Time travel is a tricky thing. Einstein's math does not preclude it, but it has not, as yet, given us an easy way to do it. We can travel into the future by traveling at faster-than-light speeds. For us, time will slow, and for the place of our departure, it will continue. When we return, we will return to our future. Travel into the past, that's a bit more dicey. Will I change things? Enigmas like the Grandfather paradox (Can I go back and kill...