Lorentzian traversable wormholes would enable travel in both directions from one part of deep space to another part of that same universe really rapidly or would enable travel from one universe to another. The possibility of traversable wormholes in general relativity was first shown in a 1973 paper by Homer Ellis and independently in a 1973 paper by K.
Bronnikov. Ellis examined the topology and the geodesics of the Ellis drainhole, revealing it to be geodesically complete, horizonless, singularity-free, and fully traversable in both instructions. The drainhole is an option manifold of Einstein's field formulas for a vacuum spacetime, customized by addition of a scalar field minimally combined to the Ricci tensor with antiorthodox polarity (negative rather of positive).
When m is set equivalent to 0, the drainhole's gravitational field vanishes. What is left is the Ellis wormhole, a nongravitating, simply geometric, traversable wormhole. Kip Thorne and his graduate trainee Mike Morris, unaware of the 1973 papers by Ellis and Bronnikov, manufactured, and in 1988 published, a duplicate of the Ellis wormhole for use as a tool for mentor basic relativity.
Later on, other types of traversable wormholes were discovered as allowable options to the equations of general relativity, consisting of a range evaluated in a 1989 paper by Matt Visser, in which a course through the wormhole can be made where the passing through course does not pass through an area of unique matter.
A type held open by negative mass cosmic strings was presented by Visser in partnership with Cramer et al., in which it was proposed that such wormholes could have been naturally developed in the early universe. https://paste2.org/VDxbLy5s link 2 points in spacetime, which implies that they would in principle allow travel in time, along with in area.
Nevertheless, according to general relativity, it would not be possible to use a wormhole to travel back to a time earlier than when the wormhole was first converted into a time "machine". Up until this time it could not have been noticed or have been used.: 504 Raychaudhuri's theorem and unique matter  To see why exotic matter is required, think about an inbound light front traveling along geodesics, which then crosses the wormhole and re-expands on the other side.