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Time travel possible, Hawking concedes

LONDON - Professor Stephen Hawking, one of the world's top cosmic physicists, has accepted the possibility of time travel - an idea he had dismissed for years.

"If you combine Einstein's General Theory of Relativity with quantum theory it does begin to seem a possibility," he was quoted as saying by Britain's Sunday Times newspaper.

But the Cambridge University mathematics professor added that he still thought it would probably never be practical.

Prof Hawking previously ridiculed the idea, basing his argument on science and ordinary logic and saying something which could let you kill your ancestors or alter your past was unthinkable.

"The best evidence that time travel will never be possible is that we have not been invaded by hordes of tourists from the future," he said two years ago.

But he spells out his change of heart in a foreword for The Physics Of Star Trek, a book by US astronomer Lawrence Krauss which is to be published next month,  saying: "One of the consequences of rapid interstellar travel would be that one could also travel back in time."

Einstein's belief that time and space were closely related and were both affected by gravity sparked speculation that time travel could be possible, a view an increasing number of astronomers and physicists have signed up to in recent years.

"His theories led to the idea that enormous gravitational fields, such as those found around collapsed stars known as black holes, could reverse the flow of time," the Sunday Times said.

However, harnessing enough energy for a machine to send travelers back through time would pose a major problem. - Reuter.