US and Australian scientists tested out a new experimental jet engine over the Aussie outback this week, and it broke Mach 10. That's 10 times the speed of sound, or 6,835mph, to the laymen out there.
It's a scramjet, which means it needs to be propelled up to high speed with a rocket before the engine can take over, in this case an air-breathing supersonic combustion engine. Jets of this speed definitely won't be accepting passengers anytime soon, but if and when they do you can expect to get from New York to Tokyo in a little over an hour. Holy crap.