Wormholes

They’re a staple of science fiction, but could they be real? New research suggests wormholes could be somewhere around us, and we could uncover them

Reported by Ian Evenden

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We’ve all seen wormholes in science-fiction: openings in the very fabric of space through which spaceships can pass, opening up a method of faster-than-light travel in a universe that otherwise wouldn’t allow it. These shortcuts in space-time can be natural or human-made, and their exits can send you into other realms of normal space-time or into hyperspace, a set of higher dimensions laying closely alongside our own, but through which we can travel more quickly than in normal space. Their profusion in fiction might suggest they’re common.

In the set of dimensions we call reality, however, it’s not so easy. Wormholes have not been observed, and remain speculative. They’re consistent with Einstein’s theory of general relativity, which allows space-time to be distorted by gravity. Black holes are one such special solution to the equations, and wormholes are another. As we’ve only just got our first good look at a black hole, it’s entirely possible that wormholes could be out there somewhere, just waiting to be discovered.

“Wormholes are allowed in theory, and they have been intensely studied theoretically,” says Dr Andreea Font of the Astrophysics Research Institute at Liverpool John Moores University.

“They’re mostly regarded as theoretical curiosities, and we don’t actually have any tangible evidence of their existence.”

When Einstein and fellow physicist Nathan Rosen were working together at Princeton in the mid-1930s, they produced an idea of layers of folded space-time connected by ‘bridges’ we would today call wormholes. Another name for one type of wormhole is an Einstein-Rosen bridge in tribute to their work. All they required to create this idea was the complicated maths of general relativity and Maxwell’s equations, which cover electromagnetism. The pair would also go on to predict gravitational waves, but Einstein-Rosen bridges would be less of a success – they collapse so quickly nothing would ever be able to travel through them.

One problem with detecting a wormhole is telling it apart from a black hole. We just don’t know enough about either type to label one definitely as a wormhole, while the other is ‘merely’ a black hole. The existence of a one-way event horizon may be a clue that an object is a black hole, but again we’re in the world of pure theory. “We would like to know if there are any differences, but from the outside they may be indistinguishable,” says Font. “However, they both act on their surroundings through gravity, so there might be some telltale signs. Some scientists have suggested that a wormhole could perturb the orbits of stars nearby in a different way than a black hole would. Some gravity would leak out from the other side through the wormhole, changing the orbits of stars just enough to be noticeable.