Friedmann-Lemaître-Robertson-Walker metric
The Friedmann–Lemaître–Robertson–Walker (FLRW) metric is an exact solution of Einstein's field equations of general relativity; it describes a homogeneous, isotropic expanding or contracting universe ...
Friedmann-Lemaître-Robertson-Walker metric - Wikipedia
Friedmann equations
The Friedmann equations are a set of equations in physical cosmology that govern the expansion of space in homogeneous and isotropic models of the universe within the context of general relativity. Th...
Friedmann equations - Wikipedia