Update: Elon Musk has released his proposed "hyperloop" plans. One is tempted to describe them as the rantings of a madman who has seen a little bit too much of "The Jetsons" except, you know, the dude's track record is pretty impressive, to say the least. Musk is the founder of SpaceX and the co-founder of Tesla Motors and PayPal. AP is describing the basic concept behind his idea as traveling between major metropolitan areas using "a large tube. Inside, capsules would float on air, traveling at over 700 mph. The air would be sucked by a powerful fan at the front and expelled at the rear."

Businessweek has posted an interview with Musk explaining the physics behind the proposal and answering some of the skeptics.

High-speed rail critics will be delighted to read that Musk starts his proposal by dissing that project. "How could it be that the home of Silicon Valley and JPL --doing incredible things like indexing all the world's knowledge and putting rovers on Mars -- would build a bullet train that is both one of the most expensive per mile and one of the slowest in the world?" he writes. "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."

However, "this is where things get tricky," he says.

No kidding.

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Musk spoke on a conference call today to the media. KPCC's Ben Bergman tweeted the call...

Musk says it would take 7-10 years for the Hyperloop to become fully operational... about how long it would take to build high speed rail

— Ben Bergman (@thebenbergman) August 12, 2013

Here is the full audio from that call ...

Here's AP's write-up of Musk's release of his design plans.

LOS ANGELES (AP) — Imagine stepping into a car-sized capsule in downtown Los Angeles and, 30 minutes later, emerging in San Francisco.

On Monday, billionaire entrepreneur Elon Musk unveiled a transportation concept that he said could whisk passengers the nearly 400 miles from Los Angeles to 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 would use a large tube. Inside, capsules would float on air, traveling at over 700 mph. The air would be sucked by a powerful fan at the front and expelled at 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.

The system Musk envisions is not unlike the pneumatic tubes that transport capsules stuffed with paperwork in older buildings.

In this case, the cargo would be several people, reclining for the ride.

Coming from almost anyone else, the hyperbole would be hard to take seriously. But Musk has a track record of success. He co-founded online payment service PayPal, electric luxury carmaker Tesla Motors Inc. and rocket-building company SpaceX.

Monday's unveiling lived up to the hype part of its name.

Leading up to the unveiling, done on the SpaceX website, online speculation was feverish. Musk has been dropping hints about his system for more than a year during public events, mentioning that it could never crash and would be immune to weather.

During a Tesla earnings call Thursday, Musk said he is too focused on other projects to consider actually building the Hyperloop.

"I think I kind of shot myself by ever mentioning the Hyperloop," he said. "I don't have any plans to execute, because I must remain focused on SpaceX and Tesla."

He said he would fulfill his commitment to publishing an open-source design, meaning anyone can use it and modify it.

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San Francisco to Los Angeles in Half Hour? Read Elon Musk's Design Proposal for 'Hyperloop'