Friday, July 07, 2000

Unification



>   What do you think the odds are that a unified theory of physics will be
> discovered within our lifetime?

Heh, good question -- there are a few assumptions in the phrasing, but let
me address the main issue first...

The currently popular main line of research on this problem is categorized
as string theory, which sprung out of some funny ideas in quantum field
theory.  There are a great number of brilliant people all hammering away
at stringy problems -- but the lack of any experimental support whatsoever
has resulted in a huge body of theoretical work that branches out in
mathematically beautiful and interesting directions but has no connection
with physical reality.  It's a real stretch to call string theory
"physics" anymore.  But the research and funding seems driven by
popularity and novelty, so "progress" keeps being made without any
experimental verification.  These days, this herd has bored with
1-dimensional (or 2, if you count time) strings and is working on
"M-theory," which is either the super-quantum dynamics of higher
dimensional membranes, or matrices, depending on who you read.

In my opinion, the odds are very low that the string herd will succeed at
arriving at a TOE.  There are just too few and tenuous connections between
their theories and experimental verification to believe that it might be
physically relevant.  However, there are other lines of research, and you
can bet that if they pan out that the string gang will all hop over and
apply some prodigious mathematical talent to whatever emerges, and
probably make connections to string theory.  In fact, the string gang
might get a pretty lethal blow, and be dispersed to other studies, if the
particle accelerators fail to turn up super-particles over the next ten
years or so.  So, on to some of those other approaches:

The next biggest arena of research, after string theory, is somewhat more
grounded in established theory.  It is the collection of attacks on the
problem of quantum gravity.  You might think that this would be a side
issue to "unification," but it is the key issue.  It is only general
relativity and quantum mechanics (more specifically, quantum field theory)
that have not been unified, and if anyone can figure it out, they will be
a god and get all the chicks they want. (It is, after all, frustrated
sexual fantasies and delusions of grandeur that fuels all great scientific
work.)  After some one comes out with a good theory of quantum gravity,
the deal will be mostly done, except for correctly incorporating matter
fields into the theory, which shouldn't be too hard if the rest is right. 
However, I don't think the odds of someone coming up with the right match
of quantum mechanics with general relativity are that hot either, since
there are too many things that only sort of work.

My personal attack on unification is to try figure out how to sensibly
describe quantized matter fields in the geometric context of general
relativity, and get the whole thing together after that -- sort of like
putting together the edges of a jigsaw puzzle first, before filling in the
center.  Of course, we went and lost the picture on the box, and have to
cut out some more pieces from cardboard -- and make up bad analogies and
beat them into the ground.  But, anyway, I don't give my own approach very
high odds, but it's a fun game -- and, obviously, I think it's got the
best chance of success.

So, in sum, the odds seem low.  But, there are a couple of loopholes in
your question...  First off, computers kick ass -- and, probably within
our lifetimes, some mad scientist somewhere, possibly my friend B,
is going to hack together some code that thinks.  And, after that, the ass
that the computers kick will be ours!  So, once synthetic intelligence
significantly supersedes human intelligence, the machines will crack the
little unified theory puzzle over afternoon tea -- but they might not tell
us!  The other, more optimistic, loophole is the possibility of life
extension.  Give me another couple of hundred years before my brain decays
and I'll wrap this baby up, no problem.  Heh -- as long as the surf isn't
too good and my girlfriend doesn't pester me the whole time.


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