How so you found the speed is the square root of (2 times the speed of light)?
Actually it is 1.4142... times the speed of light and 1.7321... times the speed of light. Maximum for photon motion is 2c. This include the maximum universal spacetime expansion.
Time independence: [∂E(g)]²=[∂F(a)×∂r(a)]·[∂F(b)×∂r(b)] and Mass independence: ¶a(t)·¶r(t)=c²
Antonio;
Are you suggesting that a photon is a traveling particle of EM radiation?
The velocity of a reflected wavefront of EM radiation is 1.732.
In Relativity Einstein's equations indicate a maximum of 2c but that is due to his assumption of c as the ultimate velocity. In QM this velocity is 6.5x10^11c.
Which one do you think is right (if either), Relativity or QM?
The phase velocity and group velocity of a wave may exceed the speed of light, but in such cases, no energy or information actually travels faster than c. Experiments showing group velocities greater than c include that of Wang et al. (2000), who produced a laser pulse in atomic cesium gas with a group velocity of 311c. In each case, the observed superluminal propagation is not at odds with causality, and is instead a consequence of classical interference between its constituent frequency components in a region of anomalous dispersion (Wang et al. 2000).
Time independence: [∂E(g)]²=[∂F(a)×∂r(a)]·[∂F(b)×∂r(b)] and Mass independence: ¶a(t)·¶r(t)=c²