Gordon D. Pusch wrote in message
...
"Old Man" writes:

Gordon D. Pusch wrote in message
...
"Old Man" writes:
[...]
Rest mass of a single photon is zero, and a single
photon doesn't have a rest frame. However, observe that two
photons, with identical energy, E, but with appositely directed
momentum, E / c = p1 = -p2, have total rest energy of 2*E wherein
the gravitational mass of the two photon system is M = 2*E / c^2.
In the center of momentum system, total energy gravitates. If
the two photons are travling in the same direction, such that
p1 = p2, then the total rest energy is zero because, in this case,
it is impossible to define a center of momentum frame.

The "rest frame energy" (actually, "Center of Momentum frame energy")
is not "zero" in the "parallel" case, but rather =UNDEFINED=, because
_NO SUCH "REST FRAME" EXISTS_.

And in any event, such hand-waving attempts to make naive analogies
between Einsteinian and newtonian physics are at best ill-justified,
and at worst, JUST PLAIN =WRONG=. Newtonian physics is the "weak field,
slow motion" approximation to General Relativity --- and photons CANNOT
be considered "slow moving" in any Einsteinian sense !!!

Pusch suffers from delusions of competence. [Old Man]

"{Old Man]" suffers from projection of his own delusions of competence on
others, as well as some VERY peculiar notions regarding how relativistic
physics works --- no doubt because he is largely self-taught (as I believe
he has admitted in this forum), and has not interacted sufficiently with
other physicists during this process to correct his own conceptual errors.
I strongly suggest he crack the books again, because he is quite, quite
wrong in this case.

The correctness of Pusch's assumptions about Old Man are on par
with his inability to see through his own delusions of competency.
[Old Man]

-- Gordon D. Pusch