The Tolman "Antitelephone" Paradox: Its Solution by Tachyon Mechanics

Some recent experiments led to the claim that something can travel faster than light in vacuum. However, such results do not seem to place relativistic causality in jeopardy. Actually, it is possible to solve also the known causal paradoxes, devised for "faster than $c$" motion: even if this is not widely recognized. Here we want to show, in detail and rigorously, how to solve the oldest causal paradox, originally proposed by Tolman, which is the kernel of so many further tachyon paradoxes. The key to the solution is a careful application of {\em tachyon mechanics}, that can be unambiguously derived from special relativity

On Localized "X-shaped" Superluminal Solutions to Maxwell Equations

In this paper we extend for the case of Maxwell equations the "X-shaped" solutions previously found in the case of scalar (e.g., acoustic) wave equations. Such solutions are localized in theory, i.e., diffraction-free and particle-like (wavelets), in that they maintain their shape as they propagate. In the electromagnetic case they are particularly interesting, since they are expected to be Superluminal. We address also the problem of their practical, approximate production by finite (dynamic) radiators. Finally, we discuss the appearance of the X-shaped solutions from the purely geometric point of view of the Special Relativity theory. [PACS nos.: 03.50.De; 1.20.Jb; 03.30.+p; 03.40.Kf; 14.80.-j. Keywords: X-shaped waves; localized solutions to Maxwell equations; Superluminal waves; Bessel beams; Limited-dispersion beams; electromagnetic wavelets; Special Relativity; Extended Relativity].Comment: Replaced in order to add the missing Figures. Paper of 33 pages with 6 Figures, originally submitted for pub. on March 1, 1996 (nineteen ninety-six), and appeared in print two years later

On the Phenomenology of Tachyon Radiation

We present a brief overview of the different kinds of electromagnetic radiations expected to come from (or to be induced by) space-like sources (tachyons). New domains of radiation are here considered; and the possibility of experimental observation of tachyons via electromagnetic radiation is discussed