A wormhole is a hypothetical tunnel that shortens the path between distant corners of the universe, like a soap bubble stretched between two points. To keep the bubble's walls from closing, a special film is needed — matter with negative pressure, akin to dark energy. But this support isn't eternal: remove half the film, and the bubble bursts.
Physicists tested this scenario on a computer. They simulated how, as the support weakens, the wormhole collapses, giving birth to a black hole. Meanwhile, the swallowed matter doesn't vanish without a trace: it's ejected back in a powerful burst, like spray from a burst balloon. The disturbance ripples through space as gravitational waves, racing at the speed of light.
A signal from a wormhole of a thousand solar masses, a million light-years away, is still too faint for today's detectors. But future gravitational antennas like the Einstein Telescope will be able to catch this "echo." And then we will hear how, for a moment, space turns into a punctured bubble.
The term 'wormhole' was coined by physicist John Wheeler in 1957, though the idea itself traces back to Einstein and Rosen.
In 'Interstellar,' the wormhole near Saturn was held open by invisible matter. Remove it, and the tunnel would collapse, just as in the physicists' models.