Editing Galaxy formation and evolution (section)

{{short description|Subfield of cosmology}}
{{Use dmy dates|date=March 2019}}
{{Physical cosmology|expanded=comp/struct}}

In [[cosmology]], the study of '''galaxy formation and evolution''' is concerned with the processes that formed a [[Homogeneity and heterogeneity|heterogeneous]] universe from a [[Big Bang|homogeneous beginning]], the formation of the first [[galaxies]], the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies. Galaxy formation is hypothesized to occur from [[structure formation]] theories, as a result of tiny [[quantum fluctuation]]s in the aftermath of the [[Big Bang]]. The simplest model in general agreement with observed phenomena is the [[Lambda-CDM model]]—that is, clustering and merging allows galaxies to accumulate mass, determining both their shape and structure. Hydrodynamics simulation, which simulates both [[baryon]]s and [[dark matter]], is widely used to study galaxy formation and evolution.