SPACE is big," wrote Douglas Adams in his book The Hitchhiker's Guide to the Galaxy. "You just won't believe how vastly, hugely, mind-bogglingly big it is."
He wasn't exaggerating. Even our nearest star Proxima Centauri is a staggering 4.2 light years away - more than 200,000 times the distance from the Earth to the sun. Or, if you like, the equivalent of 50 million trips to the moon and back.
Such vast distances would seem to put the stars far beyond the reach of human explorers. Suppose we had been able to hitch a ride on NASA's Voyager 1 the fastest interstellar space probe built to date. Voyager 1 is now heading out of the solar system at about 17 kilometres per second. At this rate it would take 74,000 years to reach Proxima Centauri - safe to say we wouldn't be around to enjoy the view.
So what would it take for humans to reach the stars within a lifetime? For a start, we would need a spacecraft that can rush through the cosmos at close to the speed of light. There has been no shortage of proposals: vehicles propelled by repeated blasts from hydrogen bombs, or from the annihilation of matter and antimatter. Others resemble vast sailing ships with giant reflective sails, pushed along by laser beams.
All these ambitious schemes have their shortcomings and it is doubtful they could really go the distance. Now there are two radical new possibilities on the table that might just enable us - or rather our distant descendants - to reach the stars. read the rest of the article...
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