Garth Powell, of Dunedin, asks :-

Could you tell me about wormholes in space? They sound fascinating for time travel etc.

Jenni Adams, a theoretical physicist at the University of Canterbury, responded.

Before I say anything about wormholes perhaps it would be a good idea to say a little bit about Einstein's famous Theory of General Relativity. Einstein proposed that mass makes space and time curve. To get a picture of this, imagine a stretched sheet of rubber with a heavy weight in the middle of it. Around the weight the rubber sheet will be distorted. Einstein said that massive objects would distort space and time in a similar way so that mass can make objects appear longer and time to go slower!

A wormhole is a possible solution to Einstein's equations. It is, as its name suggests, a tunnel in space and time. The fact that a wormhole agrees with Einstein's theory means that theoretically they are allowed to exist and their existence is not in contradiction with any known physical principle. On the other hand we have not observed anything which even hints at the actual presence of a wormhole.

Theoretically a wormhole could link vast distances in the Universe and allow time travel. However as wormholes would be associated with very strong gravitational forces and perhaps creation of highly energetic particles, it does not seem likely that a human could travel through a wormhole. In fact since we have not observed time travellers we should probably assume that humans will never, in the future, use wormholes for time travel!

Nevertheless wormholes are fascinating objects and until we understand them further we cannot be sure of their capabilities.