Physical cosmology, as a branch of astronomy, is the study of the largest-scale structures and dynamics of the universe and is concerned with fundamental questions about its formation and evolution. For most of human history, it was a branch of metaphysics and religion. Cosmology as a science originated with the Copernican principle, which implies that celestial bodies obey identical physical laws to those on Earth, and Newtonian mechanics, which first allowed us to understand those laws.

La cosmologie est la branche de l'astrophysique qui étudie l'Univers en tant que système physique.

Kosmologie is de wetenschap die de globale structuur en de evolutie van het heelal bestudeert.