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quote:Originally posted by Solvay_1927If I recall correctly, there are two general types of particles - "bosons" (e.g. photons) and "fermions" (e.g. electrons and protons and quarks - the stuff that all "matter" is made of).You can get as many identical bosons as you like (an infinite number of them, in fact) into the same point in space without them interfering with each other and without their properties being affected. But no two identical fermions can occupy the same position in space (at least, not above absolute zero).So an infinite number of photons (which are bosons) can be concentrated in a single point - they wouldn't be identifiable as a "liquid", it would just be a (very high energy) "point" in space. Only fermions could form anything that could be thought of as a "liquid" (or indeed a "plasma" or whatever).A Bose-Einstein Condensate (ref: the above link) is a way of getting fermions to act like bosons (by getting them close to absolute zero). But I've not heard of any theory or technique that does the opposite - i.e. that could get bosons to act like fermions (and so demonstrate "liquid" or "plasma"-like properties. (Unless that could happen at infinitely high temperatures or something???)Or maybe I don't know what I'm talking about. (Perhaps we'd be better off just waiting for Ian/Soul Surfer to turn up put us all out of our misery. )
quote:All elementary particles are either bosons or fermions. The spin-statistics theorem identifies the structural properties that differentiate fermions and bosons. Fermions have an odd number of energy bearing unit particles of matter in the structure of the particle, and bosons have an even number of energy bearing unit particles of matter in the structure of the particle.Gauge bosons are elementary particles which act as the carriers of the fundamental forces such as the W vector bosons of the weak force, the gluons of the strong force, the photons of the electromagnetic force, and (in theory) the graviton of the gravitational force.Particles composed of a number of other particles (such as protons or nuclei) can be either fermions or bosons, depending on their total spin. Hence, many nuclei are in fact bosons. So even though the main three massive subatomic particles i.e. the proton, neutron, and electron are all fermions, some atoms and their isotopes are bosons due to the fact that spin can either be spin-up or spin-down which cancels for each pair of even numbered unit particle of matter structures designated as bosons, but there is a net energy rotation or net "spin" for fermions which are odd numbered unit particle of matter structures.An example of how different atoms are either fermions or bosons: Both the neutron and the proton have 9 energy units, so that alone, each is a fermion having a total of an odd number of unit particles. However, in helium-4 there are two protons and two neutrons, therefore, the nucleus is made up of four particles of 9 energy units each making 36 energy units total making the helium-4 nucleus a boson. Adding the two electrons around a helium-4 nucleus each with spin-up and spin-down making a pair of energy units still makes an even number of energy units in the entire atom making a total of 38. Therefore, the entire helium-4 atom is a boson even though it is made up of individual fermions i.e. the proton, neutron and electron. On the other hand, an isotope of helium, the helium-3 atom is a fermion because it contains two protons and one neutron of 9 energy units each making 27 in total in the nucleus and adding the two electrons still makes an odd number 29.