Richard Clark wrote:
What is mass times the speed of light
for a particle that has no mass?

A nonsense question since "no mass" for a
photon is associated with it being *at rest*,
i.e. *not moving at the speed of light*.

Perhaps Tom's special reading skills can rescue this p term from the
oblivion of E = 0 for a (p)hoton.

For a photon possessing zero rest mass,
traveling at the speed of light yields
a finite measurable mass.
--
73, Cecil http://www.w5dxp.com