The students spent the next 20 minutes waiting anxiously as pumps sucked nearly all the air from the tube. They were the third and final team to get a run in the last stage of Elon Musk's hyperloop competition. The only criterion for winning? Speed.

When many people hear the word hyperloop, they think it's some sort of fixed product that Musk proposed five years ago. Rather, it's more a genre of transportation than a single invention. The basic concept calls for a passenger- or cargo-packed pod inside a nearly airless tube, zooming at high speeds thanks to minimal friction and air resistance. The details—whether and how to make the pod levitate, how to propel it, what shape it should be, and so on—are anyone's guess. Musk laid out some particulars in a 2013, but the people trying to bring this concept to life treat the white paper he wrote that lay out these ideas as a starting point, not gospel.