We have all watched movies that deal with the subject of time travel. Most of the time, such movies use an exotic element of physics, such as wormholes, faster-than-light speed (warp drives) and other similar mechanics. There are a huge number of movies on the subject with ‘Back to the Future’, really standing out as the perfect flick. But our current understanding of physics does not support any of these elements as viable methods of time travel. However, there is one theory that has not been disproven by science and it is probably the only way this science fiction can exist, albeit it would limit us to only time travel to the past. And that is the theory of a rotating universe, given by the mathematician Kurt Godel in 1949. Let’s take a closer look at how time travel would work as per this theory.
Kurt Godel was a logician, mathematician, and philosopher. And one of the notable works of his life was the formulation of a rotating universe. To describe this universe, he used the language from Albert Einstein’s theory of general relativity. The main purpose of this theory was to highlight that general relativity was not complete in itself and there were gaps that this parallel theory could fill in.
Time travel and rotating universe
Let’s take a closer look at this theory. The theory spoke of a universe which was rotating, much like our planets rotate along its axis. It deviates from our current understanding of the universe where we believe that it is expanding and planets, solar systems and even galaxies are constantly in motion.
However, in Godel’s theorem, the universe, instead of moving, keeps rotating. He also imagines a negative constant that resists the centrifugal force to keep the universe static. Now, in this world, if you were standing still at one point, you could theoretically see galaxies and stars moving in the sky. In fact, you could leave the Earth and be in space and you would still see everything rotating around you.
But this would also mean, the farther you were from a celestial object, the faster it would appear to spin. And this is a rotation of space-time itself. So, light itself would be moving in curves to reach an observer. This curvature of light would also mean that it will take longer for information to come from larger distances compared to the closer ones. Extending the logic would also mean that at some point, light would completely curve and go back to the observer if they tried looking beyond a certain point. In theory, it means, an observer could take a telescope and see reflective images of our world in it, just with things in the past.
And if you applied the same logic to an object and sent them far away in space, they too would get caught up in the rotation and return to their starting point. But they would find that they returned to a point earlier than they left. So, in short, they time traveled to the past.
Interestingly, while there is no proof of an universe which displays such characteristics, in our knowledge of physics, nothing stops such a universe from existing either. It’s just that we have not found such a universe so far. So, in reality, it is still, just a theory.