The “cross between Concorde, a rail gun and an air hockey table” will deliver passengers between US cities faster than the speed of sound. The history of transport is replete with dreamers who have concocted such schemes for getting people from A to B in previously unimagined haste. And many of them have remained just that, impractical ideas on a drawing board that will never see the light of day. But the latest mysterious project, which has had the technology world buzzing for months, has one crucial difference. Its backer is a Silicon Valley wunderkind with a proven track record of turning science fiction into reality. Billionaire Elon Musk’s CV is impressive, to say the least. He made his initial fortune from PayPal, the online secure payment system, before going on to launch spaceships. Last year his SpaceX venture became the first private operation to dock a cargo capsule with the International Space Station. Back on Earth, Mr Musk also founded Tesla, which has made electric sports cars viable and profitable. The mercurial, fictional character of Tony Stark, played by Robert Downey Jr in the Iron Man films, is reputedly based on him. So when Mr Musk, 42, announced that he would be publishing plans for the Hyperloop on Monday, August 12 - tomorrow - scientists were sent into a tailspin.