Astrophysics seeks to explain observed phenomena in terms of known, and sometimes speculative, physical processes and mechanisms. Insights from astronomy have important implications for the physical sciences in general, and physics in particular. Astronomical objects and processes often represent extreme physical conditions, such as strong gravitational fields, extreme particle energies and temperatures, and velocities close to the speed of light. These objects and processes serve as remote laboratories in which processes or conditions that cannot be replicated on earth can be examined. Astronomy also helps to provide an understanding of the origin and evolution of the universe that is of deep cultural significance.