Hi, I am currently a student, still grasping some basic concepts of quantum mechanics. I've been reading some books, and the model on quarks intrigue me. There's something I'll like to clarify though. Mass Up Quark - 1.5 to 3.3 MeV/c2 Down Quark - 3.5 to 6.0 MeV/c2 Electron - 0.511 MeV/c2 Electron radius - 2.8179 x 10^-15 (classical radius) Quark radius - unknown Proton radius - 1.0 x 10^-15 (3 times smaller than an electron) Hence, quark radius must be smaller than an electron's radius. ----------------------- So electrons have a charge that is 3 times stronger than a down quark, have a radius that is at least 6 times bigger than a down quark, yet they weigh about 6 to 12 times less than a down quark. 1) Am I right in saying that? Or did I get some values wrong? Because it seems quite absurd to me the way an electron's mass, size and charge compare to a down quark. 2) Also, why are there differing masses of each quark (e.g. 1.5 to 3.3 MeV/c2) whereas electrons have a fixed known mass value of 0.511 MeV/c2? Is this due to experimentation error due to the difficulty of measuring the mass of a quark? Thanks.