Force A Grand Unified Theory that allows for the combination of the electroweak interaction with the strong force is held out as a possibility with candidate theories such as supersymmetry proposed to accommodate some of the outstanding unsolved problems in physics. Physicists are still attempting to develop self-consistent unification models that would combine all four fundamental interactions into a theory of everything. Einstein tried and failed at this endeavor, but currently the most popular approach to answering this question is string theory. What we now call gravity was not identified as a universal force until the work of Isaac Newton. Before
Pasadena Unified School District in eighth grade. Curricular focus is also placed on History, Social Studies, Science, Art and Music, and Physical Education. Pasadena Unified School District The Pasadena Unified School District is a unified school district that is responsible for the schools of Pasadena, California. , it has four high schools, five middle schools, three K–8 schools and 15 K–5 elementary schools. The number of elementary schools was reduced from 18 at the end of the 2010–11 school year. The district also serves the city of Sierra Madre and the unincorporated community of Altadena. PUSD is run by a board of education, whose