I am sorry, Sir GeZe, but Einstein said Time Travel should not be possible. In Einstein’s Theory of Relativity, it states that nothing can go faster than the speed of light.
Einstein showed that was no such thing as instantaneous interaction in nature, but only a maximum possible speed of interaction. This is the speed of electromagnetic interaction, which is the speed of light or 300,000 kilometers per second. The second part of the Theory of Relativity states that the speed of light is universally constant and the same for all inertial observers no matter how they move.
As an object nears the speed of light, its relativistic mass increases until, at the speed of light, it becomes infinite. Accelerating an infinite mass any faster than that is impossible, or at least it seems to be right now. However, there is a mathematical possibility of particles that travel faster than the speed of light, called tachyons. There is mathematical evidence for this, though we have yet to detect any of them. Tachyons cannot slow down to below light speed, just as we cannot accelerate to above the speed of light. Perhaps, Herr F_alk could tell us more about this? :(