A homage to E.C.G.Sudarshan: Superluminal objects and waves (An updated overview of the relevant experiments)

Abstract

This writing has been prepared on the occasion of the 75th birthday of E.C.George Sudarshan, who (besides the originator of the V-A theory for weak-forces, of quantum optics --the quantum representation of coherent light--, of dynamical maps for open quantum systems, of the Zeno effect, etc.) was a pioneer, already in the sisties, also of the theory of the so-called "tachyons". This paper wishes to be a homage to E.C.G.Sudarshan, in connection with the last-mentioned pioneering work of his. After a brief theoretical introduction (based on the standard postulates of Special Relativity, and therefore extending it --or rather non-restricting it-- without any violations: for example, without any violations of the so-called Einstein causality), the main aim of this article is an updated presentation of the status-of-the-art of the "superluminal" experiments. In particular, we devote such a review to the phenomena met in tunneling through quantum (and classical) barriers [e.g., referring to the Genelalized Hartman Effect]; and in connection with the "Localized (nondiffracting) Solutions" of the wave equantions [e.g., of Maxwell equations]: especially of the "X-shaped" ones. The interested reader is provided with an extended Bibliography.