Relativistic causality in particle detector models: Faster-than-light signaling and impossible measurements

José de Ramón; Maria Papageorgiou; Eduardo Martín-Martínez

doi:10.1103/physrevd.103.085002

Relativistic causality in particle detector models: Faster-than-light signaling and impossible measurements

Physical Review D ◽

10.1103/physrevd.103.085002 ◽

2021 ◽

Vol 103 (8) ◽

Author(s):

José de Ramón ◽

Maria Papageorgiou ◽

Eduardo Martín-Martínez

Keyword(s):

Light Signaling ◽

Particle Detector ◽

Relativistic Causality ◽

Faster Than Light

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SPECIAL RELATIVITY AND SUPERLUMINAL MOTIONS: A DISCUSSION OF SOME RECENT EXPERIMENTS

International Journal of Modern Physics A ◽

10.1142/s0217751x00001403 ◽

2000 ◽

Vol 15 (18) ◽

pp. 2793-2812 ◽

Cited By ~ 12

Author(s):

ERASMO RECAMI ◽

FLAVIO FONTANA ◽

ROBERTO GARAVAGLIA

Keyword(s):

Special Relativity ◽

Group Velocity ◽

Maxwell Equations ◽

Evanescent Waves ◽

Experimental Results ◽

Relativistic Causality ◽

Causal Paradox ◽

Faster Than Light

Some experiments, performed at Berkeley, Cologne, Florence, Vienna, Orsay and Rennes led to the claim that something seems to travel with a group velocity larger than the speed c of light in vacuum. Various other experimental results seem to point in the same direction: For instance, localized wavelet-type solutions of Maxwell equations have been found, both theoretically and experimentally, that travel with Superluminal speed. Even muonic and electronic neutrinos — it has been proposed — might be "tachyons," since their square mass appears to be negative. With regard to the first-mentioned experiments, it was very recently claimed by Guenter Nimtz that those results with evanescent waves or "tunneling photons" — implying Superluminal signal and impulse transmission — violate Einstein causality. In this note, on the contrary, we want to stress that all such results do not place relativistic causality in jeopardy, even if they refer to actual tachyonic motions: In fact, special relativity can cope even with Superluminal objects and waves. For instance, it is possible (at least in microphysics) to solve also the known causal paradoxes, devised for "faster than light" motion, even if this is not widely recognized. Here we show, in detail and rigorously, how to solve the oldest causal paradox, originally proposed by Tolman, which is the kernel of many further tachyon paradoxes. The key to the solution is a careful application of tachyon mechanics, as it unambiguously follows from special relativity.

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