## Comment: Momentum of tachyon traveling at infinite speed (Score 1) 142

One of the strange things about a tachyon is that it can be traveling in one direction for some real inertial reference frame, and be traveling in another direction for some other inertial reference frame. For yet another reference frame intermediate between those two, the tachyon is traveling at infinite speed, yet has zero dynamic mass and a finite momentum of +/- *i* mc, where *i* is the square root of -1, m is the imaginary rest mass of the tachyon, and c is the speed of light.

The direction of the momentum vector is ambiguous.

Since this is a total contradiction, I assume that tachyons cannot exist.