LOS ANGELES -- Imagine strapping into a car-sized capsule and hurtling through a tube at more than 700 mph -- not for the thrill of it, but to get where you need to go.
On Monday, billionaire entrepreneur Elon Musk unveiled a transportation concept that he said could whisk passengers the nearly 400 miles between Los Angeles and San Francisco in 30 minutes -- half the time it takes an airplane.
If it's ever built.
His "Hyperloop" system for travel between major cities is akin to the pneumatic tubes that transport capsules stuffed with paperwork in older buildings.
In this case, the cargo would be people, reclining for the ride.
The system would feature a large, nearly air-free tube. Inside, capsules would be pulled down the line by magnetic attraction.
Capsules would float on a cushion of air they create -- like an air hockey table in which the puck produces the air instead of the surface. To minimize friction from what air is in the tube, a powerful fan at the front of each capsule would suck air from the front to the rear.
"Short of figuring out real teleportation, which would of course be awesome (someone please do this), the only option for super fast travel is to build a tube over or under the ground that contains a special environment," Musk wrote in his proposal, posted online.
On a conference call Monday, Musk said that if all goes right, it could take seven to 10 years for the first passengers to make the journey between California's two biggest metro areas. He put the price tag at around $6 billion -- pointedly mentioning that would be about one-tenth the projected cost of a high-speed rail system that California has been planning to build.