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- From: mcirvin@husc8.harvard.edu (Mcirvin)
- Newsgroups: sci.physics
- Subject: Re: Axiom of Physics
- Message-ID: <mcirvin.715198792@husc8>
- Date: 30 Aug 92 18:19:52 GMT
- References: <1992Aug26.174922.6115@pellns.alleg.edu> <10510@sun13.scri.fsu.edu>
- Lines: 34
- Nntp-Posting-Host: husc8.harvard.edu
-
- jac@ds8.scri.fsu.edu (Jim Carr) writes:
-
- >A better example than the one discussed in this thread, the conservation
- >laws, might be the axioms of QCD. Here one states that the interaction
- >between quarks is governed by the generators of the mathematical "group"
- >known as SU(3), with an empirical coupling constant, and procede to
- >derive or compute the properties of protons etc etc and compare them
- >to experiment.
-
- If only this could actually be done! In QCD today, there are usually
- a large number of extraneous assumptions that have to be made before the
- comparison with experiment can occur, since nobody knows how to calculate
- the properties of protons, etc. from first principles. It is believed
- and hoped that all of this will eventually follow from QCD alone, since
- QCD is aesthetically appealing and doesn't seem to directly contradict any
- of the evidence. For now we have to rely on things like the parton
- model, the infinite-mass approximation for heavy quarks, and other stuff
- that is not strictly included in the axioms. Lattice gauge theory is
- closer to doing calculations with QCD directly; it's in its infancy, and
- the extent to which it succeeds will depend in part on the availability
- of sufficiently capable computers.
-
- >This is a very abstract starting point. It is related
- >to the earlier inductive insight into use of the SU(3) group for
- >the description of patterns in the masses of particles, but only in
- >a mostly accidental way.
-
- For one thing, a different SU(3) is involved. It's interesting that
- the gauge groups that have been incorporated into the standard model
- (SU(3), SU(2), and U(1)) are all groups that originally came up in
- different physical contexts (hadron flavors, spin, and nonrelativistic
- wave functions, respectively).
- --
- Matt McIrvin, Cambridge, Massachusetts, USA
-