The Very Weird Science of Dr. Hau.

This is astonishing stuff:

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.

Two years later, she brought light to a complete halt in a cloud of
ultracold atoms. Next, she restarted the stalled light without changing
any of its characteristics, and sent it on its way. . . .

Now Mallinckrodt Professor of Physics and of Applied Physics, Hau has
done it again. She and her team made a light pulse disappear from one
cold cloud then retrieved it from another cloud nearby. In the process,
light was converted into matter then back into light. For the first
time in history, this gives science a way to control light with matter
and vice versa. — Harvard Press release/Staff photo Justin Ide/Harvard News Office

Watch the video — it’s mind-boggling.
Video: Light and matter (2007) (1:52)