[Kabar-indonesia] 1 of 2: New Yorker: Two Critiques of String Theory.[+Woody Allen Strung Out]

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-1 of 2- 

[2 of 2: Strung Out: Woody Allen contemplates string
theory]

The New Yorker Magazine 
Issue cover dated October 2, 2006

UNSTRUNG 

In string theory, beauty is truth, truth beauty. Is
that really all we need to know? 

by JIM HOLT 

It is the best of times in physics. Physicists are on
the verge of obtaining the long-sought Theory of
Everything. In a few elegant equations, perhaps
concise enough to be emblazoned on a T-shirt, this
theory will reveal how the universe began and how it
will end. The key insight is that the smallest
constituents of the world are not particles, as had
been supposed since ancient times, but "strings"—tiny
strands of energy. By vibrating in different ways,
these strings produce the essential phenomena of
nature, the way violin strings produce musical notes.
String theory isn't just powerful; it's also
mathematically beautiful. All that remains to be done
is to write down the actual equations. This is taking
a little longer than expected. But, with almost the
entire theoretical-physics community working on the
problem—presided over by a sage in Princeton, New
Jersey—the millennia-old dream of a final theory is
sure to be realized before long.

It is the worst of times in physics. For more than a
generation, physicists have been chasing a
will-o'-the-wisp called string theory. The beginning
of this chase marked the end of what had been
three-quarters of a century of progress. Dozens of
string-theory conferences have been held, hundreds of
new Ph.D.s have been minted, and thousands of papers
have been written. Yet, for all this activity, not a
single new testable prediction has been made, not a
single theoretical puzzle has been solved. In fact,
there is no theory so far—just a set of hunches and
calculations suggesting that a theory might exist.
And, even if it does, this theory will come in such a
bewildering number of versions that it will be of no
practical use: a Theory of Nothing. Yet the physics
establishment promotes string theory with irrational
fervor, ruthlessly weeding dissenting physicists from
the profession. Meanwhile, physics is stuck in a
paradigm doomed to barrenness.

So which is it: the best of times or the worst of
times? This is, after all, theoretical physics, not a
Victorian novel. If you are a casual reader of science
articles in the newspaper, you are probably more
familiar with the optimistic view. But string theory
has always had a few vocal skeptics. Almost two
decades ago, Richard Feynman dismissed it as "crazy,"
"nonsense," and "the wrong direction" for physics.
Sheldon Glashow, who won a Nobel Prize for making one
of the last great advances in physics before the
beginning of the string-theory era, has likened string
theory to a "new version of medieval theology," and
campaigned to keep string theorists out of his own
department at Harvard. (He failed.)

Now two members of the string-theory generation have
come forward with exposés of what they deem to be the
current mess. "The story I will tell could be read by
some as a tragedy," Lee Smolin writes in "The Trouble
with Physics: The Rise of String Theory, the Fall of a
Science, and What Comes Next" (Houghton Mifflin; $26).
Peter Woit, in "Not Even Wrong: The Failure of String
Theory and the Search for Unity in Physical Law"
(Basic; $26.95), prefers the term "disaster." Both
Smolin and Woit were journeyman physicists when string
theory became fashionable, in the early
nineteen-eighties. Both are now outsiders: Smolin, a
reformed string theorist (he wrote eighteen papers on
the subject), has helped found a sort of Menshevik
cell of physicists in Canada called the Perimeter
Institute; Woit abandoned professional physics for
mathematics (he is a lecturer in the mathematics
department at Columbia), which gives him a
cross-disciplinary perspective. Each author delivers a
bill of indictment that is a mixture of science,
philosophy, aesthetics, and, surprisingly, sociology.
Physics, in their view, has been overtaken by a
cutthroat culture that rewards technicians who work on
officially sanctioned problems and discourages
visionaries in the mold of Albert Einstein. Woit
argues that string theory's lack of rigor has left its
practitioners unable to distinguish between a
scientific hoax and a genuine contribution. Smolin
adds a moral dimension to his plaint, linking string
theory to the physics profession's "blatant prejudice"
against women and blacks. Pondering the cult of empty
mathematical virtuosity, he asks, "How many leading
theoretical physicists were once insecure, small,
pimply boys who got their revenge besting the jocks
(who got the girls) in the one place they could—math
class?"

It is strange to think that such sordid motives might
affect something as pure and objective as physics. But
these are strange days in the discipline. For the
first time in its history, theory has caught up with
experiment. In the absence of new data, physicists
must steer by something other than hard empirical
evidence in their quest for a final theory. And that
something they call "beauty." But in physics, as in
the rest of life, beauty can be a slippery thing.

The gold standard for beauty in physics is Albert
Einstein's theory of general relativity. What makes it
beautiful? First, there is its simplicity. In a single
equation, it explains the force of gravity as a
curving in the geometry of space-time caused by the
presence of mass: mass tells space-time how to curve,
space-time tells mass how to move. Then, there is its
surprise: who would have imagined that this whole
theory would flow from the natural assumption that all
frames of reference are equal, that the laws of
physics should not change when you hop on a
merry-go-round? Finally, there is its aura of
inevitability. Nothing about it can be modified
without destroying its logical structure. The
physicist Steven Weinberg has compared it to Raphael's
"Holy Family," in which every figure on the canvas is
perfectly placed and there is nothing you would have
wanted the artist to do differently.

Einstein's general relativity was one of two
revolutionary innovations in the early part of the
twentieth century which inaugurated the modern era in
physics. The other was quantum mechanics. Of the two,
quantum mechanics was the more radical departure from
the old Newtonian physics. Unlike general relativity,
which dealt with well-defined objects existing in a
smooth (albeit curved) space-time geometry, quantum
mechanics described a random, choppy microworld where
change happens in leaps, where particles act like
waves (and vice versa), and where uncertainty reigns.

In the decades after this dual revolution, most of the
action was on the quantum side. In addition to
gravity, there are three basic forces that govern
nature: electromagnetism, the "strong" force (which
holds the nucleus of an atom together), and the "weak"
force (which causes radioactive decay). Eventually,
physicists managed to incorporate all three into the
framework of quantum mechanics, creating the "standard
model" of particle physics. The standard model is
something of a stick-and-bubble-gum contraption: it
clumsily joins very dissimilar kinds of interactions,
and its equations contain about twenty
arbitrary-seeming numbers—corresponding to the masses
of the various particles, the ratios of the force
strengths, and so on—that had to be experimentally
measured and put in "by hand." Still, the standard
model has proved to be splendidly useful, predicting
the result of every subsequent experiment in particle
physics with exquisite accuracy, often down to the
eleventh decimal place. As Feynman once observed,
that's like calculating the distance from Los Angeles
to New York to within a hairbreadth.

The standard model was hammered out by the
mid-nineteen-seventies, and has not had to be
seriously revised since. It tells how nature behaves
on the scale of molecules, atoms, electrons, and on
down, where the force of gravity is weak enough to be
overlooked. General relativity tells how nature
behaves on the scale of apples, planets, galaxies, and
on up, where quantum uncertainties average out and can
be ignored. Between the two theories, all nature seems
to be covered. But most physicists aren't happy with
this division of labor. Everything in nature, after
all, interacts with everything else. Shouldn't there
be a single set of rules for describing it, rather
than two inconsistent sets? And what happens when the
domains of the two theories overlap—that is, when the
very massive is also the very small? Just after the
big bang, for example, the entire mass of what is now
the observable universe was packed into a volume the
size of an atom. At that tiny scale, quantum
uncertainty causes the smooth geometry of general
relativity to break up, and there is no telling how
gravity will behave. To understand the birth of the
universe, we need a theory that "unifies" general
relativity and quantum mechanics. That is the
theoretical physicist's dream.

String theory came into existence by accident. In the
late nineteen-sixties, a couple of young physicists
thumbing through mathematics books came upon a
centuries-old formula that, miraculously, seemed to
fit the latest experimental data about elementary
particles. At first, no one had a clue why this should
be. Within a few years, however, the hidden meaning of
the formula emerged: if elementary particles were
thought of as tiny wriggling strings, it all made
sense. What were these strings supposed to be made of?
Nothing, really. As one physicist put it, they were to
be thought of as "tiny one-dimensional rips in the
smooth fabric of space."

This wasn't the only way in which the new theory broke
with previous thinking. We seem to live in a world
that has three spatial dimensions (along with one time
dimension). But for string theory to make mathematical
sense the world must have nine spatial dimensions. Why
don't we notice the six extra dimensions? Because,
according to string theory, they are curled up into
some microgeometry that makes them invisible. (Think
of a garden hose: from a distance it looks
one-dimensional, like a line; up close, however, it
can be seen to have a second dimension, curled up into
a little circle.) The assumption of hidden dimensions
struck some physicists as extravagant. To others,
though, it seemed a small price to pay. In Smolin's
words, "String theory promised what no other theory
had before—a quantum theory of gravity that is also a
genuine unification of forces and matter."

But when would it make good on that promise? In the
decades since its possibilities were first glimpsed,
string theory has been through a couple of
"revolutions." The first took place in 1984, when some
potentially fatal kinks in the theory were worked out.
On the heels of this achievement, four physicists at
Princeton, dubbed the Princeton String Quartet, showed
that string theory could indeed encompass all the
forces of nature. Within a few years, physicists
around the world had written more than a thousand
papers on string theory. The theory also attracted the
interest of the leading figure in the world of
theoretical physics, Edward Witten.

Witten, now at the Institute for Advanced Study, in
Princeton, is held in awe by his fellow-physicists,
who have been known to compare him to Einstein. As a
teen-ager, he was more interested in politics than in
physics. In 1968, at the age of seventeen, he
published an article in The Nation arguing that the
New Left had no political strategy. He majored in
history at Brandeis, and worked on George McGovern's
1972 Presidential campaign. (McGovern wrote him a
letter of recommendation for graduate school.) When he
decided to pursue a career in physics, he proved to be
a quick study: Princeton Ph.D., Harvard postdoc, full
professorship at Princeton at the age of twenty-nine,
MacArthur "genius grant" two years later. Witten's
papers are models of depth and clarity. Other
physicists attack problems by doing complicated
calculations; he solves them by reasoning from first
principles. Witten once said that "the greatest
intellectual thrill of my life" was learning that
string theory could encompass both gravity and quantum
mechanics. His string-theoretic investigations have
led to stunning advances in pure mathematics,
especially in the abstract study of knots. In 1990, he
became the first physicist to be awarded the Fields
Medal, considered the Nobel Prize of mathematics.

It was Witten who ushered in the second string-theory
revolution, which addressed a conundrum that had
arisen, in part, from all those extra dimensions. They
had to be curled up so that they were invisibly small,
but it turned out that there were various ways of
doing this, and physicists were continually finding
new ones. If there was more than one version of string
theory, how could we decide which version was correct?
No experiment could resolve the matter, since string
theory concerns energies far beyond those which can be
attained by particle accelerators. By the early
nineteen-nineties, no fewer than five versions of
string theory had been devised. Discouragement was in
the air. But the mood improved markedly when, in 1995,
Witten announced to an audience of string theorists at
a conference in Los Angeles that these five seemingly
distinct theories were mere facets of something
deeper, which he called "M-theory." In addition to
vibrating strings, M-theory allowed for vibrating
membranes and blobs. As for the name of the new
theory, Witten was noncommittal; he said that "M
stands for magic, mystery, or membrane, according to
taste." Later, he mentioned "murky" as a possibility,
since "our understanding of the theory is, in fact, so
primitive." Other physicists have suggested "matrix,"
"mother" (as in "mother of all theories"), and
"masturbation." The skeptical Sheldon Glashow wondered
whether the "M" wasn't an upside-down "W," for Witten.

Today, more than a decade after the second revolution,
the theory formerly known as strings remains a
seductive conjecture rather than an actual set of
equations, and the non-uniqueness problem has grown to
ridiculous proportions. At the latest count, the
number of string theories is estimated to be something
like one followed by five hundred zeros. "Why not just
take this situation as a reductio ad absurdum?" Smolin
asks. But some string theorists are unabashed: each
member of this vast ensemble of alternative theories,
they observe, describes a different possible universe,
one with its own "local weather" and history. What if
all these possible universes actually exist? Perhaps
every one of them bubbled into being just as our
universe did. (Physicists who believe in such a
"multiverse" sometimes picture it as a cosmic
champagne glass frothing with universe-bubbles.) Most
of these universes will not be biofriendly, but a few
will have precisely the right conditions for the
emergence of intelligent life-forms like us. The fact
that our universe appears to be fine-tuned to engender
life is not a matter of luck. Rather, it is a
consequence of the "anthropic principle": if our
universe weren't the way it is, we wouldn't be here to
observe it. Partisans of the anthropic principle say
that it can be used to weed out all the versions of
string theory that are incompatible with our
existence, and so rescue string theory from the
problem of non-uniqueness.

Copernicus may have dislodged man from the center of
the universe, but the anthropic principle seems to
restore him to that privileged position. Many
physicists despise it; one has depicted it as a
"virus" infecting the minds of his fellow-theorists.
Others, including Witten, accept the anthropic
principle, but provisionally and in a spirit of gloom.
Still others seem to take perverse pleasure in it. The
controversy among these factions has been likened by
one participant to "a high-school-cafeteria food
fight."

In their books against string theory, Smolin and Woit
view the anthropic approach as a betrayal of science.
Both agree with Karl Popper's dictum that if a theory
is to be scientific it must be open to falsification.
But string theory, Woit points out, is like Alice's
Restaurant, where, as Arlo Guthrie's song had it, "you
can get anything you want." It comes in so many
versions that it predicts anything and everything. In
that sense, string theory is, in the words of Woit's
title, "not even wrong." Supporters of the anthropic
principle, for their part, rail against the
"Popperazzi" and insist that it would be silly for
physicists to reject string theory because of what
some philosopher said that science should be. Steven
Weinberg, who has a good claim to be the father of the
standard model of particle physics, has argued that
anthropic reasoning may open a new epoch. "Most
advances in the history of science have been marked by
discoveries about nature," he recently observed, "but
at certain turning points we have made discoveries
about science itself."

Is physics, then, going postmodern? (At Harvard, as
Smolin notes, the string-theory seminar was for a time
actually called "Postmodern Physics.") The modern era
of particle physics was empirical; theory developed in
concert with experiment. The standard model may be
ugly, but it works, so presumably it is at least an
approximation of the truth. In the postmodern era, we
are told, aesthetics must take over where experiment
leaves off. Since string theory does not deign to be
tested directly, its beauty must be the warrant of its
truth.

In the past century, physicists who have followed
their aesthetic sense in the absence of experimental
data seem to have done quite well. As Paul Dirac said,
"Anyone who appreciates the fundamental harmony
connecting the way Nature runs and general
mathematical principles must feel that a theory with
the beauty and elegance of Einstein's theory has to be
substantially correct." The idea that "beauty is
truth, truth beauty" may be a beautiful one, but is
there any reason to think it is true? Truth, after
all, is a relationship between a theory and the world,
whereas beauty is a relationship between a theory and
the mind. Perhaps, some have conjectured, a kind of
cultural Darwinism has drilled it into us to take
aesthetic pleasure in theories that are more likely to
be true. Or perhaps physicists are somehow inclined to
choose problems that have beautiful solutions rather
than messy ones. Or perhaps nature itself, at its most
fundamental level, possesses an abstract beauty that a
true theory is bound to mirror. What makes all these
explanations suspect is that standards of theoretical
beauty tend to be ephemeral, routinely getting
overthrown in scientific revolutions. "Every property
that has at some date been seen as aesthetically
attractive in theories has at other times been judged
as displeasing or aesthetically neutral," James W.
McAllister, a philosopher of science, has observed.

The closest thing to an enduring mark of beauty is
simplicity; Pythagoras and Euclid prized it, and
contemporary physicists continue to pay lip service to
it. All else being equal, the fewer the equations, the
greater the elegance. And how does string theory do by
this criterion? Pretty darn well, one of its partisans
has facetiously observed, since the number of defining
equations it has so far produced remains precisely
zero. At first, string theory seemed the very Tao of
simplicity, reducing all known particles and forces to
the notes of a vibrating string. As one of its
pioneers commented, "String theory was too beautiful a
mathematical structure to be completely irrelevant to
nature." Over the years, though, it has repeatedly had
to be jury-rigged in the face of new difficulties, so
that it has become a Rube Goldberg machine—or, rather,
a vast landscape of them. Its proponents now inveigh
against what they call "the myth of uniqueness and
elegance." Nature is not simple, they maintain, nor
should our ultimate theory of it be. "A good, honest
look at the real world does not suggest a pattern of
mathematical minimality," says the Stanford physicist
Leonard Susskind, who seems to have no regrets about
string theory's having "gone from being Beauty to the
Beast."

If neither predictive value nor beauty explains the
persistence of string theory, then what does? Since
the late eighteenth century, no major scientific
theory has been around for more than a decade without
getting a thumbs-up or a thumbs-down. Correct theories
nearly always triumph quickly. But string theory, in
one form or another, has been hanging on
inconclusively for more than thirty-five years.
Einstein's own pursuit of a unified theory of physics
in the last three decades of his life is often cited
as a case study in futility. Have a thousand string
theorists done any better?

The usual excuse offered for sticking with what
increasingly looks like a failed program is that no
one has come up with any better ideas for unifying
physics. But Smolin and Woit have a different
explanation, one that can be summed up in the word
"sociology." Both are worried that academic physics
has become dangerously like what the social
constructivists have long charged it with being: a
community that is no more rational or objective than
any other group of humans. String theorists dominate
the country's top physics departments. At the
Institute for Advanced Study, the director and nearly
all of the particle physicists with permanent
positions are string theorists. Eight of the nine
MacArthur fellowships awarded to particle physicists
over the years have gone to string theorists. Since
the fall-off in academic hiring in the
nineteen-seventies, the average age of tenured physics
professors has reached nearly sixty. Every year,
around eighty people receive Ph.D.s in particle
physics, but only around ten of them can expect to get
permanent jobs in the field. In this hypercompetitive
environment, the only hope for a young theoretical
physicist is to curry favor by solving a set problem
in string theory. "Nowadays," one established figure
in the field has said, "if you're a hot-shot young
string theorist you've got it made."

Both authors also detect a cultlike aspect to the
string-theory community, with Witten as the guru.
Perhaps, it has been joked, physicists might have an
easier time getting funding from the Bush
Administration if they represented string theory as a
"faith-based initiative." Smolin deplores what he
considers to be the shoddy scientific standards that
prevail in the string-theory community, where
long-standing but unproved conjectures are assumed to
be true because "no sensible person"—that is, no
member of the tribe—doubts them. The most hilarious
recent symptom of string theory's lack of rigor is the
so-called Bogdanov Affair, in which French twin
brothers, Igor and Grichka Bogdanov, managed to
publish egregiously nonsensical articles on string
theory in five peer-reviewed physics journals. Was it
a reverse Sokal hoax? (In 1996, the physicist Alan
Sokal fooled the editors of the postmodern journal
Social Text into publishing an artful bit of drivel on
the "hermeneutics of quantum gravity.") The Bogdanov
brothers have indignantly denied it, but even the
Harvard string-theory group was said to be unsure,
alternating between laughter at the obviousness of the
fraud and hesitant concession that the authors might
have been sincere.

These two books present the case against string theory
with wit and conviction, though Smolin's book is by
far the more lucid and accessible. Woit has too many
pages full of indigestible sentences like "The Hilbert
space of the Wess-Zumino-Witten model is a
representation not only of the Kac-Moody group, but of
the group of conformal transformations as well."
(Distressingly, he goes on to confess that this is "a
serious oversimplification.") Let's assume that the
situation in theoretical physics is as bad as Smolin
and Woit say it is. What are non-physicists supposed
to do about it? Should we form a sort of children's
crusade to capture the holy land of physics from the
string-theory usurpers? And whom should we install in
their place?

Smolin furnishes the more definite answer. The current
problem with physics, he thinks, is basically a
problem of style. The initiators of the dual
revolution a century ago—Einstein, Bohr, Schrödinger,
Heisenberg—were deep thinkers, or "seers." They
confronted questions about space, time, and matter in
a philosophical way. The new theories they created
were essentially correct. But, Smolin writes, "the
development of these theories required a lot of hard
technical work, and so for several generations physics
was 'normal science' and was dominated by master
craftspeople." Today, the challenge of unifying those
theories will require another revolution, one that
mere virtuoso calculators are ill-equipped to carry
out. "The paradoxical situation of string theory—so
much promise, so little fulfillment—is exactly what
you get when a lot of highly trained master
craftspeople try to do the work of seers," Smolin
writes.

The solution is to cultivate a new generation of
seers. And what, really, is standing in the way of
that? Einstein, after all, didn't need to be nurtured
by the physics establishment, and Smolin gives many
examples of outsider physicists in the style of
Einstein, including one who spent ten years in a rural
farmhouse successfully reinterpreting general
relativity. Neither Smolin nor Woit calls for the
forcible suppression of string theory. They simply ask
for a little more diversity. "We are talking about
perhaps two dozen theorists," Smolin says. This is an
exceedingly modest request, for theoretical physics is
the cheapest of endeavors. Its practitioners require
no expensive equipment. All they need is legal pads
and pencils and blackboards and chalk to ply their
trade, plus room and board and health insurance and a
place to park their bikes. Intellectually daunting as
the crisis in physics may be, its practical solution
would seem to demand little more than the annual
interest on the rounding error of a Google founder's
fortune.

"How strange it would be if the final theory were to
be discovered in our own lifetimes!" Steven Weinberg
wrote some years ago, adding that such a discovery
would mark the sharpest discontinuity in intellectual
history since the beginning of modern science, in the
seventeenth century. Of course, it is possible that a
final theory will never be found, that neither string
theory nor any of the alternatives mentioned by Smolin
and Woit will come to anything. Perhaps the most
fundamental truth about nature is simply beyond the
human intellect, the way that quantum mechanics is
beyond the intellect of a dog. Or perhaps, as Karl
Popper believed, there will prove to be no end to the
succession of deeper and deeper theories. And, even if
a final theory is found, it will leave the questions
about nature that most concern us—how the brain gives
rise to consciousness, how we are constituted by our
genes—untouched. Theoretical physics will be finished,
but the rest of science will hardly notice.

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