Some theoretical and experimental aspects of the tachyon problem

In this paper, the hypothetical existence of tachyons is re-examined. It has previously been doubted whether tachyons would exist, for it can be shown with the space-time diagram used in the Special Theory of Relativity that they are moving backward in time for some moving systems, and this would contradict the principle of causality. Some scientists tried to save the tachyon theory by using the so-called reinterpretation principle, but it is considered that this can be easily refuted. This paper shows that it can be concluded from the Einstein-Planck frequency relation and the de Broglie wave equation that the absolute value of the mass of the tachyons must be much lower than the rest mass of the electrons-nearly zero. But that means that they do not have any measurable energy if they move with a finite value aboutc. But if tachyons withv>c cannot be measured they cannot cause causality paradoxes. The low mass of the tachyons has also consequences for experimental search, and it will be shown that the previous search was doomed to failure. The limits of the photo-production cross-section for tachyons in lead can be given as 1.5·10^?32?σ<7·10^?31 cm². Further, it can be shown that the kinetic energy of the tachyons is identical to their total energy. We see that tachyons cannot be regarded as ‘faster than light particles’ — they are more a new kind of luxons. If they were to be uncharged it would be nearly impossible to distinguish them from this class of particles.