Elon Musk has made his name on big ideas, whether it’s space tourism or the electric car — but his latest project, mysteriously dubbed the Hyperloop, may be more revolutionary than anything he’s done. It started with a simple promise: the ability to travel from Los Angeles to San Francisco in half an hour. As time went on, Musk added more. It would be low-friction, and use such minimal power that the entire thing could be run on electricity from solar panels installed above the tracks. It would use small pods, leaving “whenever you arrive” instead of cleaving to a schedule like an airliner. He’s promised to unveil his alpha design for the project in just under a month’s time, but already, observers are speculating on exactly how this next-generation transportation scheme would work.