#Cosmology

Cosmology is the branch of physics that studies the universe itself — its origin, structure, history, and ultimate fate. The story it tells is improbable: a Big Bang 13.8 billion years ago, a brief inflationary expansion, the formation of stars and galaxies, and the discovery that most of the matter and energy in the universe is something we cannot yet directly observe (the dark matter and dark energy that together make up roughly 95% of the total). The posts collected under this tag cover the evidence behind that picture and the questions that remain.