NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/sci/physics/23441

Internet Message Format | 1993-01-25 | 2.4 KB

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From: [e-mail] (Matt McIrvin)
Newsgroups: sci.physics
Subject: Re: Truth vs beauty in physical theories
Message-ID: <[e-mail]>
Date: 25 Jan 93 19:15:35 GMT
Article-I.D.: husc.mcirvin.727989335
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[e-mail] (Robert Coe) writes:

>For at least the last 300 years, the really major advances in our under-
>standing of the universe have come not from the discovery of increased com-
>plexity (important as such discoveries have been), but from the eventual
>realization that the complexity could be best understood in the context of
>a more global, but ultimately simpler, synthesis.

Maybe.  And I hope this continues.  But it is a little disquieting to
me to observe the state of affairs with the electroweak theory.
This is a theory with great predictive and explanatory power,
that simplifies things in the sense that it identifies weak interactions
as a gauge phenomenon.  However, it has some seemingly kludgey aspects, and
calling it a "unification" theory is a bit of a stretch since it has
a non-simple gauge group with two coupling constants, not to mention
the Higgs, and a weird structure with regard to the quarks and leptons.

Compare this with QCD.  QCD is simplicity itself by comparison.  The
gauge group remains unbroken down to low energies and the couplings
are all vector couplings.  There's no fundamental scalar necessary, or
groupings by chirality into gauge singlets and doublets.  The downside is
that nobody can do really good calculations since the coupling is so strong.

Now, I fervently hope that this picture, which seems to be groping
toward extreme elegance, turns out to emerge from something simpler and
more beautiful.  But I worry that the reason the electroweak part
of the standard model seems so much more complicated than the QCD part
might be that it's better verified!  Might QCD turn out to require nasty
tweaking once we get better ways to check theory against experiment?

Of course, the picture is remarkably unified compared to what existed
some decades ago; we're fairly certain that quantum field theory is at
the root of it all, at least down to very small scales, and gauge
interactions seem to be responsible for everything except (possibly)
the Higgs.
--
Matt McIrvin