In 1949, as a birthday present for Einstein, Gödel developed a solution that would permit timelike curves. He specifically designed it this way to make travel into the past possible. This led physicists to assume that timelike curves were a kooky artifact of unrealistic solutions to general relativity. Wormholes as a Time MachineThe possible existence of closed timelike curves raises many questions. “It seems there is a chronology protection agency, which prevents the appearance of closed timelike curves and so makes the universe safe for historians,” he wrote.