Editing Cosmological principle (section)

{{Short description|Theory that the universe is the same in all directions}}
{{cosmology}}
{{unsolved|physics|Is the universe homogeneous and isotropic at large enough scales, as claimed by the cosmological principle and assumed by all models that use the [[Friedmann–Lemaître–Robertson–Walker metric]], including the current version of the [[Lambda-CDM model|ΛCDM model]], or is the universe [[inhomogeneous cosmology|inhomogeneous]] or anisotropic?<ref name="Snowmass21"/><ref name="Billings"/><ref name="Migkas et al"/>}}

In modern [[physical cosmology]], the '''cosmological principle''' is the notion that the spatial distribution of matter in the universe is uniformly [[Isotropy|isotropic]] and [[homogeneity (physics)|homogeneous]] when viewed on a large enough scale, since the forces are expected to act equally throughout the universe on a large scale, and should, therefore, produce no observable inequalities in the large-scale structuring over the course of evolution of the matter field that was initially laid down by the [[Big Bang]].