ago is, in the frame of
> reference of the photon, simultaneously being emitted from a distant
> star and hitting my retina. And, it's simultaneous because in that
> frame of reference the distance is zero.
And?
- Gerry Quinn
Gerry Quinn
> Gerry Quinn wrote:
> > Nobody knows exactly what a quantum gravity theory will look like, but
> > almost everyone expects there will be one, and that GR will be amended.
>
> Indeed. "Amended" needn't mean "having the geometric guts ripped
> out of it". Maybe, maybe knot.
I would disagree. Certainly it will mean that the geometry is not
fundamental. There may be Occam-like arguments about what the meaning
of 'fundamental' is.
> > As for the thermodynamic issue, look up 'black hole information
> > problem'. Singularities are inescapable in GR, and in essence
> > singularities mean 'this model breaks down, at the singularity or at
> > some point before it'.
>
> The infinities in QM being of course, of no consequence whatsoever.
> (Isn't one of then problems that the handwaving [1] called
> "renormalisation" doesn't work for QM-style gravitons and hence
> the drive for the different approaches to quantised gravity?)
Yes - but with quantum theory there is the possibility of progress.
The singularities have been proven to be intrinsic to GR. One way of
looking at it is that GR is complete and specific, a single theory
which is either right or wrong, and overwhelming grounds for believing
it wrong. We don't know what the *right* theory is, but we know it's
not GR.
> > SR is stronger than GR anyway - it makes one less assumption. However,
> > models other than SR (i.e. variatios on the ether-based theory of
> > Lorentz and Poincare) can be made to explain those phenomena. Thus
> > there is no overwhelming philosophical reason why SR should be correct.
>
> There are no "overwhelming philosophical reason"s for anything.
> My understanding of the ether-based theories -- ie my condensation
> about what I've heard about them, I make no claim to have
> studied them -- is that their /only/ advantage over SR is that
> you don't have to buy the space-time connexion (instead you have
> to buy some otherwise-invisible physical mechanics). At which
> point I would deploy Occam.
When Occam is presented as the strongest argument, it is always wrong.
> > Therefore it cannot be said that philosophers made a blunder in not
> > discovering SR.
>
> Eh?
>
> Wasn't the blunder under discussion that they didn't [2] /consider/
> a space-time linking? Not even the /possibility/ of one? (I don't
> think it would have mattered if they'd produced a non-/relativistic/
> linking.) Looks like a failure-of-imagination to me (I wouldn't
> call it a "blunder" myself, but that might just be a difference of
> lexicon between me and the OP.)
As I responded to Jonathan: only if it has philosophical implications
(appart from 'natural philosophy' a.k.a. science). And it's not clear
why it should.
> > GR could be the weak field limit of an underlying model of a very
> > different sort; it's curved spacetime need not represent a fundamental
> > aspect of reality.
>
> I'm willing to grant the could-bes. I had read somewhere - wish I
> could remember where - that there were GR effects that /couldn't/ be
> (sensibly) done away with in that way: perhaps frame-dragging; but
> that could be me bit-rotting or just false.
Frame dragging is certainly no problem. The only effects that can't be
done away with are those involving a non-trivial spacetime topology,
and no such thing has yet been observed...
- Gerry Quinn
Gruff
> John W. Kennedy wrote:
>> Gruff wrote:
>>> simp...@aol.com wrote:
>>>> More along the lines of multidimensional
>>>> mapping:
>>>>
>>>> Okay! I'm thinking this way:
>>>>
>>>> EXPRESSING 2 DIMENSIONS IN 1 DIMENSION.
>>>>
>>>> Start with a line.
>>>>
>>>> ______
>>>>
>>>>
>>>> If you had to express 2 dimensions in
>>>> 1 dimension, how would you do it?
>>>>
>>>> You'd use two lines, and
>>>> just remember that the 2nd
>>>> line is going in a dimension you
>>>> cannot directly manipulate.
>>>>
>>>> ________
>>>> ________
>>>>
>>> Er... that wouldn't work I'm afraid. You're trying have to map N*N
>>> points to 2N.
>>
>> No problem. Number-of-the-continuum-squared is Number-of-the-continuum.
>>
> Only if the set is unbounded.
>
=)
Gruff
hurting and Godel's Incompleteness Theorem seems to be warning me
something about maths. I prefer physics.