Like that bullet train, the Hyperloop didn't take long to attract skepticism.
Citing barriers such as mountains and cost, one transportation expert said that while Musk's idea is novel, it's not a breakthrough.
"I don't think it will provide the alternative that he's looking for," said James E. Moore II, director of the transportation engineering program at the University of Southern California.
Monday's unveiling lived up to the hype part of its name.
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.
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 the rocket-building company SpaceX.
Musk has said he is too focused on other projects to consider actually building the Hyperloop, and instead would publish an open-source design that anyone can use or modify.
That's still the case, he said Monday, but added that if no one else steps forward he might build a working prototype. That would take three or four years, he said.
AP National Writer Martha Mendoza contributed to this report from San Jose, Calif.