A note on a new paradox in superluminal signalling

TL;DR

This paper clarifies that one-way superluminal signals do not violate causality, countering recent suggestions of a paradox, and emphasizes the robustness of causality in special relativity.

Contribution

It demonstrates that one-way faster-than-light signaling cannot lead to causality violations, correcting recent misconceptions about superluminal communication.

Findings

One-way superluminal signals do not cause causality violations.

The traditional two-way Tolman paradox remains the primary causality concern.

Superluminal particles and signals are consistent with causality principles.

Abstract

The Tolman paradox is well known as a base for demonstrating the causality violation by faster-than-light signals within special relativity. It is constructed using a two-way exchange of faster-than-light signals between two inertial observers who are in a relative motion receding one from another. Recently a one-way superluminal signalling arrangement was suggested as a possible construction of a causal paradox. In this note we show that this suggestion is not correct, and no causality principle violation can occur in any one-way signalling by the use of faster-than-light particles and signals.