Travelling through time may not be the far-fetched science fiction theory it was once thought to be, according to Professor Brian Cox. Speaking at the British Science Festival, Cox declared to the audience: ‘Can you build a time machine? The answer is yes.’ However, the theory only works when travelling to the future, and Cox explained that once in the future it’s not possible to come back. Professor Cox is set to give a scientific talk on the theory of time travel to mark the 50th anniversary of Doctor Who in London next week. The talk will form part of a set of anniversary shows that will be shown before the BBC’s Day of Doctor episode on 23 November. During his speech at the Birmingham-based science festival, Cox said time travel has already been done, on a very small scale. He added that if the technology was developed to accelerate larger objects, it could be possible for humans to travel to the future, similar to Doctor Who’s Tardis in the TV show. Yet this technology doesn’t exist yet, and will never exist that could take people to the past. ‘You can go into the future; you’ve got almost total freedom of movement in the future,’ said Cox. This means that Marty McFly in Back to the Future science fiction film trilogy could have travelled to 2015. However, he wouldn’t have been able to return to 1985, or travel back to 1955 like he does in the first film. ‘If you go fast, your clock runs slow relative to people who are still. ‘As you approach the speed of light, your clock runs so slow you could come back 10,000 years in the future.’ The theory is based on Einstein’s Theory of Special Relatively that states to travel forward in time, an object would need to reach speeds close to the speed of light. As an object approach these speeds, time slows down but only for that specific object travelling. For example, people flying over the Atlantic will experience time passing marginally slower than people on the ground. ‘In General Relativity, you can do it in principle,’ continued Cox. ‘It’s to do with building these things called wormholes; shortcuts through space and time. But most physicists doubt it.
