[net.physics] Massive fermions - minor quibble.

JGA%MIT-MC@sri-unix.UUCP (10/31/83)

From:  John G. Aspinall <JGA @ MIT-MC>

    Date: 25 Oct 83 19:40:08-PDT (Tue)
    From: hplabs!hao!seismo!rlgvax!guy at Ucb-Vax
    To:   physics at Sri-Unix
    Re:   Relativity - Making Space
    Received: from Usenet.uucp by sri-unix.uucp with rs232; 29 Oct 83 4:23-PDT
    Article-I.D.: rlgvax.1337

    A minor quibble: your distinction between bosons and fermions should be
    between "luxons", i.e. massless particles travelling at C, and "tardyons",
    i.e. massive particles travelling slower than C.  There are both massive
    and massless bosons, and there may be massive fermions (the rest mass of
    the neutrino is currently being debated).

    	Guy Harris
    	{seismo,mcnc,brl-bmd,allegra}!rlgvax!guy

There sure are massive fermions - electrons, protons, and neutrons, to
name three fairly common ones.

guy@rlgvax.UUCP (Guy Harris) (11/01/83)

Yes, yes, typo, sorry.  Yes there *are* massive fermions, I meant to say
there was debate over whether there were *massless* fermions (some people
are proposing a small rest mass for the neutrino).

	Guy Harris
	{seismo,ihnp4,allegra}!rlgvax!guy

halle1@houxz.UUCP (11/02/83)

Obviously, massive was meant to be massless.  However, protons and
neutrons are not fermions, massive or otherwise.  They are BOSONS.

JGA%MIT-MC@sri-unix.UUCP (11/07/83)

From:  John G. Aspinall <JGA @ MIT-MC>

    --------
    Date: 2 Nov 83 5:19:17-PST (Wed)
    From: ihnp4!houxm!houxz!halle1 at Ucb-Vax
    To:   physics at Sri-Unix
    Re:   Massive fermions - minor quibble.
    Article-I.D.: houxz.568

    Obviously, massive was meant to be massless.  However, protons and
    neutrons are not fermions, massive or otherwise.  They are BOSONS.
    --------

Oh dear.  Perhaps we'd better make some definitions.

Bosons : - Obey Bose-Einstein statistics
         - Integral spin
         - Do NOT obey an exclusion principle

Fermions : - Obey Bose-Einstein statistics
           - Half-integral spin
           - Do obey an exclusion principle

Using the spin property and the type of interaction we can also classify

Leptons : Half-integral spin, electro-weak interaction
Mesons  : Integral spin, strong and other interactions
Baryons : Half-integral spin, strong and other interactions

(This is not all-inclusive, for instance the photon doesn't fit in any of these.)

There are "shells" and energy levels in nuclear structure, just as there are
in atomic structure.  Strong evidence of an exclusion principle at work.
Evidence of shell structure in nuclei includes gamma decay, large numbers of
nuclei with "magic number" N and Z - such as 20, 28, 50, 82, ground-state
angular momenta of nuclei, and hyperfine splitting of atomic spectra.

John Aspinall.

Shinbrot.WBST@PARC-MAXC.ARPA (11/08/83)

John,

I assume there was a typo, meant to read:

"Fermions : - Obey FERMI-DIRAC statistics
           - Half-integral spin
           - Do obey an exclusion principle"

- Troy

dnc@dartvax.UUCP (11/12/83)

 
Thank you for claring up the matter (energy?) about spins and applicability
of the various statitc.
I am assuming that you meant that ferions obey fermi dirac statistics, not
boe einstein. and it was a typo.
(pardon mine, this terminal is old.)