What Are Negative Temperatures and How Do They Defy Absolute Zero?

[Bobbywhy]

Absolute zero is often thought to be the coldest temperature possible. But now researchers show they can achieve even lower temperatures for a strange realm of "negative temperatures."
http://www.livescience.com/25959-atoms-colder-than-absolute-zero.html

 

[Whovian]

Perpetual heat source and a way to prevent heat death! :D Or, at least, I hope. Probably not really.

 

[Naty1]

Sounds like 'cold fusion' hopes...I'll wait for some experimental verification by others.

 

[D H]

This is the third thread on this topic today.

There's an ongoing discussion on negative temperatures in this thread: [thread]662268[/thread].

I'm closing this thread since there's no reason to have three active threads on the same subject.