Pentcho Valev

In Section 22 in his "Relativity" Einstein denounces the validity of the postulate of constancy of the speed of light in a gravitational field: "A curvature of rays of light can only take place when the velocity of propagation of light varies with position." This means that, if the position in question is occupied by an observer, this observer will measure a speed of light different from (e.g. greater than) c. The line of argument can be continued by applying the equivalence principle – then it will turn out that the measured speed of light depends on the speed of the observer (see http://www.wbabin.net/valev/valev3.htm ).

The discovered falsehood of the fundamental postulate should have made Einstein write extensive papers exploring all the consequences and convincingly explaining why an observer measuring a variable speed of light should nevertheless continue to believe in the theory of relativity. Needless to say, Einstein did not do so. Why? Is only his ethics to blame?

The problem is ethical indeed but by no means restricted to Einstein’s personal ethics. Sooner or later, any mythology becomes stronger than and determines the behaviour of its creators. According to the most extreme version of this view, even if Einstein had tried to write the papers and draw some fatal conclusions, he would not have been allowed to materialise his intentions.

Something similar has happened in thermodynamics. Clausius’s mythological principle "Entropy always increases" emerged as a conclusion in the following argument:

Premise 1: Any irreversible process in a closed system connecting some initial and final states can be replaces by a reversible process connecting the same initial and final states. In other words, any irreversible process can be closed by a reversible process to become a cycle.

Premise 2: ∫dQ/T ≤ 0 for any cyclical process.

Conclusion: Entropy always increases (never decreases).

By the end of his career Clausius abandoned the conclusion (see T. Kuhn, Black-Body Theory and the Quantum Discontinuity, 1894-1912, University of Chicago Press, 1978, pp. 13-15, p. 260), possibly because he had seen the almost obvious falsehood of Premise 1 and a fatal ambiguity in Premise 2. Yet this indecisive attempt at rectification proved totally useless because the conclusion had already become fashionable. In science, as elsewhere, "fashionable" means prestige, careers, money etc. and sycophants would allow nobody, not even the author, to withdraw the concept and deprive them of their fair share.

Let us return to Einstein and his theory. Philosophers of science often say that, even in the presence of anomalies, no theory should be abandoned except in favour of a better theory. For the sake of argument let us agree with them. But while saying so philosophers implicitly assume that the better theory can only be looked for in the future, not in the past. This can be tested.

In so far as the postulates are concerned, Einstein’s theory differs from Newtonian mechanics in that in the latter the speed of light is relativistic in the Galilean c+v (corpuscular, ballistic) sense whereas Einstein has replaced this with the postulate of constancy of the speed of light (the speed is relativistic in the c sense). However in Section 22 Einstein declares that this postulate is generally false. Then which theory is better?

Let us assume that both the c+v and c interpretations are false. This may mean that Einstein has replaced a false postulate with a "less false" one so that in the end a "less false" theory has emerged. Is that a realistic scenario? Relativists would simultaneously shout out "yes, yes, yes" three times but that would not be enough. Additionally, they should read carefully Section 22 in Einstein’s "Relativity" and show quantitatively how exactly the speed of light changes as measured by an observer situated in the gravitational field. They will only be able to do so by applying the equivalence principle and showing, quantitatively, how exactly the speed of light depends on the speed of the accelerating observer. Finally, the moment they come to the inevitable conclusion that the c+v interpretation is correct, they should shout out "sorry, sorry, sorry" three times again.