Any science involved in studying phenomena or laws of the physical world: physics, chemistry, biology, astronomy, and so on.
The physical aspects of a phenomenon or a system, especially those studied scientifically.
Newtonian physics was extended by Einstein to explain the effects of travelling near the speed of light; quantum physics extends it to account for the behaviour of atoms.
The branch of science concerned with the study of the properties and interactions of space, time, matter and energy.