Cosmic expansion
Cosmic expansion refers to the large-scale increase in distance between gravitationally unbound regions of the universe over time. It is inferred from observational evidence indicating that distant galaxies recede from one another.
Cosmic expansion is discussed in cosmology, astrophysics, and observational astronomy.
Status
Cosmic expansion is supported by redshift measurements and distance observations of extragalactic objects. Its rate and long-term behavior are modeled using cosmological parameters and remain subjects of ongoing study.