'Theory of everything' tying researchers up in knots
George
The most celebrated theory in modern physics faces increasing attacks from
skeptics who fear it has lured a generation of researchers down an intellectual
dead end.
In its original, simplified form, circa the mid-1980s, string theory held that
reality consists of infinitesimally small, wiggling objects called strings,
which vibrate in ways that yield the different subatomic particles that comprise
the cosmos. An analogy is the vibrations on a violin string, which yield
different musical notes.
Advocates claimed that string theory would smooth out the conflicts between
Einsteinian relativity and quantum mechanics. The result, they said, would be a
grand unifying "theory of everything," which could explain everything from the
nature of matter to the Big Bang to the fate of the cosmos.
Over the years, string theory has simultaneously become more frustrating and
fabulous. On the one hand, the original theory has become mind-bogglingly
complex, one that posits an 11-dimensional universe (far more than the four-
dimensional universe of Einstein). The modified theory is so mathematically
dense that many Ph.D.-bearing physicists haven't a clue what their string-
theorist colleagues are talking about.
On the other hand, new versions of the theory suggest our universe is just one
of zillions of alternate, invisible -- perhaps even inhabited -- universes where
the laws of physics are radically different. String buffs claim this bizarre
hypothesis might help to explain various cosmic mysteries.
Untestable theory
But skeptics suggest it's the latest sign of how string theorists, sometimes
called "superstringers," try to colorfully camouflage the theory's flaws, like
"a 50-year-old woman wearing way too much lipstick," jokes Robert B. Laughlin, a
Nobel Prize-winning physicist at Stanford. "People have been changing string
theory in wild ways because it has never worked."
Already, the split over string theory has caused tensions at some of the
nation's university physics departments. "The physics department at Stanford
effectively fissioned over this issue," said Laughlin, now on sabbatical in
South Korea. "I think string theory is textbook 'post-modernism' (and) fueled by
irresponsible expenditures of money."
The dispute could become explosive this year, with the publication of contrarily
minded books by two of the best-known and most eloquent scientific popularizers
of physics, string theorist Michio Kaku of City University of New York and
astrophysicist-particle theorist Lawrence Krauss of Case Western Reserve
University in Cleveland.
Skeptics have long mocked string theory as untestable, because experimental
studies of it would require machines of huge scale, perhaps even as big as the
solar system. In his new book "Parallel Worlds" (Doubleday), Kaku disagrees and
argues that the first experimental evidence for string theory might begin to
emerge within several years from experiments with scientific instruments such as
a new particle accelerator, the Large Hadron Collider, which opens for business
near Geneva in 2007.
Wormhole travel
Kaku, whose previous books include the acclaimed "Hyperspace" and
equation-packed textbooks on string theory, also suggests that humans might
eventually travel to those alternate universes, perhaps via hypothetical portals
in space called wormholes.
Such claims dismay Krauss, a leading expert on cosmic dark matter and dark
energy who is popularly known as author of a best-seller, "The Physics of Star
Trek." In his book "Hiding in the Mirror: The Mysterious Allure of Extra
Dimensions," to be published by Viking in September, Krauss argues that string
theorists have produced no satisfactory explanations for anything.
Krauss believes continued research is worthwhile just in case it pans out. But
he said that so far, string theorists have promised far more than they have
delivered and have fostered the false impression that string theory is the only
feasible way to explain cosmic mysteries.
Those who dabble in alternate-universe speculations might be just modern
versions of "16th century theologians (who) speculated that spirits and angels
emerge from the extra-dimensional universe," says Krauss, who is also an
outspoken foe of creationist teaching in schools.
A great deal is at stake. Over the last two decades, a generation of brilliant
young physicists -- the kinds of proto-Einsteins who historically have led
intellectual revolution after revolution -- has flocked to string theory because
their professors told them that's where the action was. Now many of them are
reaching middle age and have gained tenured posts on prestigious campuses.
They're also educating a whole new generation of fresh- faced wannabe string
theorists who are thrilled by the publicity that string theory attracts, which
has included several best-selling books and a special effects-packed TV
extravaganza on PBS.
The dispute has split partly along subdisciplinary lines, and mirrors a timeless
squabble in the philosophy of science: Which is more important for scientific
innovation -- theoretical daring or empirical observations and experiments?
"Superstringers have now created a culture in physics departments that is openly
disdainful of experiments. ... There is an intellectual struggle going on for
the very soul of theoretical physics, and for the hearts and minds of young
scientists entering our field," says physicist Zlatko Tesanovic of Johns Hopkins
University.
String theorists and their foes can't even agree on what constitutes success or
failure. For example, the most unexpected and counterintuitive discovery of
recent science occurred in the 1990s, when astrophysicists at Berkeley and
elsewhere realized the universe is expanding faster with time. The apparent
reason: a mysterious dark energy pervades space and drives the accelerated
expansion.
Critics mock superstringers because their so-called theory of everything failed
to predict this colossal discovery. String theorists fire back that no one else
predicted it, either, and besides, "string theory is the only approach that has
the potential for explaining dark energy" based on pure theory, says John
Schwarz, a pioneering string theorist at Caltech.
That's because string theory is the only existing hypothesis that holds serious
promise of merging the two grandest branches of physics -- the theory of
gravity, the basis of cosmological theory; and quantum mechanics, the science of
the subatomic realm, Schwarz says.
Even so, "it's my impression that more and more physicists are starting to join
Krauss as 'skeptical agnostics' about string theory," said mathematician Peter
Woit of Columbia University, who offers comments on string- theory developments
at his blog: www.math.columbia.edu/~woit/blog/.
One possible reason for the sea change is that string theory's ambitions have
radically changed since the 1980s. Back then, theorists hoped to develop a
string theory that would predict the existence of one universe -- ours, of
course -- with its given physical forces and constants, such as the known
intensity of gravity and the known electrical charge on the electron.
In later years, though, string theorists realized their theory predicted
innumerable possible universes with widely varying physical forces and
constants. As usual, superstringers and their critics viewed this development
differently.
To critics, like Woit, it is a disaster for string theory because the sheer
number of estimated universes -- equal to the number one followed by 500
zeroes -- is unimaginably large.
If true, it means that string theory is so flexible that it can be used to
predict almost any kind of universe you want, no matter how crazy, and hence it
predicts nothing specific enough to be scientifically interesting.
"A theory that can't predict anything is not a scientific theory," Woit says.
But what if the universe is unimaginably complex and as jammed with diverse
universes as the seas are jammed with diverse fish? That's the thesis of Kaku,
who compares the history of string research to "wandering around the desert and
then stumbling on a tiny pebble. But when we examine it carefully, we find that
it's actually the tip of a gigantic pyramid."
"But just as we are about to open the door," Kaku says, "some critics say that
it's taking too much time, that the writings are too hard to understand, that
(it) is draining resources from other projects, that it's getting too much
publicity, that the script seems to be mutating as we go from floor to floor, et
cetera, et cetera."
Opinions on the theory
In an informal Chronicle e-mail survey, the world's physicists expressed widely
differing, sometimes emotional, opinions on the dispute over string theory:
-- "String theory is anything but a futile effort," said an e-mail from David
Gross of UC Santa Barbara, who shared the Nobel Prize in physics last year.
Among other accomplishments, it has enabled physicists "to understand, finally,
many of the mysteries of black holes. ... I am convinced that string theory, as
presently understood, is on the right path, but that this path is quite long,
and (perhaps many) further breakthroughs are required."
-- "I agree entirely with Larry Krauss," says Nobel Prize-winning physicist
Philip Anderson of Princeton University. In academia, "we from outside the
(string) field are disturbed by our colleagues' insistence that every new
semi-adolescent who has done something in string theory is the greatest genius
since Einstein and therefore must occupy yet another tenure track. ... Our
sciences are becoming increasingly infected with quasi-theology, a tendency
which needs to be openly debated."
-- "To the considerable extent that string theory has been developed, it has
turned out to be a logically consistent quantum theory of gravity," says string
theorist Raphael Bousso of Lawrence Berkeley National Laboratory. "This is a
very significant achievement utterly unmatched by any other approach to this
problem -- and many have been tried over the past several decades."
-- "There has been, in recent years, a pernicious, uncritical hype of string
theory," says Carlo Rovelli of the Centre de Physique Theorique in Marseille,
France. While the theory is worth developing and is a "very interesting attempt
to address the fundamental open problems of physics," he says, "so far it is
only an attempt, (one) that has delivered less than what was expected some years
ago," and "its uncritical promotion is damaging to science."
-- Krauss' charge that string theory "has probably been the least successful
'great' idea in physics" in a century is unfair and premature, replies string
physicist Brian Greene of Columbia University, author of two acclaimed books on
the topic, including "The Elegant Universe." "That's like someone going into
Antonio Stradivari's workshop and complaining about the sound produced by one of
his as yet unfinished violins."
Mysterious Wayz
>
> [snip]
> Krauss' charge that string theory "has probably been the least successful
> 'great' idea in physics" in a century is unfair and premature, replies string
> physicist Brian Greene of Columbia University, author of two acclaimed books on
> the topic, including "The Elegant Universe." "That's like someone going into
> Antonio Stradivari's workshop and complaining about the sound produced by one of
> his as yet unfinished violins."
It's got to be good for a few hundred more grants anyway. Perhaps it could be
rolled into astronomy somehow.
--
If I knew I wuz going to liv this long,
I would've taken better care of myself.
Nivlem
<geo...@wtfiswrongwithyou.com> wrote:
>http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2005/03/14/MNGRMBOURE1.DTL
>The most celebrated theory in modern physics faces increasing attacks from
>skeptics who fear it has lured a generation of researchers down an intellectual
>dead end.
>
<snip rest for brevity>
I must advance my own criticism here, founded though it
probably is on utter ignorance. The attraction of string
theory is said to be partly it's mathematical elegance. I
must observe, though, that one can do the most lovely
equations, and yet everything on the right side of the " ="
sums to zero. I also do not like that it relies upon totally
undetectable "somethings". It appears to share this quality
with such discredited notions as the ether.
George
"Nivlem" <ml...@svn.net> wrote in message
news:ckme311om7ldr7jcb...@4ax.com...
The worst part of it is that it can't be verified by experimentation and direct
observation.
John
"George" <geo...@wtfiswrongwithyou.com> wrote in message
news:muKZd.135518$4q6.26189@attbi_s01...
Yet. That's the problem... the only predictions it can make involve
quantities so small they are impossible to accurately measure at this point.
Nivlem
I'd even settle for some sort of indirect observation. A
behavior of subatomic particles that could only result from
the existence of strings, say. What we appear to have
instead is mathematical models of the limits of the
imaginations of some of the brightest minds of a generation.
Unlike the ether I mentioned previously, string theory is
apparently unfalsifiable. This leads me to suspect this
theory is in the category of worthless speculation known as
metaphysics. All that noise about other universes, for
example. As I understand it, the universe encompasses
everything known to exist. By definition, we can have no
information about alternate universes in our universe,
anymore than we can know what came before the Big Bang. How
can branes and alternate universes be considered science?
George
"I don't know, man. They tell me to fix the transporter, so that's what I do."
lol
Nathan Urban
> Unlike the ether I mentioned previously, string theory is apparently
> unfalsifiable.
String theory is falsifiable in principle, but we don't know if we can
construct experiments that are capable of falsifying it in practice.
In some string scenarios, we can; in others, possibly not.
> This leads me to suspect this theory is in the category of worthless
> speculation known as metaphysics. All that noise about other
> universes, for example.
Some string scenarios have "other universes", and some don't.
> As I understand it, the universe encompasses everything known to exist.
That's a vague definition. Do you mean to imply the observable
universe? What about parts of spacetime outside of our cosmological
horizon, or within a black hole's event horizon? Technically we don't
"know" what, if anything, exists beyond a horizon.
> By definition, we can have no information about alternate universes
> in our universe,
Well, yes, if you want to use that definition... but if you want to
use that definition, there are no "alternate universes" in string
theory. e.g., in the braneworld scenarios with multiple branes, the
branes other than ours *can* interact with ours (gravitationally).
Then according to your definition, the branes are not "alternate
universes". So what are you complaining about?
> anymore than we can know what came before the Big Bang.
If something came before the Big Bang, we might be able to know what
came before it; there could be observable consequences for our
universe. We don't know; our theories of the Big Bang are not great
right now.
> How can branes and alternate universes be considered science?
They make physical predictions which can in principle be tested by
experiment, like any other science.
George
"Nathan Urban" <nur...@crib.corepower.com> wrote in message
news:d18a4j$489h$1...@news3.infoave.net...
Hmmm. In principle? Then why isn't anyone testing them?
Nivlem
nur...@crib.corepower.com (Nathan Urban) wrote:
>In article <2v7f31p50rp1i3o66...@4ax.com>, Nivlem <ml...@svn.net> wrote:
>
>> Unlike the ether I mentioned previously, string theory is apparently
>> unfalsifiable.
>
>String theory is falsifiable in principle, but we don't know if we can
>construct experiments that are capable of falsifying it in practice.
>In some string scenarios, we can; in others, possibly not.
>
If you can't falsify it in practice, you can't falsify it.
>> This leads me to suspect this theory is in the category of worthless
>> speculation known as metaphysics. All that noise about other
>> universes, for example.
>
>Some string scenarios have "other universes", and some don't.
>
OK. I didn't claim to be expert in this area.
>> As I understand it, the universe encompasses everything known to exist.
>
>That's a vague definition. Do you mean to imply the observable
>universe? What about parts of spacetime outside of our cosmological
>horizon, or within a black hole's event horizon? Technically we don't
>"know" what, if anything, exists beyond a horizon.
>
I'm not sure how to define it more precisely. If there's a
definition you like, state it and we'll work with that.
>> By definition, we can have no information about alternate universes
>> in our universe,
>
>Well, yes, if you want to use that definition... but if you want to
>use that definition, there are no "alternate universes" in string
>theory. e.g., in the braneworld scenarios with multiple branes, the
>branes other than ours *can* interact with ours (gravitationally).
>Then according to your definition, the branes are not "alternate
>universes". So what are you complaining about?
>
So where's the evidence that they do?
>> anymore than we can know what came before the Big Bang.
>
>If something came before the Big Bang, we might be able to know what
>came before it; there could be observable consequences for our
>universe. We don't know; our theories of the Big Bang are not great
>right now.
>
How would one get any information about a prior state of
the universe, once everything's been compressed to the
degree that it would have been just prior to the Big Bang?
How would you not just have undifferentiated, super-dense
stuff?
J. J. Lodder
> On Mon, 14 Mar 2005 23:41:58 GMT, "George"
> <geo...@wtfiswrongwithyou.com> wrote:
>
> >http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2005/03/14/MNGRMBOURE1.DTL
> >The most celebrated theory in modern physics faces increasing attacks
> >from skeptics who fear it has lured a generation of researchers down an
> >intellectu al dead end.
You never know which ends are dead
until you have found one that isn't.
> <snip rest for brevity>
>
> I must advance my own criticism here, founded though it
> probably is on utter ignorance. The attraction of string
> theory is said to be partly it's mathematical elegance. I
> must observe, though, that one can do the most lovely
> equations, and yet everything on the right side of the " ="
> sums to zero. I also do not like that it relies upon totally
> undetectable "somethings". It appears to share this quality
> with such discredited notions as the ether.
And with things called 'wavefunctions' and 'quarks'.
And only a century ago Mach criticized his theoretical collegues
for using 'totally undetectable "somethings"'
called 'atoms' or 'molecules' in their theories.
There is nothing wrong with using undetectables,
or even undetectables in principle. (like quarks)
What's wrong is not making any observable predictions,
and even failure to retrodict what is already known.
Best,
Jan
--
"Aber haben Sie eine gesehen?"
"But have you seen one?" (Ernst Mach)
Zachriel
That has not been demonstrated.
> This leads me to suspect this
> theory is in the category of worthless speculation known as
> metaphysics.
Perhaps. Let me bring out my old saw about the scientific method:
hypothesis, prediction, observation, validation, repeat. Now there is
nothing there about how long it takes to develop an hypothesis, or when a
valid prediction needs to be made. The time between Einstein's proposed
General Theory of Relativity to validated observations was several years,
and can still be considered to be under scrutiny even now. The theory was
always science though, as it could be tested in principle, and was
eventually tested.
> All that noise about other universes, for
> example. As I understand it, the universe encompasses
> everything known to exist. By definition, we can have no
> information about alternate universes in our universe,
That's just semantics. I prefer the term "local universe", "regional
universe" or "visible universe", but the nomenclature is apparently heading
towards multiverses.
Nivlem
<"http://www.zachriel.com/mutagenation/contact.asp"@giganews.com>
wrote:
As I think I've mentioned, I don't have any expertise. All
I'm going on is a sort of "does what I can find out about
this pass the smell test?" And as I've said, string theory
doesn't. That's been a fairly accurate way of evaluating
things for me in the past. If there ever does come to be
some practical way of testing string theory, my money's on
it flunking out. Should that occur in my lifetime, and I'm
wrong, I suppose I have to lose gracefully.