Time travel into the past may be possible, according to mathematician Kurt Gödel. Gödel, who was friends with Albert Einstein, studied Einstein’s General Theory of Relativity and wondered if it allowed for time travel. The theory explains how matter and energy can bend and warp space and time. Gödel believed that if time travel was possible, it should be forbidden by General Relativity.
However, Gödel found that General Relativity is actually okay with time travel into the past. He created a model universe that was rotating and had a negative cosmological constant. He discovered that if you followed a certain path in this rotating universe, you could end up in your own past. This would require traveling billions of light years, but it could be done. The rotation of the universe would change your potential paths forward and loop you back to where you started.
While this idea of backwards time travel creates paradoxes and goes against our understanding of causality, it’s important to note that the universe doesn’t seem to be rotating. Gödel’s discovery raises questions about the completeness of General Relativity.