In philosophy, the philosophy of physics studies the fundamental philosophical questions underlying modern physics, the study of matter and energy and how they interact. The philosophy of physics begins by reflecting on the basic metaphysical and epistemological questions posed by physics: causality, determinism, and the nature of physical law. It then turns to questions raised by important topics in contemporary physics:
Centuries ago, the study of causality, and of the fundamental nature of space, time, matter, and the universe were part of metaphysics. Today the philosophy of physics is essentially a part of the philosophy of science. Physicists utilize the scientific method to delineate the universals and constants governing physical phenomena, and the philosophy of physics reflects on the results of this empirical research.