Light Traveling at 38 Miles an Hour

the-empty-string writes "A Danish physicyst and her team managed to slow down a beam of light to an astonishing speed of only 38 miles per hour. It's on the front page of the New York Times." Update: 02/18 12:20 by H :One of our more scientifically inclined readers sent in a better explanation-click below to read it.

Mike Schiraldi writes "There has been so much misinformation and confusion on /. regarding slowing down the speed of light.. So many comments are along the lines of "Wow, i thought the speed of light was constant. I can get a car with slow headlights and drive faster than the beams!"

You can't let so many people be misinformed. Please let them know:

The speed of light IN A VACUUM is the constant c.

Science has been able to slow light down for centuries by making it travel through a different medium. The speed of light in air is less than c. The speed of light in water or glass or plastic is less than c. This is what makes lenses work. (check your encyclopedia for more information)

The reason this is a breakthrough is simply because they've been able to slow light down to a much lower speed than anyone else has ever been able to do. They have not changed c, the speed of light in a vacuum. The beam of light is only slowed down when it's in the condensate. Once it leaves the condensate and is travelling through air again, it returns to a speed of 186,000 miles per second. This does not contradict any law of physics. "