[deleted]
Vladimir,
The fact that the speed of light varies with phi, the gravitational potential, cannot be denied. In 1911 Einstein adopted the equation c'=c(1+phi/c^2) given by Newton's emission theory of light, then in the final version of general relativity the speed of light became even more variable: c'=c(1+2phi/c^2).
Yet Einsteinians never discuss this for a simple reason: if photons slow down as they leave the gravitational field of a star, then they come here on earth at a decreased speed c' lower than c. Einsteinians exercise themselves in crimestop in such cases:
George Orwell: "Crimestop means the faculty of stopping short, as though by instinct, at the threshold of any dangerous thought. It includes the power of not grasping analogies, of failing to perceive logical errors, of misunderstanding the simplest arguments if they are inimical to Ingsoc, and of being bored or repelled by any train of thought which is capable of leading in a heretical direction. Crimestop, in short, means protective stupidity."
Pentcho Valev