🚀 go-pugleaf

 ... note followups; add another if desired ...

Fred McGalliard <frederick.b.mcgalliard@boeing.com> writes:
>
>But now I would like to take this a few steps deeper. What mass do I
>deal with when the object is a collection of confined photons, and
>possibly some neutrinos. 

 You always use the invariant mass, which is the total energy in the 
 center-of-momentum frame of the manybody system. 

>The rest mass of a confined photon should be
>it's ordinary mass, or just it's energy, eh? 

 Just its (total) energy.  This is why the mass of a bound system 
 like an atom or nucleus is less than the mass of the constituents. 

>When the confined photons go streaming off to infinity, they can leave
>as much as all of their mass/energy behind. 

 Nope.  They reduce the total energy (hence the mass) of what is left 
 behind by the amount of energy they remove. 

-- 
 James A. Carr   <jac@scri.fsu.edu>     |  "Whatever."  
    http://www.scri.fsu.edu/~jac/       | 
 Supercomputer Computations Res. Inst.  |      George Herbert Walker Bush 
 Florida State, Tallahassee FL 32306    |