Stephen Hawking puts his money on time travel

HUMANS may one day be able to travel generations into the future, Stephen Hawking says.

He suggests humans could build spaceships capable of such high speeds that time would slow down for those on board. Such a spaceship could travel thousands of years into the future, reaching distant star systems within the lifetime of the crew.

“Time travel was once considered scientific heresy and I used to avoid talking about it for fear of being labelled a crank, but these days I’m not so cautious,” Professor Hawking says in Stephen Hawking’s Universe, to air in Britain on Sunday.

Professor Hawking suggests humanity could build a giant “relativistic” spaceship, so called because it would exploit the science set out by Albert Einstein in his theories of relativity.

Einstein found that as objects accelerate through space, the rate at which time passes for them slows down. For objects such as cars and aircraft the effect is negligible, but Professor Hawking’s spaceship would exceed 98 per cent of the speed of light, when such effects would be extremely powerful.

Professor Hawking said such a ship could theoretically reach speeds of more than 1000 million km/h but would have to be built on a huge scale simply to carry all the fuel that would be needed.

“After the first two years it would reach half light speed and be far outside the solar system. After another two years it would be travelling at 90 per cent of the speed of light,” he said.

“After another two years of full thrust the ship would reach full speed, 98 per cent of the speed of light, and each day on the ship would be a year on Earth. At such speeds a trip to the edge of the galaxy would take just 80 years for those on board.”

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