Special Theory of Relativity Postulated on Homogeneity of Space and Time and on Relativity Principle

In Special Theory of Relativity time is considered to be the 4th dimension of space – time as a consequence of Lorentz invariance and Minkowski metric, in turn based on the invariance of light speed . In this paper we’ll show that, starting only from universal postulates as homogeneity of space and time and Principle of Relativity, we can obtain space and time transformations (as the Lorentz and Tangherlini – Selleri ones) characterized by an invariant speed generally different than . These results determine crucial difficulties in the assumption of Minkowski metric and consequently in the interpretation of physical time as the 4th component of space – time, also introducing a “relativity” feature in the velocity of light in vacuum being no longer considerable as a necessarily universal invariant quantity and depending on the physical properties of space which originate from quantum vacuum. A novel interpretation of time, coherent with these results, defined as duration of material change in space, i.e. motion, is finally proposed.