Classical unified field theories to isospin rather than electromagnetism; this is related to a discrete (or ""internal"") symmetry known to Einstein as "displacement field duality". Einstein became increasingly isolated in his research on a generalized theory of gravitation, and most physicists consider his attempts ultimately unsuccessful. In particular, his pursuit of a unification of the fundamental forces ignored developments in quantum physics (and vice versa), most notably the discovery of the strong nuclear force and weak nuclear force. Inspired by Einstein's approach to a unified field theory and Eddington's idea of the affine connection as the sole basis for differential geometric structure for space-time,
Pasadena Unified School District 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 members serve four-year terms. Duties of the board include budgeting, approving expenditures, establishing policy, making employment decisions, approving textbooks