Source: Science Focus

In 1935, Albert Einstein and his colleague Nathan Rosen showed that black holes can theoretically be connected via ‘wormholes’ – shortcuts through space and time that could link up black holes light-years apart.

To create a wormhole on Earth, we’d first need a black hole. This is problematic: creating a black hole just a centimetre across would require crushing a mass roughly equal to that of the Earth down to this tiny size. Plus, in the 1960s theorists showed that wormholes would be incredibly unstable.

It could be possible to stabilise the wormhole using so-called ‘exotic matter’, whose existence is predicted by quantum theory. This weird stuff is expected to have an antigravitational effect, which could stop the wormhole collapsing. But no one has a clue how to do any of this. And even if they did, it might all be pointless: theorists now suspect that travelling via wormholes would actually take longer than simply taking the conventional route through space.