How You Can Get Temperatures Below Absolute Zero

It used to be that scientists all agreed that it was impossible to achieve temperatures below absolute zero, but now they realise that's not entirely true. This video explains how you can reach temperatures below absolute zero.

The phenomenon is made possible by playing with entropy and energy, to change the way groups of particles behave. But better to watch the video than have me explain. We still not entirely sure what to do with the finding though. [New Scientist]