Parallel universes. Computer graphic illustration depicting two Earths and warped grids of spacetime. In the presence of extreme gravitational fields, spacetime may be distorted locally to form a singularity (point of infinite spacetime curvature). In order to account for the apparent 'disappearance' of matter in a singularity, it has been suggested by some writers that such singularities may be a 'gateway' into parallel universes. In all probability a parallel universe will not be remotely like ours, but the general idea has spawned a number of science fiction stories.