It turns out that time travel to the past is actually relatively easy. All you have to do is spin the universe. Famous mathematician Kurt Gödel was Albert Einstein’s friend and neighbor at Princeton. He was deeply involved with Einstein’s general theory of relativity, which is and still is our modern formulation of gravity. This theory attributes the existence of matter and energy to the bending and bending of space and time, and then attributes this bending and bending to the behavior of matter and energy.

Gödel wondered whether the theory of relativity would allow time travel into the past. Einstein’s theory was intended to be the ultimate basis for the nature of space and time, and time travel to the past is prohibited as far as we know. So Gödel believed that general relativity should automatically reject this.

And Gödel actually found that general relativity is perfect for traveling into the past. The trick is to set the universe in motion. Gödel created a relatively simple artificial model of the universe to prove his point. This universe rotates and contains only one component. This component is a negative cosmological constant that opposes the centrifugal force to keep the universe static.

Gödel discovered that if you follow a certain path in this spinning universe, you can arrive at your own past. You’d have to travel incredibly far, like billions of light years, to do this, but it’s possible. As you travel, you will be immersed in the rotation of the universe. This is not just the spin of matter in space, but also space and time itself. Essentially, the rotation of the universe will change your potential paths so much that they will return to where you started.

You continue your journey and never go faster than the speed of light and you’re back where you started, but in your own past. The possibility of backward time travel creates paradoxes and distorts our understanding of causality. Fortunately, all observations show that the universe does not rotate, so we got rid of Gödel’s problem of backwards time travel. But why general relativity agrees with this seemingly impossible phenomenon is still a mystery. Gödel used the example of the rotating universe to argue that general relativity is incomplete and may be right.