Harvard physicist Lene Hau was able to slow light down to 37 miles an hour

Did you know that in 1999 Harvard physicist Lene Hau was able to slow light down to 37 miles an hour, and was later able to stop light completely.

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. And just this year, she did something even more amazing – she stopped light dead in its tracks.


Light travels at the “speed of light” – 300 million meters (186,000 miles) per second – only in a vacuum. Whenever light travels through a substance, its speed is slowed. For example, in water, light travels at only 225 million meters (140,000 miles) per second.”

Lene Hau (pronounced LEE-nuh HOW) always knew this, but she never expected to break the slow-speed record for light. She grew up in Denmark, and got a Ph.D. at the University of Århus, studying the physics of solids. After she graduated, she received a Carlsberg Foundation fellowship – an award given by the Danish brewery Carlsberg for study abroad. She visited several physics programs around the U.S., and was interested in the Rowland Institute of Science in Boston. “It was a fantastic research place,” she said. Soon after she arrived, she launched a new research project: the search for a new state of matter called the Bose-Einstein Condensate.

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