" Models are usually man-constituted. That justifies talking about their purpose prior to talking about their consistency . Models are used as substitutes for originals because properties of the latter are of interest and the originals are not going to be investigated themselves. There may be a number of reasons for that such as taboos preventing from studying the original itself, or inability, the involved cost in terms of resources or moral damage being intolerable, or similar. For an investigator I it makes only sense to consider an entity M as a substitute of an entity O, if I can (1) establish an analogy, similarity, or similar relation between M and O that permits the substitution of O by M with respect to purpose and means, time-horizon etc. , and (2) I can actually investigate M in the required way. That implies firstly that M does not have the properties of O that prevent I from investigating O. World Model Airplane Also other properties of O may not be properties of M. In that sense a model is more abstract than its original. "

"6 MeV Muon neutrino νμ 0 2 +1/2 -1/2 1 < 0. 5 MeV Anti-Muon μc 1 1 0 1 1 105. 6 MeV Muon antineutrino 0 1 0 0 1 < 0. 5 MeV Charm quark c +2/3 2 +1/2 +1/6 3 ~1. 5 GeV Strange quark s -1/3 2 -1/2 +1/6 3 ~100 MeV Anti-charm antiquark cc -2/3 1 0 -2/3 ~1. 5 GeV Anti-strange antiquark sc +1/3 1 0 +1/3 ~100 MeV Generation 3 Tau τ -1 2 -1/2 -1/2 1 1. 784 GeV Tau neutrino ντ 0 2 +1/2 -1/2 1 < 70 MeV Anti-Tau τc 1 1 0 1 1 1. Piper Cub Model Airplane784 GeV Tau antineutrino 0 1 0 0 1 < 70 MeV Top quark t +2/3 2 +1/2 +1/6 3 173 GeV Bottom quark b -1/3 2 -1/2 +1/6 3 ~4. 7 GeV Anti-top antiquark tc -2/3 1 0 -2/3 173 GeV Anti-bottom antiquark bc +1/3 1 0 +1/3 ~4. "