Can anyone explain?

[firemeboy]

I heard that in 1999 they slowed down a light wave? And then stopped it? Can anybody shed light on that? In layman terms?

[groza528]

I don't know about stopping, but I thought I once heard that they had slowed a beam of light to 35 mph. They did that by shining it through a bozyne liquid, which is a liquid that is very near to absolute zero.

[Planky]

Zero what exactly?

[firemeboy]

http://news.bbc.co.uk/1/hi/sci/tech/1124540.stm

[Bicho the Inhaler]

I'm not sure of the technical details, but it didn't violate relativity, and it was overhyped. Actually, it was the information about the light wave that was made stationary and then converted into another light wave. Practically, this is more or less the same as stopping the light wave, but no photon actually stood still.

http://www.msnbc.com/news/242698.asp?cp1=1
Here's a news story from 2001.

quote:

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In each experiment, one laser beam excites the atoms in such a way that they can’t absorb light in a traditional sense, a process called electromagnetically induced transparency. Then another laser emits a pulse of light toward the chamber. When the pulse enters the chamber, the photons and the excited atoms are coupled into quantum systems called polaritons. During this coupling, the properties of the photons are transferred to the atoms, changing or “flipping” their magnetic spin. In a sense, the atoms weigh down the photons, and that drags down the speed of the pulse.
When the pulse is fully within the haze of excited atoms, the intensity of the first laser beam is reduced to zero.
“As we decelerate, the pulse has less and less photons, and at the same time there are more and more excited spins. So when we make the light go infinitely slow ... there are no photons remaining, all of the information is in the spins,” Lukin said.
He stressed that the photons are not absorbed, as they would be under normal conditions. “The photon disappears, but when one photon disappears, one spin flips,” he said.
Hau’s team said the pulse was “frozen” — essentially stored as a quantum pattern imprinted upon the atoms.
In each experiment, the information about the light pulse can be stored for about a thousandth of a second before it starts to decay. When the control laser beam is turned back on, photons are once again introduced into the system. The light pulse starts speeding up again, reaching its original velocity by the time it leaves the chamber.

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