" The Standard Model of particle physics is a theory which describes the strong, weak, and electromagnetic fundamental forces, as well as the fundamental particles that make up all matter. Developed between 1970 and 1973, it is a quantum field theory, and consistent with both quantum mechanics and special relativity . To date, almost all experimental tests of the three forces described by the Standard Model have agreed with its predictions. However, the Standard Model is not a complete theory of fundamental interactions, primarily because it does not describe gravity. The Standard Model The Standard Model contains both fermionic and bosonic fundamental particles. Fermions are particles which possess half-integer spin and obey the Pauli exclusion principle, which states that no fermions can share the same quantum state. Bosons possess integer spin and do not obey the Pauli exclusion principle. America Ashley Model Next Top Informally speaking, fermions are particles of matter and bosons are particles that transmit forces. For a detailed description of the differences between fermions and bosons, see the article on identical particles. "

" S. F. Novaes, Standard Model: An Introduction, hep-ph:0001283 I. 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. America Next Top Model And Sarah 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. "