Definition: A closed timelike curve (sometimes abbreviated CTC) is a theoretical solution to the general field equations of the theory of general relativity. In a closed timelike curve, the worldline of an object through spacetime follow a curious path where it eventually ends at the exact same coordinates in space and time that it began in. In other words, a closed timelike curve is the mathematical result that allows for time travel.
The first closed timelike curve was predicted in 1937 by Willem Jacob van Stockum, and was further elaborated on by the mathematician Kurt Godel in 1949. Normally, a closed timelike curve comes out of the equations through something called frame dragging, where a massive object or intense gravitational field moves and literally "drags" spacetime along with it. Many results that allow for a closed timelike curve involve a black hole, which allows for a singularity in the normally smooth fabric of spacetime, and often result in a wormhole.
Also Known As: CTC
