Slowing down light

By use of a Bose--Einstein condensate, Danish physicist Lene Vestergaard Hau (Harvard University) succeeded in slowing a beam of light to about 17 metres per second, and, in 2001, was able to momentarily stop a beam completely.

About a decade ago, Hau started playing with BECs — for a physicist, that means shooting lasers at them. She found that lasers of the right wavelengths could tune the optical properties of a BEC, giving Hau an almost supernatural command over any other light shined into it.

Her first trick was slowing a pulse of light to a crawl — 25 kmph as it traveled through the BEC. Since then, Hau has completely frozen a pulse and then released it. And recently she shot a pulse into one BEC and stopped it — turning the BEC into a hologram, a sort of matter version of the pulse. Then she transferred that matter waveform into an entirely different BEC nearby — which emitted the original light pulse. That's just freaky. Hey, Einstein may have set that initial speed limit of light, but he only theorized about BECs. "It's not breaking relativity," Hau says. "But I'm sure he would have been rather surprised."

This clip was taken from BBC documentary Absolute Zero.

The Bose-Einstein condensation of matter

In school we all learned that there are 3 states of matter; solid, liquid and gas. It turns out that we have been lied to. Most people will have heard of plasma which is sometimes called the 4th state of matter but there are many more. Have you ever heard of the Bose-Einstein Condensate phase of matter? Prepare yourself for some truly mindblowing stuff.

 More info: Wikipedia - Bose-Einstein condensate

 This clip was taken from a two part BBC series called absolute zero. Part 1 is called "The conquest of cold" and part 2 "The race for absolute zero". PBS has cut down that material to a single episode called absolute zero (1h40, HD) but I would recommend watching the longer BBC version.