CNBC interviewers were thrown through a "Hyperloop" on Friday morning when billionaire mad-scientist Elon Musk said his idea for a futuristic transit concept could be built for "one-tenth of the cost" of California's current high-speed rail project.

The entrepreneur behind Tesla Motors and SpaceX did not elaborate on his description of the Hyperloop as a "cross between a Concorde, a railgun, and an air hockey table," which he teased at the Wall Street Journal's D11 conference. Musk says he might talk more about it after a June 20 Tesla-related announcement.

Business Insider reports that they've found RAND Corporation plans from 1972 that may be similar to Musk's "Hyperloop." That proposal includes "shooting electromagnetically levitated and propelled cars across the country in a vacuum sealed tunnel," they say.

Also in Friday's interview Musk denied dating Cameron Diaz. 

And said Tesla may partner with Google to make self-driving cars.

So, you know, that's all cleared up now.

The CNBC interview was live blogged. For visual types, here's a WSJ video from D11: