ethan@utastro.UUCP (Ethan Vishniac) (05/15/84)
[If this is the answer, what was the question?]
The question has recently arisen, in connection with the cosmology
debate, on the extent to which one can imagine that all known particles
are merely composities of some very simple structures. There is an
article in a recent SciAm on this topic (sorry, don't remember the
month). The essential problem is as follows.
It is now widely believed that baryons and mesons are composite
particles made up of quarks whose interactions are mediated by
gluons. In this picture we have 3 "generations" of particles
which for leptons are electrons, muons, and tau particles with
their accompanying neutrinos, and for quarks are three pairs
(up/down, strange/charm, top/bottom [ or truth/beauty]). In addition,
there exist various particles (photons, W and Z bosons, gluons, and
gravitons) that mediate the forces of nature. This may simply be
some small fraction of a larger picture. The question has naturally
arisen: could these particles represent the rearrangement of few
basic particles (called preons or rishons or ...). The major
difficulty is that the effective "size" of quark is very small and
the mass of a up or down quark is only a fraction of a proton mass.
In order to fit smaller particles inside a quark they must have
tremendous momentum (Heisenberg uncertainty principal del p x del x
is less than Planck's constant). Therefore they must have a large
energy, which in turn corresponds to a mass which is much greater than
the mass of the quark into which they fit. It is not clear how to
make this work.
"Just another Cosmic Cowboy"
Ethan Vishniac
{ut-sally,ut-ngp,kpno}!utastro!ethan
Department of Astronomy
University of Texas
Austin, Texas 78712neal@denelcor.UUCP (05/22/84)
************************************************************************** > The major >difficulty is that the effective "size" of quark is very small and >the mass of a up or down quark is only a fraction of a proton mass. >In order to fit smaller particles inside a quark they must have >tremendous momentum (Heisenberg uncertainty principal del p x del x >is less than Planck's constant). Therefore they must have a large >energy, which in turn corresponds to a mass which is much greater than >the mass of the quark into which they fit. It is not clear how to >make this work. This brings up a hypothesis I have heard now and again: Since the mass of any particle is equal to the mass of its "constituent particles" MINUS the mass equivalence of the "binding energy" (e.g., the mass of a helium-4 nucleus is somewhat less than the sum of the masses of two protons and two neutrons), why wouldn't it be possible that quarks (for example) are "made up of" particles that are INDIVIDUALLY more massive than quarks with the excess being accounted for by a (VERY LARGE) binding energy? I can think of three objections to this hypothesis but none of them seem fatal: 1. It's counterintuitive. This hasn't been a serious objection in physics for almost a century. 2. It leads (potentially) to an infinite regress. This is philosophically "uncomfortable" but not enough so to reject the hypothesis. 3. If it ever were "verified" by an experiment, it would be difficult if not impossible to resolve the question of whether the new particles were actually "constituents" of the quark (or whatever) or just artifacts of the very high energies that went into the experiment. How about it? Is this hypothesis completely ridiculous or might it be a serious possibility? Regards, Neal Weidenhofer "Nothin' ain't worth nothin' Denelcor, Inc. but it's free" <hao|csu-cs|brl-bmd>!denelcor!neal
crummer%AEROSPACE@sri-unix.UUCP (05/24/84)
From: Charlie Crummer <crummer@AEROSPACE> Haowdy theah Ethan! Whut evah happuned tew the theora uv bootstrappin'? Yew remembuh. Everthin' wuz made outta everthin'; nucleons wuz made outta mesons 'n mesons wuz made outta nucleons. The hole shebang wuz a self- producing (autopoietic) sistum. AH thank we all got western blahnders ohn! All us cowboahs jes BULEAVE that the world has GOT to be wun great big Chaneeze box. Yew know, with boxes in boxes... WE thank that we got thangs x-planed when we fahnd the last box. Whut if they ISN'T any last box? Whut if we all sit heah 'n fahnd boxes in boxes 'til HELL freezes ovah 'n nevah see that th' hole prolem is that we don't know hao t' SEE? Ah thank that if we all use Quantum Gauge Field Theory lahk a sodbuster maht yews a samuri sored to plow his field or nok the shit off his boots, we're missin' the point uv whut QGFT kun tell us. Maybe the plowboy kun larn frum jes lookin' at th' plow. QGFT ken handle state functions thet ahrn't ahgenstates uv th' numbah oparatah. Whut duz this meen? MAYBE it's a trap t' keep lookin' at th' world as jes a hole bunch uv little tahny THANGS a-buzzin' 'round; MAYBE we ort t' trah t' unnerstand it as a big ol' blob uv self-generating jello, a-wigglin and a-shakin. --Charlie