FLRWModell

The FLRW model, named after its developers Alexander Friedmann, Georges Lemaître, Howard P. Robertson, and Arthur Geoffrey Walker, is a mathematical model used in physical cosmology to describe the evolution of the universe. It is based on Einstein's field equations of general relativity and assumes a homogeneous and isotropic universe. The model is characterized by two main parameters: the scale factor, which describes the expansion or contraction of the universe, and the cosmological constant, which represents the energy density of empty space.

The FLRW model predicts that the universe can expand or contract, depending on the value of the cosmological constant and the density of matter in the universe. If the density of matter is greater than a critical value, the universe will eventually stop expanding and begin to contract, leading to a "big crunch." If the density is less than the critical value, the universe will continue to expand indefinitely, leading to a "big freeze." If the density is exactly equal to the critical value, the universe will expand at a constant rate, leading to a "flat" universe.

The FLRW model has been successful in explaining many observed features of the universe, such as the cosmic microwave background radiation and the large-scale structure of the universe. However, it does not account for the observed acceleration of the universe's expansion, which is attributed to dark energy. Despite this limitation, the FLRW model remains a fundamental tool in modern cosmology.