chemoleo - 2-2-2004 at 14:38
Recently it was in the news that they discovered a new form of matter. Could someone, like a physicist in spe (like I_am_a_Fish 
) explain exactly what it is?
I could attempt to reproduce what was said in the newspaper, but it was very unscientific, and it's probably not worth reproducing it myself.
Anyway, all it said, that there are 5 states so far, gases, liquids, solids, plasma and the Bose-Einstein condensate. The sixth one is made of
fermions (so of whole atomic nuclei?) and could potentially be used for room temperature superconductors... one day.. anyone care to comment?
I am a fish - 2-2-2004 at 15:20
Particles can be divided up into two categories. Bosons have integer spin (e.g. photons, He4 nucleii), while fermions have half integer spins (e.g.
electrons, protons). This distinction is important as any number of bosons can be placed in the same quantum state, while only one fermion can be
placed in a single quantum state (for example, all the electrons in an atom must have different quantum numbers).
At low temperatures, the momenta of particles become very small and so are very precisely defined. By Heisenberg's uncertainty principle, this
leads to a great uncertainty in the positions of the particles. If the temperature is low enough, the wavefunctions of the particles can overlap to
form a so-called condensate. In a bosonic condensate (first produced in 1995), large numbers of particles occupy the same quantum state. However,
fermions can't do this and so a fermionic condensate (which has just been produced) will have very different properties.
See:
http://www.physicsweb.org/article/news/8/1/14
new state of matter
maayan - 15-2-2004 at 00:35
Does anyone think that it is significant that this state was found by the same people who are doing most of the government's work on quantum
computing?
Organikum - 15-2-2004 at 06:52
Isnt "supercritical" also to be regarded as a state of matter?