Kurt Godel and Time Travel

We all know the man on the right — that’s Albert Einstein, the most famous scientist of the 20th century. But to his left is another important scientist, Kurt Gödel, a mathematician so brilliant that Einstein said that he used to come to the Institute of Advanced Study at Princeton just “to have the privilege to be able to walk home with Gödel.” The two geniuses had such a close intellectual friendship that when Einstein turned 70, Gödel gave him a birthday present in the form of an article: “An example of a new type of cosmological solutions of Einstein’s field equations of gravitation”. The paper’s proposals still have scholars debating, and no wonder: it posited the possibility of time travel.

The math worked out, and still satisfied Einstein’s theories of relativity, according to Gödel, if the universe were rotating, and also, if there were a way that the universe was resisting the centrifugal force of the rotation to keep itself static. In this situation, there would be closed-loop time-like paths, and even though it might take umpteen-billions of years, eventually these paths would loop around to where they had already been.

Gödel’s gift to his friend certainly probed some intriguing aspects of Einstein’s theories, but the logician thought the time-travel “grandfather paradox” (you go back in time and kill your grandfather before he had children, so you were never conceived and therefore couldn’t kill your grandfather) would never be practically able to happen. And scientists don’t have evidence that the universe is rotating. But I think it is fascinating that Gödel’s mathematical hypothesis is still taken seriously.