PBS Space Time (2015)

Something Disturbing Happens When You Solve Einstein's Equations This Way

Kurt Gödel discovered a solution to General Relativity that allows time travel without any exotic physics, revealing that the theory doesn’t actually guarantee a consistent chain of cause and effect . His “Gödel universe” shows that under certain conditions, the structure of spacetime itself can loop back on itself—blurring the line between past and future and exposing a deep limitation in our understanding of reality.