The Theory of Special Relativity postulated by A. Einstein in combination with the transformation equations derived by Larmor, Lorentz
and Poincaré and further the relativistic increase of mass makes it possible to describe all conceivable relations between moving bodies
in arbitrary inertial systems without contradictions. To prove this a wide selection of examples concerning this issue was already
discussed in detail in the chapters presented before.
However, this concept is not sufficient to describe all observed cosmological cases. At the beginning of the second half of the 20th
century it was found that a cosmic microwave background radiation exists, which is isotropic and constant in all directions. Therefore,
based on the “Ether-theories” already developed at the end of the 19th century, new attempts were made to bring special relativity in
accordance with a state of absolute rest. However, none of these theories were able to show results without severe discrepancies to
experimental findings. The most important theories will be discussed briefly in the following. In addition, the Einstein synchronization
already discussed in chapter 3.4. will be evaluated again.
Furthermore, it is proved that by using light pulses for a signal exchange between two observers moving arbitrarily to each other, additionally
a superordinate system of absolute rest can be incorporated. With the use of the Lorentz transformation as only precondition this system
can be integrated without contradiction. This is done first for the case that two observers are on a straight line in orientation to the system
at rest, then for arbitrary constellations.