Physicists explore and identify basic principles and laws governing motion and gravitation, the macroscopic and microscopic behavior of gases, and the structure and behavior of matter, the generation and transfer between energy, and the interaction of matter and energy.
Some physicists use these principles in theoretical areas, such as the nature of time and the origin of the universe; others apply their knowledge of physics to practical areas, such as the development of advanced materials, electronic and optical devices, and medical equipment.