Text 12976, 148 rader
Skriven 2006-09-18 20:29:10 av Rich Gauszka (1:379/45)
  Kommentar till text 12803 av John Beamish (1:379/45)
Ärende: Re: String theory
=========================
From: "Rich Gauszka" <gauszka@hotmail.com>


"John Beamish" <JLBeamish@rogers.com> wrote in message
news:op.te78jto1m6tn4t@dellblack.wlfdle.phub.net.cable.rogers.com...
> Explained in a flash ... well, actually, explained in a Flash
> presentation.
>
> http://www.tenthdimension.com/flash.php
>
> Or, for the more text-based of us, try here
> http://www.tenthdimension.com/

Just when I thought I understood a bit about String Theory with your posted
link, Slate publishes an article that calls it all claptrap <g>

http://www.slate.com/id/2149598/?nav=ais

It's claptrap, a new book argues.
By Gregg Easterbrook

The leading universities are dominated by hooded monks who speak in
impenetrable mumbo-jumbo; insist on the existence of fantastic mystical forces,
yet can produce no evidence of these forces; and enforce a rigid guild
structure of beliefs in order to maintain their positions and status. The
Middle Ages? No, the current situation in university physics departments. I
just invented the part about the hoods.

The upper rungs of the particle-physics faculties at Princeton, Stanford, and
elsewhere in the academy are today heavy with advocates of "string theory," a
proposed explanation for the existence of the universe. String theory seeks to
explain why, at the very minute scale, matter appears to be constructed from
vibrating nothing. Smash up subatomic particles into smaller units such as
quarks, and the quarks don't appear to have content-puzzling, to say the least.
String theory says that these seemingly amorphous infinitesimal aspects of
matter are made from other dimensions, compressed to a smallness that strains
imagination. In various versions, the theory also seeks to explain how the Big
Bang could have been possible, to reconcile the extremely tiny realm of quantum
mechanics with the cosmic kingdom of general relativity, and to answer whether
the expansion of our universe will stop or continue forever.

Important stuff! But string theory works only if you assume the existence of
other dimensions-nine, 11, or 25 of them, depending on your flavor of string
thinking-and there's not one shred of evidence other dimensions exist. This may
render string theory highfalutin nonsense that has hijacked academic physics.
Such is the thesis of The Trouble With Physics, a compelling new book by Lee
Smolin, among the leading physicists of the day. Smolin's is the most important
book about cosmology since Steven Weinberg's 1977 volume The First Three
Minutes. If you worry that even in the 21st century, intellectual fads have as
much to do with university politics and careerism as with the search for
abstract truth, The Trouble With Physics is a book you absolutely must read.
"String theory now has such a dominant position in the academy that it is
practically career suicide for young theoretical physicists not to join the
field," Smolin writes. Yet since string theory became ascendant about three
decades ago, "there has not been a single genuine breakthrough in understanding
of elementary particle physics." Not only is string theory rife with malarkey
about imperceptible dimensions, Smolin fears, it may be holding back legitimate
science.

Who is Smolin? A former physics instructor at Yale and Penn State, he now works
at this new Canadian think tank, established with seed money from the
entrepreneur behind the BlackBerry. About 15 years ago, Smolin's name became
among the most talked-about in science, for an idea that's a cosmic version of
Darwin. Modern physics is troubled by the anthropocentric character of the
universe. For instance, had gravity been only a teensy bit stronger or weaker,
planets and stars could not have formed. So, does the fortuitous value of
gravity for planets and stars show that a higher power is manipulating physical
law? Some theorists have responded to this quandary by supposing that our
60-billion-galaxy universe is but a slice of a far larger "multiverse" with a
cornucopia of different realities, each operating under its own physics. By
chance one section of the multiverse got physical laws that favor us, and
chance was all that was involved. Smolin countered with his theory of cosmic
natural selection. The theory goes like this: Black holes cause Big Bangs. Any
universe whose physical laws do not result in black holes thus will hit a
cosmic dead end and fail to "reproduce." The set of physical laws that result
in stars and planets also results in black holes, allowing universes like ours
to copy themselves. Over eons, the firmament would become dominated by
universes possessing the kind of laws we observe, because universes with such
laws "reproduce." Therefore it is not weird that our cosmos has stars and
planets; it is exactly what we should expect.

he physics establishment reacted adversely to Smolin's cosmic natural selection
because the idea implies direction: Over time, existence progresses toward a
condition more to the liking of beings such as us. In recent decades it has
become essential at the top of academia to posit utter meaninglessness to all
aspects of physics. Multiverse thinking is as meaningless as it gets-thousands
or billions of universes uninhabitable and pointless, ours just a random-chance
variation signifying nothing. Smolin's idea is full of problems, including the
lack of any evidence that black holes cause Big Bangs. But Smolin could hardly
have failed to note that he was heckled for speculating about conditions for
which there is no evidence while the entire edifice of string theory rests atop
no evidence. The Trouble With Physics is his rejoinder.

String theory became a media obsession about 20 years ago, with one of its
proponents a cover boy of a New York Times Magazine article proclaiming string
theorists were super-ultra geniuses cracking the ultimate riddles of creation.
Smolin's book suggests that this caused string theorists to believe their media
hype and to speak of their concepts as if they were proven. For example, they
talk of "branes" (short for membranes) of limited dimensions passing through
realms of multitudinous dimensions and describe branes as actual physical
regions. Yet after decades of attempts, no experiment has detected any hint of
additional dimensions, branes, or other core elements of string theory.
Meanwhile string theory failed to predict the biggest astrophysical discovery
in decades, the 1998 finding that cosmic expansion is accelerating, apparently
owing to powerful "dark energy" that nobody can explain. After dark energy was
discovered, string theorists simply revised their equations to predict it.
That's not science, The Trouble With Physics contends.

Maybe string theory eventually will prove out; maybe the apparent vibrating
nothing on which we are based is but a slice of some far grander reality. But
string theory seems to contain significant helpings of blather designed to
intimidate nonscientists from questioning the budgets of physics departments
and tax-funded particle accelerator labs. And consider this. Today if a
professor at Princeton claims there are 11 unobservable dimensions about which
he can speak with great confidence despite an utter lack of supporting
evidence, that professor is praised for incredible sophistication. If another
person in the same place asserted there exists one unobservable dimension, the
plane of the spirit, he would be hooted down as a superstitious crank.

Really, string theory isn't a theory at all. Creationists who oppose the
teaching of Darwin have taken to deriding natural selection as "just a theory,"
and Darwin's defenders have rightly replied that in science, "theory" does not
mean idle speculation. Rather, it is an honored term for an idea that has been
elaborately analyzed, has not been falsified, and has made testable predictions
that have later proven to be true. The ordering of scientific notions is:
conjecture, hypothesis, theory. Pope John Paul II chose his words carefully
when in 1996 he called evolution "more than a hypothesis." Yet the very sorts
of elite-institution academics who snigger at creationists for revealing their
ignorance of scientific terminology by calling evolution "just a theory"
nonetheless uniformly say "string theory." Since what they're talking about is
strictly a thought experiment (just try proving there are no other dimensions),
from now on, "string conjecture," please.

Smolin concludes The Trouble With Physics with a sense of urgency. The first
two-thirds of the 20th century produced fundamental breakthroughs in
physics-relativity, quantum mechanics, the Standard Model of the interior
forces of the atom. The final third was nowhere near as productive, while
researchers repeatedly got hit over the head by the unexpected, such as dark
energy. It is imperative, Smolin thinks, to stop talking sci-fi claptrap about
alternate universes and get back to figuring out why our own physical world is
as we observe. Perhaps Smolin is right that pure-physics breakthroughs are an
imperative. Or perhaps stumbling around in the dark will be the physicist's lot
for generations to come-my guess is that we know the first 1 percent of what
there is to be known, and it may be centuries before we learn such things as
why matter exists. If we ever know.

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