How is it possible for physicists to slow light down to 38 miles/hour?

The speed of light in a vacuum is 299,792 kilometers/sec, but inside a pane of glass it is about 30% slower or 100,000 kilometers/sec. What atomic physicist Dr. Lene Hau at the Rowland Institute for Science in Cambridge, Massachusetts managed to do in 1998 was to prepare a Bose-Einstein condensate by cooling sodium atoms to less than 1 billionth of a degreee above Absolute Zero, and shine a laser beam along the long axis of this cigar-shaped cluster of matter. The index of refraction was so high inside this new state of matter that the speed of light inside it was about 38 miles/hour. INSIDE this condensate, it would have been impossible for information, energy or matter to travel faster than 38 miles/hour...but once the light reentered our air, it resumed its normal break-neck speed. It sounds rather mysterious, but it really isn't. The speed of light in a PARTICULAR medium is the maximum limit, but this speed, as James Clerk Maxwell showed in the 1800's, depends on the square root of the ration of the electric and magnetic permeabilities of a particular medium. These quantities are quite maleable, especially when you create new states of matter at the quantum-level.

By the way, you don't have to consider something as exotic as Bose-Einstein condensates to get the speed of light very slow. If it takes 100,000 years for light to get out of the core of the Sun, a distance of about 700,000 km, the effective speed of light in the sun is 700,000 km/3 trillion seconds or about 2 x 10^-7 km/sec!