Introduction

The main part of criticism of TO from previous Chapters was founded on the so-called mental experiments. We make some trivial note to prevent the absurd question about the technical practicability and experimental accuracy of mental experiments. It is generally accepted from Galileo's time that the construction of mental experiments uses notions and principles of some theory under criticism and demonstrates their inner inconsistency. As the result, the value which can be compared with experiments is absent at all. A logical contradiction brings the final dot into the development of any theory. Nevertheless, to form the "complete picture", the consideration of the relativity theory will be continued from the experimental point of view. Real experiments will be analyzed in this Chapter 3, and errors in the interpretation of these experiments with the relativity theory will be shown. To initiate the reflection on relativistic experiments, we consider ideas which could be "almost not conflicting" with SRT (but afterwards we step-by-step will pass to the criticism).

Introduction of Chapter 3 we begin with the question, which is principal for the relativity theory: is light speed constant? The answer to this question was seemingly given by the Michelson-Morley experiment to study the influence of the Earth movement on the speed of light, plus similar optical experiments made by Morley alone, Kennedy - Thorndike, the Jene experiment of Joose and others [7,61,83]. We note, however, that there have been attempts to correct SRT [79,97,116], and to revive the Lorentz ether theory [1,42,64,95,108,119].

However, the term "constant" implies independence from time, spatial coordinates, light propagation direction, and, finally, characteristics of the light itself. An effort must be made to give an unprejudiced answer to the question: What matter could be identified in Michelson's interferometer? Notice that no speed is determined in the Michelson experiment at all, but some remainder of phases of rays is observed (and we can indirectly judge by the speed only). Recall that light was made to traverse two mutually perpendicular directions. We note also the following: To avoid the synchronization of timepieces at different points, both light beams traveled over a closed path; namely, in two mutually opposite directions. Therefore, only some "average" light speed, involving opposite directions, could actually be determined.

Seemingly, Michelson's result can be stipulated as follows: light speed in two mutually opposite directions and at given frequency in some particular system is independent of the motion of this system. Apparently, at least two questions arise concerning the Michelson-Morley result:
1)  Is light speed constant regardless of propagation direction ${\bf k}_1 = {\bf k}/k$, or might it be anisotropic, $c = c({\bf k}_1)$? This question can be put in a broader sense: Does light speed depend on time $t$ and spatial coordinates ${\bf r}$ or not? However, such questions are beyond present theoretical and practical test of SRT, since they involve the problem of space-time structure as such. Problems of this type will not be discussed here, since their experimental verification requires the "basic system" to possess the nonelectromagnetic nature in order to measure the distances and synchronize the time pieces.
2)  Some more practical question arises: Does light speed in vacuum depend on the characteristics of the light itself. In particular, does there exist a dependence on frequency $\omega$; i.e. does $c = c(\omega)$?

The physical (philosophical) meaning of light-speed constancy is (from SRT textbooks) as follows: Let the light be capable of propagating in vacuum without any intermediate medium. Because the system of reference cannot be rigidly "tied" to the "emptiness", it does not matter at what speed our system moves with respect to vacuum. Therefore, light speed with respect to our system must be independent of the system motion (although other particles can move in vacuum with different velocities (?!) depending on system velocity). However, the following questions arise: 1) Do vacuum properties change when particles (photons) are brought into the vacuum? 2) What is the mechanism for propagation of electromagnetic oscillations in vacuum? Some particular hypotheses answering these questions will be presented in Appendixes.

What in particular can be determined from present experiments will be analyzed in detail in the given Chapter 3. As the result, detailed criticisms of relativistic interpretation of some well-known experiments and of observable data, which were inadequate attributed in active of SRT and GRT, will be given. The single, seemingly "working part" of SRT - relativistic dynamics - will be considered in detail in the next Chapter 4.