Stephen Paul King (stephenk1@home.com)
Wed, 17 Mar 1999 14:56:48 GMT
Dear Hitoshi,
This is excellent! :) I have been thinking of the meaning of
<<physics>> and this is VERY similar to my thinking! A <<physics>> is
NOT unique, it is a language to describe the patterns that can be
observed in a given cosmos.
Later,
Stephen
On Fri, 19 Feb 1999 02:43:33 GMT, selipsky@wuphys.wustl.edu (Stephen
B. Selipsky)wrote:
>In <7ack8q$tp6$1@pravda.ucr.edu> john baez wrote:
>> Eric Forgy <ericf@empc07.ece.uiuc.edu> wrote:
>[...]
>> >Is it just me, or does the idea of tagging on these subspace manifolds
>> >(U(1) for electromagnetics, SU(2), SO(3) etc for other gauge theories)
>> >seem somewhat artificial?
>>
>> Well, what's artificial is that, except in the case of gravity, one
>> chooses the group for no obvious reason other than to fit experimental
>> data. [...] One can't help but want to know: WHERE ARE THESE GROUPS
>> COMING FROM???
>>
>> And that's why most work on particle physics after the Standard
>> Model has concentrated either on simplifying the gauge group (as in
>> so-called grand unified theories), or even better, "deriving" it from
>> some other principle (as in string theory). Unfortunately none of
>> these attempts has succeeded quite as well as one would like. But
>> they are certainly worth learning about - especially if you find this
>> puzzle appealing!
>
> One lesson we're learning from dualities, supersymmetric gauge
>theory exact solutions, And All That, is:
> A gauge symmetry isn't fundamental, but rather is a redundancy in
>*our choice for describing* nature. In a wide class of field
>theories, the long wavelength limit and possibly much more can be
>described using different degrees of freedom with different gauge
>groups, related by duality and giving exactly the same physics.
>Different phases of a theory are described most simply or tractably
>by different choices of "fundamental" degrees of freedom. Certainly
>in string theory it's turning out that fundamental degrees of
>freedom, and composite effective d.o.f., can be interchangeable.
> That might still leave questions about which *sets* of
>duality-related gauge groups + matter, are actually chosen by
>Nature; but it widens the question somewhat-- maybe there is no unique
>math-mystically PC (Pythagoreanly Correct) gauge group.
>---
>Stephen B. Selipsky selipsky@wuphys.wustl.edu
>Washington Univ. Dept. of Physics Phone: (314) 935-4064
>1 Brookings Dr., Campus Box 1105 Fax: (314) 935-6219
>Saint Louis, MO 63130-4899 USA Home: (314) 863-7351
>
>[My permanent email address <stephen.selipsky@iname.com>
> will continue forwarding to me after March '99; wustl addresses
> not guaranteed after that.]
>
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