John Smith I wrote:
Really? I am going to have to see that one to believe it (not saying it
is incorrect though), a "something" with no mass--kinda like a "ghost
particle!"

It's old hat knowledge, John, and one of the reasons
why standing wave energy doesn't just stand there or
just "slosh around" as one guru asserted. If a photon
is slowed to zero velocity, its mass vanishes and
it ceases to be detectable. A photon's mass derives
from its speed-of-light velocity, i.e. it is 100%
kinetic. Any particle with a resting mass would necessarily
have infinite mass at the speed of light. Therefore, any
particle with a finite mass at the speed of light must
necessarily have a zero rest mass.
--
73, Cecil http://www.w5dxp.com