Special Relativity: from metric to philosophy

The Theory of Relativity from Einstein starts from some everyday system of Cartesian space- coordinates plus a linear time-parameter, read from a good old grand-father’s clock. The theory then contemplates a group of certain homogeneous, linear transformations with constant coefficients, transformations which involve all four coordinates and which there is reason to interpret as going over the another inertial systems, that moves with constant translational velocity with respect to the first. In fact the very backbone of the theory is that all laws of nature shall be the same for every frame reached in this way, including the original one from which we started, there should be no difference or distinction in principle between all these inertial frames, any one of which can be reached from any other one by a transformation of that group a so called Lorentz-transformation. In short, all laws of nature are assumed to be invariant to Lorentz- transformation.