The Foundation series is typical in that to travel at faster than light speeds, you must enter another type of galaxy, called G^h, which stands for GALAXY^hyperspatial. Hyperspatially, the galaxy is a nondimensional dot and there are no relativistic effects at all (the warping of time/space created by approaching the speed of light). Speed does not really have a meaning in G^h. Hyperspacially, the value of all speed is zero, you do not move; with reference to space itself, your speed is infinite. "I can't explain things a bit more than that," says Golen Trevize, the main character of the last two books in the Foundation series. The symbol for the relativistic galaxy, the one we all know and love so well, is G^r. It is important to note that Einstein's special theory of relativity has not been disproven in Foundation, they have only found a loophole.