Blog Ekkehard Friebe

Ich nehme Bezug auf meinen Blog-Eintrag: Nikolai Rudakov: „Establishment”. Aus dem dort genannten Buch (1981): „Fiction stranger than truth – In the metaphysical labyrinth of relativity” von Nikolai Rudakov bringe ich nachstehend eine weitere Leseprobe:

Zitat:

8 Light Postulate
In the preceding chapter we examined the relativity postulate, the first of the two basic premises of special relativity. We will now turn our attention to the second basic premise, the light postulate, which deals with the constancy of the velocity of light. Immediately after announcing the relativity postulate in the introduction of the 1905 paper Einstein says that he is also introducing a second postulate which is only apparently irreconcilable with the first. The second postulate states that light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body. It will be noticed that the postulate consists of two parts. The first says that light velocity is constant, the second that it is source-independent.  –  That the velocity of light is a physical constant was generally accepted by 1905 when Einstein announced his postulate. The elevation of an empirically derived measurement to an axiom did not add anything to physical knowledge. Neither did it provide any new philosophical insight into the nature of light. In terms of Newtonian theory it was an unnecessary and arbitrary manoeuvre. The purpose of axiomatising the constancy of the velocity of light was to endow light with absolute qualities in the mathematical scheme of things, without having to justify it, and to create the required basis for the subsequent development of the theory.

The second part of the postulate asserted that the velocity of light is independent of the motion of the emitting body. The meaning of this phrase and its implications will be discussed in the next chapter. However, two things have to be pointed out at this stage. Firstly, while the constancy Statement could be associated with well-founded physical evidence, the independence Statement represented one of several possible assumptions suggested to explain the behaviour of the velocity of light in the Michelson-Morley experiment. Secondly, contrary to the requirement that motion must always be relative to something, Einstein is now introducing the idea of the motion of light relative to nothing. Previously the light medium was considered to be the hypothetical stationary aether. Einstein specifically excludes it from his theory and maintains that the introduction of a „luminiferous aether“ will prove to be superfluous inasmuch as the view here to be developed will not require an „absolutely stationary space“. In physical terms Einstein’s proposition of source-independent motion relative to nothing is less attractive than the idea of the aether and absolutely stationary space. Einstein is avoiding any discussion about the nature of the medium between inertial Systems. His solution to a difficult problem is to pretend that it does not exist.

In the 1905 paper Einstein offers also a second version of the light postulate: Any ray of light moves in the „stationary“ System of co-ordinates with the determined velocity c, whether the ray be emitted by a stationary or by a moving body. This formulation is probably closer to what Einstein really wants to say than the first one, namely that the velocity of light is the same in all inertial systems. Although this situation appears to be equivalent to the Newtonian position, we are, in fact, no longer within the realm of Newtonian physics since inertial systems are Einsteinian creations subject to the Einsteinian relativity postulate. The use of the word „stationary“ in the expression „stationary system“ is also noteworthy. Einstein is not correct in telling us that it is used purely for convenience or, as he puts it, in order to render our presentation more precise and to distinguish this system of co-ordinates verbally from others. Without the concept of the stationary system the Einsteinian argument would not be able to proceed. It is an absolutely necessary concept. We will see later that the derivation of his transformations requires that the notions of rest and motion be allocated in a specific and non-reciprocal way to the two systems of the Einsteinian doublet. In the quoted second version of the light postulate the expression „stationary“ performs an additional function. It restricts the application of the full light postulate temporarily to light rays in the stationary system. Light rays in the moving system are not subject to this restriction during the crucial stages of the argument.

(Zitatende)

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Beste Grüße Ekkehard Friebe