In 2001, what did Professor Lene Hau do that Einstein theorized was impossible?

In 1999, after years of practice, Lene Hau learned how to bicycle at the speed of light. She's not a racer; she's a physicist at Harvard University. She didn't achieve this amazing feat by cycling faster; instead, she slowed light down - to an incredible 60 kilometers (37 miles) an hour.

It was by shining precisely tuned lasers on such a condensate, or cloud, of ultra-cold sodium atoms that Dr. Hau and her team reduced the speed of a light beam to a pace slower than her bicycle.

And in 2001, she did something even more amazing - she stopped light dead in its tracks.

By converting light into matter and then back again, physicists have for the first time stopped a light pulse and then restarted it a small distance away. This "quantum mechanical magic trick" provides unprecedented control over light and could have applications in fiber-optic communication and quantum information processing.