" 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. 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. In the Standard Model, the theory of the electroweak interaction (which describes the weak and electromagnetic interactions) is combined with the theory of quantum chromodynamics. Model Trains New Jersey All of these theories are gauge theories, meaning that they model the forces between fermions by coupling them to bosons which mediate (or "carry") the forces. The Lagrangian of each set of mediating bosons is invariant under a transformation called a gauge transformation, so these mediating bosons are referred to as gauge bosons. "

" The original of a model may itself be physical or conceptual. It may be so, independently of the consistency of the model. The model in the arts for example can be understood as an individual that functions as a proxy for certain aspects of a concept such as man, men, woman, child, etc. or as one of these under particular conditions. The original temporally or causally may be a predecessor of the original or a successor of it depending on the case at hand. Often it will be such that historically there can be found an iteration of sequences of model constitution and original constitution. One should not miss out the point that the original as well must be constituted in some way so it becomes accessible to the modeling individual I. Model Train Software IV. The term model is used in many communities with quite different traditions, commonly perceived problems, and purposes. "