One thing we were raised to know in science class is that absolute zero means absolute zero. That is the absolute coldest that something can possibly get.
That still appears to be true. But not in the sense of lowest-possible-temperature. Just in the sense of coldness. You see, a team at the Ludwig-Maximilians University Munich and the Max Planck Institute of Quantum Optics over in Germany were able to create a temperature below absolute zero: they took some quantum potassium gas, got it down to a couple nanokelvins above absolute zero, and then, in true Doctor Who fashion, reversed the polarity. All of a sudden, they had a gas coming in a few nanokelvins below absolute zero.
What happened? Well, did you ever play SimCity for the SNES? There was a cheat you could exploit that, if you performed a certain set of actions regarding taxes and expenditures, would wrap you around from $0 to $999,999. That appears to be what happened here: the atoms went from the lowest energy rate possible to the highest. That is to say, they went from absolute cold to absolute hot.
And then before you know it, even though Ulrich Schneider, one of the heads of the project, is careful to try and tamp down speculation over potential applications given the limitations they observed, you're seeing perpetual-motion machines and all sorts of sci-fi errata being put on the table all over again.
Because if you can't trust absolutes anymore...