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What causes light to slow in a Bose-Einstein condensate?
Is it chemical/structural? Does it affect space/time?
This article mentions ..."One laser is shot across the width of the cloud of condensate. This controls the speed of a second pulsed laser beam shot along the length of the cloud. The first laser sets up a "quantum interference" such that the moving light beams of the second laser interfere with each other. When everything is set up just right, the light can be slowed by a factor of 20 million." So it seems the interference pattern created by one beam slows a second later beam of light. Perhaps like a ship passing through the wake of another?
http://www.hno.harvard.edu/gazette/1999/02.18/light.html
Though I had read a few years ago that someone had slowed light to an astounding crawl--on the order of feet or even inches per second--I didn't know (or had forgotten) what a Bose-Einstein condensate was until I researched a bit to answer your question. Interesting.
"In 1999, Danish physicist Lene Vestergaard Hau led a team from Harvard University who succeeded in slowing a beam of light to about 17 metres per second and, in 2001, was able to momentarily stop a beam. She was able to achieve this by using a superfluid." (from Answers.com)
What I find even more interesting than the *slowing* of light is what's described in this passage, from the same Web page:
"Hau and her associates at Harvard University have since successfully transformed light into matter and back into light using Bose-Einstein condensates. Details of the experiment are discussed in an article in the journal Nature, 8 February 2007."
I was also amazed to read, at the article you linked to, of the mind-bendingly-low pressures and temperatures required (and achieved) to produce the condensate... "Vacuums hundreds of trillions of times lower than the pressure of air at Earth's surface, and temperatures almost a billion times colder that that in interstellar space..." Wow!!
Does the lower speed affect space/time? I certainly don't know the answer, but inferring from your reference, I would think not...
"Einstein's theory of relativity places an upper, but not lower, limit on the speed of light....According to relativity theory, an astronaut traveling at close to the speed of light will not get old as fast as those she leaves behind on Earth. But driving at 38 miles an hour [the speed light was slowed to], as everyone knows, will not affect anyone's rate of aging."
What, exactly, causes it to happen? I wish I had time to research this further, but skimming over the pages below, I think they could possibly answer that part of your question. At any rate, your 'ship in the wake of another' comparison sounds plausible. Or, as I see it, maybe like "standing waves" of sound affect the volume and/or pitch (as I understand it). Just a guess. But I'm really stretching, because I've forgotten some of these concepts over time!
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