wormhole

A wormhole is a hypothetical tunnel in spacetime that connects two distant regions, potentially allowing shortcuts between far-apart places or even between different times. In general relativity, wormholes appear as solutions to Einstein's field equations. The simplest is the Schwarzschild wormhole (Einstein–Rosen bridge), which joins two asymptotically flat regions but is non-traversable because the throat pinches off too quickly.

Traversable wormholes were proposed by Morris and Thorne. They would require exotic matter with negative energy density to keep the throat open and yield tolerable tidal forces. Such matter violates classical energy conditions and remains speculative.

If traversable, wormholes could in principle enable time-like paths, but this involves causality concerns and is compatible only with speculative physics and conjectures such as Hawking’s chronology protection.

Currently there is no observational evidence for wormholes. They are a theoretical topic in general relativity and quantum gravity, used to probe spacetime topology, energy conditions, and the limits of traversable geometry.