Today we will be discussing...

A great thing indeed!!

Physics yata toh no!

Physics in our world- the physics world!!! How very interesting!!

Don't you think so??

Maybe right now you're mumbling... "Oh come on!"

But, hey! You won't be saying that after reading... this...

Physics: Scientists Slow the Speed of Light

A scientific experiment has managed to reduce the speed of light by a factor of 20 million, creating the opportunity for a variety of futuristic advances in everything from computers to night-vision devices. The development was reported in the
February 18, 1999, issue of the journal Nature.
Scientists used a special high-density clump of atoms known as a Bose-Einstein condensate chilled to a tiny fraction of a degree above absolute zero in order to slow a beam of light to just 61 km/h (38 mph). Absolute zero is the lowest temperature theoretically possible, approximately -273.16° C (-459.69° F). The speed of light in a vacuum is 299,792,458 meters per second (about 186,000 miles per second).

The breakthrough was made at the Rowland Institute for Science, a nonprofit research center in Cambridge, Massachusetts. The lead researcher on the project was Lene Vestergaard Hau, head of the Atom Cooling Group at the Rowland Institute and a member of the physics department at Harvard University in Cambridge. The team was assisted by physicist Steve Harris of Stanford University in California.

The “Bose-Einstein condensate” was theorized by Indian physicist Satyendra Nath Bose and German physicist Albert Einstein in the 1920s but was not actually created in the laboratory until 1995. This condensate can be described as the state in which atoms have been cooled to such an extreme they merge into a dense mass that behaves like a single atom. In the Rowland Institute experiment, sodium atoms were slowed and cooled until the atoms locked together in what Harris termed an “optical molasses.” (For more on the Bose-Einstein condensate, see the Encarta Sidebar “Physicists Condense Supercooled Atoms, Forming New State of Matter.”)

The scientists then fired two laser light beams through the condensate. The first beam created a quantum mechanical system combining the atoms in the condensate and the laser light. This system is hugely refractive, so that when the second light beam was shot through at right angles to the first, the second beam was slowed dramatically. Hau said the team's next goal was to use improved laser beam technology to slow the speed of light to a crawl, 1 cm (about 0.4 in) per second.

The scientists cited optical computing as a potential future application of the discovery, in which single photons of light would replace the electronic pulses used in current computers. Because optical computing promises the possibility of much tinier switches that generate less heat, it would revolutionize the speed and size of computing technology. In addition, new types of laser and night-vision devices would need many times less power than currently required. Hau suggested that such developments could be ten years away or less if research is stepped up.

The home Web page of the Rowland Institute for Science provides more information about the center's programs. The Light and Optics page hosted by Arizona State University provides a general discussion of the properties of light.