Tachyon is a hypothetical particle traveling faster than light.http://en.wikipedia.org/wiki/Tachyon In Cramer's Transactional Interpretation there is a field of standing waves created by interacting wave functions. The wave function doesn't exist separable as an alone wave function. We observe it always as an interaction of 2 or more wave functions. If there are more wave functions interacting the particle is better defined and uncertainty decreases. If the wave function doesn't exist separable but it appears in different interactions as a nonlocal information about the oscillation of the particle so it has to move immediatelly between the points of the interaction. That way there isn't a quantum jump. Tha wave functions appears in different interactions immediatelly. The interactions needs time only. There is an assumption that a wave function from Cramer's TI of QM may be something like tachyon. Tachyon = wave function = informationhttp://cramerti.home.pl/ We observe speed of light (photon) in the Vacuum. It isn't an empty space. There is a field of interactions of the wave functions (tachyons).In a perfect empty space an information may move immediatelly. Where is that empty space ? we don't observe it in our Observable Universe.