Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: chris on 13/07/2012 08:15:48
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What's a Bose-Einstein condensate, why does it form and why is it useful?
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A Bose Einstein condensate is a very interesting state that groups of similar subatomic particles and assemblies with whole integer net spin can achieve at very low energies. All the particles are in the ground state and totally indistinguishable from each other so they (or their wave functions) can be said to exist superimposed within the same volume of space.
It is interesting to note that this is usually created using bosonic atoms at very low temperatures. Atoms of course are formed from protons electrons and neutrons which are fermions (particles with half integer spin that cannot exist in this state) but the fact that all the spins are balanced out allow groups of the whole atom to achieve this state.
When groups of fermions are reduced to the lowest possible energy level they are all slightly different because they cannot have exactly the same energy and some must have higher energy than others this effectively creates a pressure. It is this pressure in electrons and nucleons that prevents white dwarf and neutron stars respectively from collapsing into black holes.
I know of no use for a Bose Einstein condensate and would be interested to hear if there is one.
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Don't the cooper pairs - which are the current leading theory explaining super-conductivity - have remarkable similarities to BECs. Two (half-integer spin) fermions can form a cooper pair and act as a boson - at low temperatures these boson cooper pairs can condense into the same quantum ground state, and it is this action that allows superconductivity. And anything that guides us on the path to future discoveries in superconductivity has got to be good.
I have also read that some BECs have such a ridiculous index of refraction of light that the speed of light within them is less than a walking pace - and almost complete slow down has been approached; what good this might be heaven only knows.
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I would say it's a example of symmetries, and that it takes our knowledge of the universe, and so also what we are ourselves, one small step further :)
And they have so weeiiird properties.
Almost magical, ahem..
(Don't shoot me now:)