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.