After much speculation, entrepreneur Elon Musk on Monday unveiled his plans for a $6 billion, super-fast "Hyperloop," which would ideally be able to transport travelers between Los Angeles and San Francisco in 30 minutes.

Musk laid out a plan that includes a series of tubes, pylons, and passenger capsules that are propelled via air cushions. It's all in the very early planning stages – you might not be able to slide into a Hyperloop capsule for another decade – but you have to start somewhere. To that end, Musk said he will probably craft a demonstration version of the Hyperloop before handing it over to someone else, since he is rather busy with Tesla Motors and SpaceX.

Musk had little over a dozen people from Tesla and SpaceX working on the project as a "background" task; "it wasn't anybody's full-time job," he said. That includes members of the SpaceX and Tesla aero-dynamics team and the Tesla motor group.

They considered a number of approaches, including the pneumatic tubes used to send mail and packages in large buildings. "However, the friction of a 350 mile long column of air moving at anywhere near sonic velocity against the inside of the tube is so stupendously high that this is impossible for all practical purposes," Musk said yesterday.

A vacuum approach, meanwhile, is hard to maintain in a single room, "let alone 700 miles (round trip) of large tube with dozens of station gateways and thousands of pods entering and exiting every day," he said.

As a result, Musk proposed mounting "an electric compressor fan on the nose of the pod that actively transfers high pressure air from the front to the rear of the vessel. This is like having a pump in the head of the syringe actively relieving pressure."

What would this actually look like? In his outline of the project, Musk included a few mock-ups and diagrams. To see what he has in mind, check out the slideshow.