Light, which normally travels the 240,000 miles from the Moon to Earth in less than two seconds, has been slowed to the speed of a minivan in rush-hour traffic — 38 miles an hour.
An entirely new state of matter, first observed in 1995, has made this possible. When atoms become packed super-closely together at super-low temperatures and super-high vacuum, they lose their identity as individual particles and act like a single super- atom with characteristics similar to a laser.
Such an exotic medium can be engineered to slow a light beam 20 million-fold from 186,282 miles a second to a pokey 38 miles an hour.
“In this odd state of matter, light takes on a more human dimension; you can almost touch it,” says Lene Hau, a Harvard University physicist.
In the future, slowing light could have a number of practical consequences, including the potential to send data, sound, and pictures in less space and with less power. Also, the results obtained by Hau’s experiment might be used to create new types of laser projection systems and night vision cameras with power requirements a million times less than what is presently possible.
It took Hau and three colleagues several years to make a container of the new matter. Then followed a series of 27-hour-long trial runs to get all the parts and parameters working together.
“So many things have to go right,” Hau comments. “But the results finally exceeded our expectations. It’s fascinating to see a beam of light almost come to a standstill.”
here & here (video)