Friday, March 22, 2019
Superfluids and Superconductors :: physics
In 1924, the Indian physicist S. N. Bose developed an alternate law of radiation which modified Plancks laws to embarrass a new variety of particles, namely, the boson. He sent off his hypothesis to Einstein for revision and translation, and Einstein swiftly came up with some additions to the theory. He expanded the laws to incorporate the mass of the boson, and in doing so theorized a distant phenomenon. He predicted that when atoms of a gas came together under cold adequacy temperatures, and belatedlyed down significantly, that they would all assume the exact same quantum state. He knew that this slow quantum gas would endure strange properties, but wasnt able to get frequently further by theorizing. This phenomenon, which came to be known as a Bose-Einstien condensate, was an undreamed of leap in quantum theory, but it wasnt demonstrated until 1995 when Eric A. Cornell, Wolfgang Ketterle and Carl E. Wieman made the prototypic Bose-Einstein condensate with supercooled alk ali gas atoms. Although this development didnt come until late in the twentieth century, many of these strange properties were observed in supercooled He4 by Dr. Pyotr Kapitsa. Helium became the commonplace for observing superfluid phenomenon, and most new superfluid properties are still observed first in Helium 4.Superconductivity, a similar phenomenon, was ascertained in 1911 by Dutch physicist Heike Kamerlingh Onnes. When he cooled some mercury down to liquid helium temperatures, it began to conduct electricity with no resistance at all. People began experimenting with other metals, and found that many tranisition metals exhibit this characteristic of 0 resistance if cooled sufficiently. Superconductors are analagous to superfluids in that the charges within them move somewhat like a superfluid - with no resistance through sections of extremely small cross-sectional area. Physicists soon discovered that oxides of copper and other compounds could reach even higher superconduct ing temperatures. Currently, the highest temperature at wich a material can be superconductive is 138K, and is held by the compound Hg0.8Tl0.2Ba2Ca2Cu3O8.33. Superfluids all have the unique quality that all their atoms are in the same quantum state. This actor they all have the same momentum, and if one moves, they all move. This allows superfluids to move without abrasion through the tiniest of cracks, and superfluid helium will even flow up the sides of a jar and over the top. This apparant defiance of gravity comes from a special grapheme of surface wave present in superfluid helium, which in effect pushes this extremely thin film up the sides of the container.