Actually, Kurt Godel developed a solution to the Einstein equations which describe "closed timelike lines" in which it is possible to travel "back" in time without having to travel faster than the speed of light. He presented the solution in a paper to Einstein on the occasion of Einstein's 70th birthday (14 March, 1949). The paper extended relativity theory in [at that time] disturbing ways. In particular it suggests that Time is more like a spatial dimension (since you apparently can travel "through" it just like the familiar spatial dimensions) and furthermore that our perception of Time is subjective and that there is no notion of absolute time.
Actually, Kurt Godel developed a solution to the Einstein equations which describe “closed timelike lines” in which it is possible to travel “back” in time without having to travel faster than the speed of light.
_________________________________________________
I want to go back to an evening I spent with Maria Louisa Gonzalez Escobar in Mexico. Can you please forward me the equations?