alternative cosmologies

The phase alternative cosmologies (non-standard cosmologies) are used for cosmological models that differ from the standard cosmology (aka the concordance model), i.e., that differ from the current widely-accepted cosmological model, the Lambda-CDM model. Before Hubble expansion was noticed and established as fact, it was generally assumed the universe merely remained through the ages much as viewed and this idea continued to be developed even after the widespread acceptance of the Hubble expansion, this non-expanding model eventually termed the steady state model, which could be called a past standard cosmology which eventually became an alternative. When the cosmic microwave background (CMB) was detected, the steady state model lost much of its acceptance, and a model based on the Big Bang became accepted as the standard cosmology. This standard has since undergone modification, incorporating further theories such as inflation, dark energy, and refined ideas about dark matter, as well as to match more recent observation, resulting in the current standard cosmology, Lambda-CDM. Some recent cosmology ideas do not challenge Lambda-CDM but offer deeper explanation, but often these theories lack practical means of testing their validity. Others merely tweak Lambda-CDM, e.g., characterizing dark energy as other than equivalent to a cosmological constant (Λ). Also, recent proposed (non-cosmological) physics theories often have cosmological implications, such as refinements of the standard model of particle physics, or new theories of gravity, either adjustments or alternatives to general relativity. The latter have been motivated to explain the phenomenon that motivates the concepts of dark matter and dark energy, such as DGP gravity and MOND.