
Physics used to be philosophy.
For centuries, natural philosophy covered physics, chemistry, and biology. Newton even titled his masterwork Philosophiæ Naturalis Principia Mathematica—"Mathematical Principles of Natural Philosophy."Philosophy: When Science Was 'Natural Philosophy'

Then the split.
As fields matured, they broke off from philosophy. The term gained a narrower meaning focused on metaphysics, epistemology, and ethics.Philosophy: When Science Was 'Natural Philosophy'