Superfluids
"As we shall see, it is generally believed that the phenomenon of superfluidity is directly connected with the fact that the atoms of helium-4 obey Bose statistics, and that the lambda-transition is due to the onset of the peculiar phenomenon called Bose condensation." (Leggett, 1989) This is the phenomenon wherein the bosons (a type of particle) making up a substance merge into the lowest energy level, into a shared quantum state. In general, it refers to the tendancy of bosons to occupy the same state. This state, formed when a gas undergoes Bose-Einstein condensation, is called a "Bose-Einstein condensate." The distinguishing feature of Bose-Einstein condensates is that the many parts that make up the ordered system not only behave as a whole, they become whole. Their identities merge or overlap in such a way that they lose their individuality entirely. A good analogy would be the many voices of a choir, merging to become 'one voice' at certain levels of harmony. The phenomenon of superfluidity was discovered in 1937 by a Russian physicist, Peter Kapitza, and then studied independently in 1938 by John Frank Allen, a British physicist, and his coworkers. I
This superfluid moves without friction, squeezes through impossibly small holes, and it can even flow uphill. This alignment of spins can explain why properties of superfluid helium-3 are different in different orientations. Fermions cannot undergo Bose-Einstein condensation, but the nuclei in helium-3 can 'disguise' itself as bosons by pairing up to form Cooper pairs, which behave as bosons. The nuclei of bosons may pass through each other and can occupy the same quantum state simultaneously therefore behaving as a single entity. (Leggett, 1989)TECHNIQUES FOR STUDYING SUPERFLUIDS Helium is an inert gas, and it is present in ordinary air (about one part in 200 000). , Cambridge Tilley R, Tilley J. Helium-3, having a spin of +1/2 belongs to a different group of particles, called fermions. Superfluidity is found in helium II but it has limited uses. 17K (-271O C or -456 O F, could flow with no difficulty through extremely small holes, which liquid helium at a higher temperature cannot do.
Common topics in this essay:
Helium II,
Prize Physics,
HELIUM Superfluidity,
SUPERFLUIDS Helium,
CONCLUSION Superfluidity,
BOSE-EINSTEIN CONDENSATION,
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Cornell University,
Tilley Tilley,
Allen British,
superfluid helium-3,
liquid helium,
low temperature,
bose-einstein condensation,
superfluidity helium-3,
superfluid helium,
helium ii,
phase transitions,
low temperatures,
fur physik germany,
leggett 1989,
define temperature scales,
zeitschrift fur physik,
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