R Kym Horsell wrote on 19/5/21 11:21 pm:
R Kym Horsell wrote:
wrote:
Photons have no mass.
Observed or measured speed in any inertial frame will always be c .
Bzzzt.

For any remaining hillbilly parrots that dont know what they are
talking about.

c is the speed of light in a vacuum.

What is the definition of "a Standard Vacuum"??

Is one Hydrogen atom per cubic kilometre "a Standard Vacuum"?? How about
one atom per million cubic kilometres??
--
Daniel