[dleviwing]

Originally Posted by subversion

but according to gravity what difference is there??
And whose opinion is more important, your's or gravity's?

Sub;
A wave cannot be at "Rest" and thus EM radiation's rest mass is assumed to be zero.
Since gravity has not expressed an opinion, my opinions and the statements of facts are quite predominant here.

An EM wave is a form of angular momentum and thus part of the "Conservation of angular momentum". Momentum is the product of velocity and mass.

Unfortunately Duane has made improper assumptions of the equations that are too extensive to answer in detail.

The six page post should be placed as an article or as his journal.