Tachyon – A Non-Existent Particle

In a 1967 paper [1], G. Feinberg conjectured about the possibility of “faster-than-light” particles. In the current note we prove his conjecture to be false by showing that he missed several key counter-arguments to their existence. We explain why the existence of tachyons contradicts both relativistic kinematics and relativistic dynamics. Our paper is divided in two sections: the kinematic counter-arguments and the dynamics counter-arguments.

Spacetime and Deformations of Special Relativistic Kinematics

A deformation of special relativistic kinematics (possible signal of a theory of quantum gravity at low energies) leads to a modification of the notion of spacetime. At the classical level, this modification is required when one considers a model including single- or multi-interaction processes, for which absolute locality in terms of canonical spacetime coordinates is lost. We discuss the different alternatives for observable effects in the propagation of a particle over very large distances that emerge from the new notion of spacetime. A central ingredient in the discussion is the cluster decomposition principle, which can be used to favor some alternatives over the others.

The ageing problem of twins in Reissner–Nordström spacetime

In this paper, we explore the effect of gravity on the flow of proper time near static spherically symmetric black hole possessing an electric charge. We use the Reissner–Nordström metric. In the first case, the traveling twin travels away from the black hole and in the second it travels toward it. We then compare it with the case of relativistic kinematics where the static twin ages faster than the traveling twin.