STEPHEN HAWKING: How to build a time machine
By STEPHEN HAWKING Created: 18:47 GMT, 27 April 2010 All you need is a wormhole, the Large Hadron Collider or a rocket that goes really, really fast 'Through the wormhole, the scientist can see himself as he was one minute ago. But what if our scientist uses the wormhole to shoot his earlier self? He's now dead. Hello. Time travel was once considered scientific heresy. To see how this might be possible, we need to look at time as physicists do - at the fourth dimension. But there is another kind of length, a length in time. To see what that means, let's imagine we're doing a bit of normal, everyday car travel. Let's indulge in a little science fiction for a moment. Physicists have been thinking about tunnels in time too, but we come at it from a different angle. Enlarge Nothing is flat or solid. Unfortunately, these real-life time tunnels are just a billion-trillion-trillionths of a centimetre across. The fastest manned vehicle in history was Apollo 10. Paradoxes are fun to think about.