In 1948 Kurt Gödel found a particular solution for Einstein’s gravitational field equations regarding the rotation of the Universe.

Traveling through the space of such a universe, an astronaut can reach the past. In such a universe, light and things will be involved in the movement of rotation, which will allow material objects to follow a closed trajectory not only in space but also in time. There is no scientific evidence that our universe is in a state of rotation. However, the result obtained by Gödel showed that the theory of relativity does not exclude a movement back in time. Einstein himself was amazed by this result.

In Gödel’s conception, galaxies are not the only things in rotational motion. Galaxies rotate, and with them, space and time. If an expanding universe generates space and time, a rotating universe turns space and time around it in a spiral. In a rotating universe time travel becomes possible. By moving in a large enough circle around an axis, at a speed close to the speed of light, an observer could “catch” his temporal tail, returning to his starting point at a given moment before departure. The required paths are known as closed time curves (time loops).