means The science of how matter, energy, space, and time behave — from falling apples to colliding galaxies — described through mathematical laws.

from From the Greek 'physis' meaning 'nature,' which gave 'physika' — literally 'things relating to nature.' Aristotle wrote a treatise by that name, and tellingly, his work on first principles came right after it, earning the title 'metaphysics' — literally 'after the physics.' The word reached English through Latin 'physica,' first describing the study of the natural world broadly, before narrowing to the science we know.