Stirred, but not shaken
Andy M. linked me to a very interesting article on how scientists at Harvard University are doing very cool things with passing light through Bose-Einstein condensates, like slowing it to a snails pace, or stopping it and starting it somewhere else.
For those of you not familiar with Bose-Einstein condensates, a short lesson: in the 1920s Albert Einstein, building on the work of Satyendra Nath Bose, postulated that at extreme cold, close to absolute zero, a new state of matter would exist. In 1995 this matter was created for the first time, by Eric Cornell and Carl Wieman, a discovery that earned them the Nobel Prize in Physics in 2001. The awesome thing with Bose-Einstein condensates is that they display quantum mechanical properties on a macroscopic scale, leading to all sorts of fun. One of these fun things is that if you are light, a Bose-Einstein condensate behaves like molasses.
The thing that bugs me about the article is the opening statement:
Lene Hau has already shaken scientists’ beliefs about the nature of things. Albert Einstein and just about every other physicist insisted that light travels 186,000 miles a second in free space, and that it can’t be speeded-up or slowed down. But in 1998, Hau, for the first time in history, slowed light to 38 miles an hour, about the speed of rush-hour traffic.
It’s unbelievably misleading. Yes, Hau slowed light to a never-before reached speed (or lack thereof), but not in free space. She did it in a material. And as anyone who has done any science at all already knows, it’s nothing new that light slows in a material. Nothing has been shaken. Every scientists does still insist that light in free space can’t be sped up or slowed down. It’s an utterly irrelevant statement.
Anyway, as interesting as it is, it will be a long time before it has any kind of practical application. The material is incredibly fragile, it has to be cooled to temperatures measured in nanokelvin before it even exists, and we can currently only make a few million atoms at a time under very carefully controlled conditions. Still, it’s fun to think about the applications, as some scientists are proving. As one website points out, it’s as if 400 years ago a giant iceberg washed up in Tahiti – what would a native Tahitian do with an iceberg, or think of ice, if they’d never seen it before? That’s what BEC is to us now, and that’s really kinda cool (pun intended).