Bose

A Bose–Einstein condensate is a phase of matter formed by bosons cooled to temperatures very near to absolute zero (0 kelvins or -273.15 degrees Celsius). more...

Home
Amplifiers
Audio Accessories & Cables
Cable TV
DVD Players & Recorders
Digital Video Recorders, PVR
Gadgets & Other Electronics
Home Audio
Home Theater Projectors
Home Theater in a Box
Aiwa
Bose
JBL
Kenwood
Other Brands
Panasonic
Pioneer
RCA
Sony
Yamaha
Radios: CB, Ham & Shortwave
Satellite Radio
Satellite TV
Telephones & Pagers
Televisions
VCRs
Vintage Electronics

Under such supercooled conditions, a large fraction of the atoms collapse into the lowest quantum state, at which point quantum effects become apparent on a macroscopic scale.

This state of matter was first predicted as a consequence of quantum mechanics by Albert Einstein, building upon the work of Satyendra Nath Bose in 1925. Seventy years later, the first such condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of Colorado at Boulder NIST-JILA lab, using a gas of rubidium atoms cooled to 170 nanokelvin (nK). Cornell and Wieman and Wolfgang Ketterle at MIT were awarded the 2001 Nobel Prize in Physics in Stockholm, Sweden.

Velocity-distribution data graph

In the image accompanying this article, we see the velocity-distribution data confirming the discovery of the Bose–Einstein condensate out of a gas of rubidium atoms. The false colors indicate the number of atoms at each velocity, with red being the fewest and white being the most. The areas appearing white and light blue are at the lowest velocities. Left: just before the appearance of the Bose–Einstein condensate. Center: just after the appearance of the condensate. Right: after further evaporation, leaving a sample of nearly pure condensate. The peak is not infinitely narrow because of the Heisenberg uncertainty principle: since the atoms are trapped in a particular region of space, their velocity distribution necessarily possesses a certain minimum width. As an interesting aside, this famous graph served as the cover-design for 1999 textbook Thermal Physics by Ralph Baierlein.

Introduction

Condensates are extremely low temperature fluids with properties that are currently not completely understood, such as spontaneously flowing out of their container. The effect is the consequence of quantum mechanics, which states that systems can only acquire energy in discrete steps. If a system is at such a low temperature that it is in the lowest energy state, it is no longer possible for it to reduce its energy, not even by friction. Without friction, the fluid will easily overcome gravity because of adhesion between the fluid and the container wall, and it will take up the most favorable position, all around the container.

Theory

The slowing of atoms by use of cooling apparatuses produces a singular quantum state known as a Bose condensate or Bose–Einstein condensate. This phenomenon was predicted in 1925 by Albert Einstein, by generalizing Satyendra Nath Bose's work on the statistical mechanics of (massless) photons to (massive) atoms (The Einstein manuscript, believed to be lost, was found in a library at Leiden University in 2005). The result of the efforts of Bose and Einstein is the concept of a Bose gas, governed by the Bose-Einstein statistics, which describes the statistical distribution of identical particles with integer spin, now known as bosons. Bosonic particles, which include the photon as well as atoms such as helium-4, are allowed to share quantum states with each other. Einstein speculated that cooling bosonic atoms to a very low temperature would cause them to fall (or "condense") into the lowest accessible quantum state, resulting in a new form of matter.

Read more at Wikipedia.org