What is cosmology?

The universe in the large

Cosmology is the study of the universe as a whole: its history, evolution, composition, dynamics. The primary aim of research in cosmology is to understand the large-scale structure of the universe, but cosmology also provides the arena, and the starting point, for the development of all the detailed small-scale structure that arose as the universe expanded away from the Big Bang: galaxies, stars, planets, people. The interface between cosmology and other branches of astronomy, physics, and biology is therefore a rich area of scientific research. Moreover, as astronomers have begun to be able to study the evidence for the Big Bang in detail, cosmology has begun to address very fundamental questions of physics: what are the laws of physics at the very highest possible energies, how did the Big Bang happen, what came before the Big Bang, how did the building blocks of matter (electrons, protons, neutrons) get made? Ultimately, the origin of every system and structure in the natural world, and possibly even the origin of the physical laws that govern the natural world, can be traced back to some aspect of cosmology.