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 a friend and neighbor of Albert Einstein at Princeton. He became incredibly curious about Einstein’s theory of general relativity, which was and continues to be our modern formulation of gravitational force.
This theory relates the presence of matter and energy to the bending and warping of space and time, and then relates this bending and warping to the behavior of matter and energy.
Gödel was curious if relativity could allow time travel to the past. Einstein’s theory claimed to be an ultimate framework for the nature of space and time, and as far as we know, time travel to the past is forbidden. Gödel therefore felt that general relativity should automatically forbid it.
And Gödel discovered that in reality general relativity is perfectly compatible with time travel in the past. The trick is to set the universe in motion.
Gödel constructed a relatively simple and artificial model universe to prove his point. This universe is in rotation and contains only one ingredient. This ingredient is a negative cosmological constant that resists the centrifugal force of rotation to keep the universe static.
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Gödel discovered that if you follow a particular path in this rotating universe, you can find yourself in your own past. You would have to travel incredibly far, billions of light years long, to do it, but it can be done.
As you travel, you would be caught up in the rotation of the universe. It’s not just a rotation of things in the cosmos, but of space and time themselves. Essentially, the rotation of the universe would alter your potential paths forward so drastically that those paths would return to where you started.
You would set out on your journey and never travel faster than the speed of light, and you would find yourself back where you started but in your own past.
The possibility of backward time travel creates paradoxes and violates our understanding of causation. Fortunately, all observations indicate that the universe is not rotating, so we are protected from Gödel’s problem of backward time travel.
But it remains to this day a mystery why general relativity agrees with this seemingly impossible phenomenon. Gödel used the example of the spinning universe to assert that general relativity is incomplete, and he may still be right.
This article was originally published by Universe Today. Read the original article.