" (2) prescriptive, i. e . , the model prescribes the original. If the deviation from model to original cannot be tolerated then the original has to be changed. Design models are in a prescriptive reference mode to their originals, i. e. , the implementation. America Next Top Super Model (3) idealizing, i. e. "

" Therefore, it would be possible to "overtake" a neutrino, choosing a reference frame in which its direction of motion is reversed without affecting its spin (making it right-handed). Since then, physicists have revised the Standard Model to allow neutrinos to have mass, which make up additional free parameters beyond the initial 19. A further extension of the Standard Model can be found in the theory of supersymmetry, which proposes a massive supersymmetric "partner" for every particle in the conventional Standard Model. Supersymmetric particles have been suggested as a candidate for explaining dark matter. Although supersymmetric particles have not been observed experimentally to date, the theory is one of the most popular avenues of research in theoretical particle physics. References Textbooks Griffiths, David J. (1987) Introduction to Elementary Particles, Wiley, John & Sons, Inc. Sign Up For America Next Top Model ISBN 0471603864 Journal Articles Y. Hayato et al. "