" The model does not describe the gravitational interaction. Since the completion of the Standard Model, many efforts have been made to address these problems . One attempt to address the first defect is known as grand unification. The so-called grand unified theories (GUTs) hypothesized that the SU(3), SU(2), and U(1) groups are actually subgroups of a single large symmetry group. At high energies (far beyond the reach of current experiments), the symmetry of the unifying group is preserved; at low energies, it reduces to SU(3)×SU(2)×U(1) by a process known as spontaneous symmetry breaking. The first theory of this kind was proposed in 1974 by Georgi and Glashow, using SU(5) as the unifying group. A distinguishing characteristic of these GUTs is that, unlike the Standard model, they predict the existence of proton decay. Ashley Car In Model In 1999, the Super-Kamiokande neutrino observatory reported that it had not detected proton decay, establishing a lower limit on the proton half-life of 6. 7× 1032 years. "

" A distinguishing characteristic of these GUTs is that, unlike the Standard model, they predict the existence of proton decay. In 1999, the Super-Kamiokande neutrino observatory reported that it had not detected proton decay, establishing a lower limit on the proton half-life of 6. 7× 1032 years. This and other experiments have falsified numerous GUTs, including SU(5). Another effort to address the first defect has been to develop Preon models which attempt to set forth a substructure of more fundamental particles than those set forth in the Standard Model. In addition, there are cosmological reasons why the standard model is believed to be incomplete. Within it, matter and antimatter are symmetric. Bmw Car Model While the preponderance of matter in the universe can be explained by saying that the universe just started out this way, this explanation strikes most physicists as inelegant. Furthermore, the Standard Model provides no mechanism to generate the cosmic inflation that is believed to have occurred at the beginning of the universe, a consequence of its omission of gravity. "