Laser Cooling, WTF?

Question

I hear you can use lasers to cool stuff, how is this possible? Don't lasers burn stuff?

Answer 1

Well, most lasers burn stuff... What I'm gonna tell you is greatly simplified.

With laser cooling, at least 6 lasers are arranged in a way such that 2 beams are directly opposing each other. If a bunch of atoms (for this is what the laser cools) are caught between the lasers, they will soon lose their energy since the lasers keep them form moving too much.

Since heat, basically, is the average amount of motion of all the atoms in a collection, the material in the region is cooled, significantly that there is a 5th state of matter induced (the Bose-Einstein condensates), with properties very different from solid, liquid, gaseous, and plasma forms.

Answer 2

That is a quite complex technique used to cool atoms near absolute zero temperatures. A good simplifying introduction to the subject can be found at http://www.colorado.edu/physics/2000/bec/lascool1.html