Ever since a trip through a wormhole was first portrayed in 2001: A Space Odyssey 50 years ago, the idea of them has captured the public imagination. And small wonder: they’re the ultimate form of cosmic travel: a way of zipping across galaxies in an instant.
But while wormholes have become a staple of science fiction, among scientists they’ve been a source of endless frustration. Not because the idea is ridiculous, but because it isn’t. The astonishing fact is that wormholes are a natural consequence of current theories of gravity, and were investigated by Einstein himself over 80 years ago. Ever since, researchers have been trying to find out if such a bizarre theoretical possibility could be a reality.
And now they have made a major breakthrough – one which exploits deep connections between the nature of space and time and the laws of the subatomic world. The result is a new understanding of exactly what’s required to make a real-life wormhole.
Einstein first investigated the properties of wormholes with his colleague Nathan Rosen in 1935, using his theory of gravity known as General Relativity. They found that what we now call a black hole could be connected to another via a tube-like ‘throat’. Now called the Einstein-Rosen bridge, this seemed to open the way to taking shortcuts through space and time, entering a black hole in one part of the Universe and emerging from another perhaps millions of light-years away, but without taking millions of years to do so – thus effectively travelling faster than the speed of light.
It was a stunning idea, but in the early 1960s it was dealt a severe blow by John Wheeler, the brilliant US physicist who first coined the terms ‘black hole’ and ‘wormhole’. Together with fellow theorist Robert Fuller, he showed that the Einstein-Rosen bridge would collapse almost as soon as it formed. As Dr Daniel Jafferis, associate professor of physics at Harvard University explains: “We could jump in from opposite sides and meet in the connected interior, but then we would both be doomed.”
Jafferis is one of an elite group of theorists around the world searching for ways to dodge this problem. For years, the most promising idea has been to support the bridge using a type of ‘exotic matter’ with negative energy. As its name suggests, this is pretty weird stuff – so weird it’s capable of bending the normal rules of gravity. While ordinary matter always generates a gravitational pull, the negative energy produced by this exotic matter generates an antigravitational repulsion. Amazingly, such energy is known to exist. In the 1990s, astronomers discovered that the whole Universe is expanding under the antigravitational effect of so-called ‘dark energy’. There’s just one problem – the exact origins of dark energy are as yet unknown. The same goes for the exotic matter – no one has any idea how to create the stuff, let alone use it keep a wormhole open long enough to fly through.
The worm has turned
But now the debate over such so-called traversable wormholes has taken a radical new turn. It follows the discovery of a new…
This is an extract from issue 322 of BBC Focus magazine.
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