The philosophy of physics investigates the logical, conceptual, metaphysical, and epistemological foundations of the physical sciences, especially fundamental physics. It is concerned with general issues such as the subject matters and aims of physics, the nature of physical laws, the direction of time, and issues specific to particular theories such as the measurement problem in quantum mechanics and the status of the second law in thermodynamics. The philosophy of physics is enormously relevant to traditional metaphysics because it addresses the implications of physical theories for fundamental ontology, the natures of time and space, laws, causal relations, counterfactuals, and natural kinds. This encyclopedia includes entries on general, specific, and metaphysical issues in the philosophy of physics, so this entry will serve mainly as a guide to the main problems in philosophy of physics and to direct the reader to more specific articles.

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