A wormhole is a solution of general relativity in which two separate regions of spacetime are connected by a throat. Unlike a black hole it has no event horizon, so in principle something could pass through and come back.

No wormhole has ever been observed, and none is known to exist. The geometry is a valid solution of Einstein's equations, but holding a throat open requires exotic matter with negative energy density in quantities nobody has produced or detected.

What is the difference between a wormhole and a black hole?

A black hole has a one-way horizon and a singularity; anything crossing in cannot return. A traversable wormhole has neither — it is a tunnel, and light passing through it emerges somewhere else rather than being trapped.

Could a wormhole be used for time travel?

In principle. If the two mouths are moved relative to each other at different speeds, time dilation desynchronises them and the tunnel connects two different times as well as two places. Whether physics permits the resulting causal loops is unresolved.

Что такое Wormhole?

A wormhole is a tunnel through spacetime: two distant regions joined by a shortcut that does not pass through the space between them. Unlike a black hole it has no horizon and no singularity — light and matter can go in one side and come out the other.

The idea is as old as general relativity itself. Einstein and Nathan Rosen found the first version in 1935 while trying to describe particles as features of geometry rather than as things sitting in it; the "Einstein-Rosen bridge" turned out to connect two exterior regions through the middle of a black hole. That version is useless for travel — it pinches off faster than anything can cross. Making one that stays open, which is what Kip Thorne and Michael Morris worked out in 1988, requires threading the throat with matter of negative energy density. Nothing like that has ever been observed in the quantities needed. The geometry is legitimate general relativity; the plumbing is the problem.

What makes a wormhole worth rendering is that it is not a hole at all, and every intuition trained on black holes is wrong here. There is no shadow. Rays whose angular momentum is smaller than the throat radius do not fall in and stop — they go through and keep going in a second universe, so the middle of the frame is a round porthole with a completely different sky behind it. Rays that very nearly threaded the throat wind around it and come back, which is what draws the bright ring outlining the window.

This scene integrates the exact Ellis-Bronnikov geodesic equation rather than approximating the look of one. The metric is spherically symmetric, so every ray stays in a single plane and the whole three-dimensional problem collapses to two ordinary differential equations, marched per pixel. The far sky is not a texture, not a cube map and not a composite: it is a second procedural starfield sampled by the direction each ray is actually travelling after it emerges — which is why the view through the throat swings the way a window does when you orbit it, and not the way a decal does.