Protons - "Fundamental Particles"?

It wasn't before a couple of days back, that I've discovered protons as "Fundamental Particles" by my chemistry school notes. Well, are they fundamental at all?

Well, as of the 21st century, they're not. First proposed by Murray Glenn Mann in the 1960s, quarks have transformed our picture of the very small. Protons and neutrons were no longer elementary, and we had a theoretical picture of quarks within protons and neutrons, alias hadrons. Like any other fermion, quarks are believed to have half integer spins, and hence by Spin-Statistics theorem, they obey the Exclusion Principle.

Fermions are divided to 3 "generations", serialized as I, II, and III. However, quarks of generation II and III are heavy enough to instantaneously decay to their much stable counter-parts, quarks of generation I - up (u) & down (d). The stability of this generation of quarks (& leptons) account for matter being composed of electrons, protons and neutron, which are inturn composed of these quarks (i.e protons and neutrons), or they themselves belong to the generation (i.e electron). A proton is composed of 2 up quarks, and a down quark, while a neutron is all about 2 down quarks and a up quark.

Furthermore, quarks also have "colors", or "color charge". "Color" here is nothing like what we classically interpret it, because quarks are way too smaller than the possible wavelenght of corresponding visible light. As Hawking describes, it's just when physicists these days no longer turn to the greeks for names! All hadrons ought to have "white" color charge, which can be obtained as: red + blue + green or anti-red + anti-blue + anti-green, or red/blue/green + anti-red/blue/green, where anti-red, anti-red, and anti-blue are corresponding anti-properties of red, blue and green. Okay, enough of RGB; all protons and neutrons are composed of a red, green, and blue quarks, and that's about it.

Can quarks exist unconfined in space? They can, under impossibly crunchy extremes (during the quark epoch: see below). Otherwise they're taken care of by asymotic freedom; the further they are to drift apart, stronger the strength of their bind, (which is apparently caused by bosons called "gluons"). There are other approaches to the problem, to include those of quantum gravity. Quarks are believed to be bound by either something like a "string" (which is apparently not related to the string theory), or quantized force field lines. Then came the principle of duality, to claim that "strings" and "field lines" are just 2 different ways of looking at the same thing. Voila! They were unified and further interpreted to form Loop Quantum Gravity, a brand new perception of space at the fundamental level, or the Planck scale.

Infact, the theory of Big Bang lays a deal on quarks. It defines a "quark epoch", when the electroweak symmetry (i.e the symmetry between the weak and electromagnetic forces) was eliminated. The temperature was high enough to not let hadrons form. Quarks existed unconfined in space, until the hadron epoch, when particles like protons and neutrons formed.

Whatever may it be, protons ARE NOT elementary.