“After another two years of full thrust the ship would reach full speed, 98 percent 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.”
However, Hawking dismisses the prospect of time travel into the past. Some scientists have suggested this could be done by exploiting wormholes, gateways linking different parts of the universe or which provide a short-cut backwards or forwards through time. Theory suggests such wormholes do exist at the quantum scale, meaning they are far smaller even than atoms, so the challenge would be to enlarge them to a human scale.
But Hawking dismisses the idea, pointing out that time travel into the past would create the “mad scientist paradox” where a researcher could travel back in time and shoot his past self, raising the question of who could have fired the shot.
“This kind of time machine would violate a fundamental rule that cause comes before effect,” said Hawking. “I believe things cannot make themselves impossible. So it won’t be possible to travel back to the past, using wormholes or any other method.”
(Agencies)
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Stephen Hawking: stay away from aliens
BEIJING, April 27 (Xinhuanet) -- British astrophysicist Stephen Hawking claims in a new documentary that aliens do exist but humans should stay away from them, according to media reports Tuesday.
The physicist, 68, suggested that extraterrestrials exist not just on planets but also in many other parts of the universe, perhaps in the center of stars or even floating in space. Full story
