" These parameters cannot be independently calculated. 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. Utah Belt Model Railroad 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. "

" Black paint was also cheaper and more durable. Henry Ford is reputed to have made the statement "Any customer can have a car painted any color that he wants so long as it is black. " Model Ts in different colors were produced from 1908 to 1914, and then again from 1926 to 1927. By 1914, the assembly process for the Model T had been so streamlined it took only 93 minutes to assemble a car. That year Ford produced more cars than all other automakers combined. The Model T was a great commercial success, and for years in the late 1910s and early 1920s it was estimated that more than half of all motorcars in existence in the world were Model T Fords. In fact, it was so successful that Ford did not purchase any advertising between 1917 and 1923; in total, more than 15 million Model Ts were manufactured, more than any other model of automobile for almost a century. Model Railroad General Store This record has now been surpassed by the Volkswagen Beetle, and the Toyota Corolla and Ford F-Series nameplates have both sold more. The record is currently held by the Volkswagen Golf which sold over 21,000,000 units and is still in production today. "