Re: [Phys-l] Mass and Energy

[Hugh Haskell <hhaskell@mindspring.com>]

>  	Sorry, but the physics of gquarks and gluons is considerably more
> complicated than that.  I don't want to get into great detail, ut the
> notion "kinetic energy of a quark or gluon inside a proton" may not have
> much meaning.  The trouble is that neither a quark nor gluon has any
> existence outside of a proton (or other hadron) so the notion of mass is
> hard to pin down.  (For ordinary particles we make our mass determinations
> - physically and conceptually - in terms of the isolated particle).  There
> is no such thing as an isolated quark or gluon.
>  	The "glue" that holds a quark inside a proton is not very
> stretcheable.  Think of the quark as moving at times to the boundary of
> the proton and stretching the "glue".  When this happens, the energy is in
> the stretch.  So a model of what is going on is a harmonic oscillator that
> is continuosly transferring its energy back and forth between kinetic and
> potential.

I am aware of most of that, at least in a general way. What I was 
trying to do was to suggest what the author of the statement about 
90% of the energy in the universe being kinetic energy might have had 
in mind.

I once tried to do a simple-minded calculation of the "binding 
energy" of a nucleon by estimating the momentum of quarks from the 
uncertainty principle, assuming that the quarks were confined to the 
volume of the nucleon, and gong from there to the energy of the 
quarks, but even that didn't give me anything like the mass of the 
nucleon, so I had to assume that whatever was left over was in the 
energy of the gluons, but then I was stuck, because I don't know how 
to figure out what the gluon contribution to nucleons is (how many, 
how long-lived, etc.). Since then, I have left the figuring about 
those matter to those who know what they're doing.

Hugh
--

Hugh Haskell
<mailto:haskell@ncssm.edu>
<mailto:hhaskell@mindspring.com>

(919) 467-7610

Never ask someone what computer they use. If they use a Mac, they 
will tell you. If not, why embarrass them?
			--Douglas Adams
******************************************************