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Dear Wei and Friends,
I have been
following this thread with some interest (Hal initial post was wonderful,
BTW!) and echo the comments of Wei here, but I would offer a note of
caution: we must be very careful that the elevation of string theory (SUSY) to
almost dogmatic "Sacred Cow" status does not bode well for many of us,
particularly those that have found that its most fundamental assumption, the
existence of a supersymmerty relation between bosons and fermions, has never
even come close to matching experimental observation.
Maybe, just
maybe, SUSY is a good theory or maybe it is just a very elegant bit of pure
mathematics. Remember, just because a mathematical theory can be shown to be
self-consistent and elegant, there is no requirement that that theory have
anything to do with the physical world we experience.
I find that the
choices presented by Weinberg and the Intelligent Design advocates are not the
only possibilities. Consider that we still do not have a consistent and faithful
model of observers within our physics and thus can not even start to coherently
consider what the notion of "comprehensibility" means in the context of physics.
;-)
Onward!
Stephen
----- Original Message -----
Sent: Monday, February 13, 2006 7:06
PM
Subject: Re: Multiverse concepts in
string theory
Hal wrote:
> I also get the impression that Susskind's
attempts to bring "disreputable"
> multiverse models into "holy" string
theory is more likely to kill
> string theory than to rehabilitate
multiverses. Perhaps I am getting a
> biased view by only reading
this one blog, which opposes string theory,
> but it seems that more and
more people are saying that the emperor has
> no clothes. If
string theory needs a multiverse then it is even less
> likely to ever
be able to make physical predictions, and its prospects
> are even worse
than had been thought. A lot of people seem to be piling
> on and
saying that it is time for physics to explore alternative ideas.
> The
hostile NY Times book review is just one example.
String theory isn't going to be killed until
there's a replacement available, and any replacement is likely to face the
same issue of describing a large collection of universes of which only a small
subset can support life. So I wouldn't be concerned about more
effort being devoted to looking for alternatives to string theory. In the mean
time, the multiverse meme continues to spread. Take the review of Susskind's
book in American Scientist (http://www.americanscientist.org/template/BookReviewTypeDetail/assetid/49558) for
example:
In the end, however, good though this book is, I
was left feeling that the argument was not carried to its logical conclusion.
Despite his justified scorn for intelligent design, Susskind retains a hint of
this worldview in his own attitude. It was Galileo who said that the book of
Nature is written in mathematics, and almost all physicists subscribe to this
view. When we contemplate the power and simplicity of constructions like
general relativity, there is a temptation to carry intelligent design to an
extreme in which God wrote the equations, from which all else follows.
Frequently this perspective is quite explicit, as with Einstein (recall Bohr's
admonition, "Stop telling God what to do!"). The landscape picture derails
this thinking to some extent, but Susskind just transfers the quasi-religious
awe to string theory, whose mathematical results he repeatedly describes as
"miraculous."
But if life on Earth is a random accident in a universe where only chance
yielded laws of physics suitable for life, why stop there? Perhaps string
theory itself is nothing special and only part of a wider spectrum of possible
prescriptions for reality. If the search for a unique and inevitable
explanation of Nature has proved illusory at every step, is it really
plausible that suddenly string theory can make everything right at the last?
Reading Susskind's book should make you doubt that possibility, in which case
we may have reached the end of the search for underlying simplicity that has
driven physics since the beginning. A comment made by Steven Weinberg in his
1977 book The First Three Minutes sums things up well: "The more the
universe seems comprehensible, the more it also seems pointless." Pointless to
look for meaning in our existence in the universe, and also (according to
Susskind) pointless to look for meaning in physics. To a physicist, this is a
pretty depressing conclusion, but there is some consolation: The beauty we
perceive in the laws of physics perhaps tells us as much about the human
aesthetic response as it does about any fundamental design of the universe. In
short, physics is a human creative art on the same level as painting and
music, and that is reason enough to be proud of what the subject has
achieved.
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