What are wormholes?

04 August 2015

Question

What are wormholes and how are they created in the universe?

Answer

James Farr investigates with Harvey Reall, theoretical physicist from Cambridge University...

James - What are wormholes and how are they created in the universe? A wriggly one indeed. So what are wormholes? Are they science fact, or science fiction. When I put it to you on Facebook I had a very mixed response. Well Paul, and Miles Hendrik's both voted for fiction, David Horne suggested that they're "celestial temples, where godlike aliens live" - An interesting thought, but general consensus seems to suggest that they could be some kind of short cut across the universe. So does this mean you could jet off to an alien planet through one for your summer holidays? I think it's time to get an expert involved. Harvey Reall is a professor of theoretical physics at the University of Cambridge. Hopefully he can help us blast off from space and time to find a solution...

Harvey - A wormhole is a hypothetical shortcut between two seemingly distant points in space; the possibility of wormholes is motivated by general relativity, Einstein's theory of gravity, which is one hundred years old this year. In general relativity, space and time are not described by the geometry that we were taught in school. Instead they're combined to form a four-dimensional entity known as space time.

James - While in day to day life it's okay to consider three dimensional space, and one dimensional time, as completely separate concepts, Einstein's stroke of genius was to see that, when we're thinking on the scale of stars or galaxies, they are inseparably intertwined with each other. He came up with the idea of spacetime, often referred to as the "fabric of the universe". The force of gravity is produced by this spacetime being curved. To imagine this, think of a bowling ball and some marbles placed on a trampoline. The bowling ball makes the trampoline sag downwards and so the marbles roll towards it. Now, back to worm holes...

Harvey - Unfortunately, worm holes tend to be unstable and collapse to form black holes. This happens so fast that it would be impossible to travel across the wormhole, even at the speed of light. To overcome this problem you would have to build the wormhole using exotic matter.

James - While we've never seen this kind of matter, we know that it would produce an anti-gravity like effect, pushing things away from it rather than pulling them in. This would then be able to force a wormhole open and stop it from collapsing in on itself. Unfortunately though to make a wormhole big enough to travel through, you would need a lot of this exotic matter: to make a wormhole the size of a grapefruit, current estimates say that we would need to use the same amount of energy that our sun produces over one hundred million years.

Harvey - Therefore it seems very unlikely that wormholes could have formed naturally in our universe, or that an advanced civilisation could make one.

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