Some of the world’s brightest minds have speculated that a vacuum tube is the only way to do it — but before that idea could even get off the ground, Musk said that the Hyperloop is not based on an evacuated tunnel. With that possibility ruled out, there aren’t actually that many ways of safely and economically propelling carriages at 700 mph (1126 kph). Furthermore, when you factor in Musk’s comments that the Hyperloop “can never crash,” has no need for rails, and is “immune to weather,” the architecture of the system becomes a real head-scratcher. Oh, did I mention that Musk envisions the entire system being self-powered by solar panels, and that it somehow stores energy inside the system itself, without the need for batteries?

The Hyperloop is from Tesla founder, Elon Musk. He is set to unveil the plan on August 12—I’ll be interested to see what it is.