Friedmann Equation. The friedmann equation is the heart of these concepts. However before jumping to the friedmann equation we should construct a basic understanding of cosmology.
First we derive them in the framework of the general relativity keeping the relativistic expressions as a reference for the rest of the report. For now to explore some consequences of the friedmann equation we assume ρ a 3. One version of the einstein equations is the friedmann equation which describes how the expansion rate changes over time and why in a homogeneous and isotropic universe.
They were first derived by alexander friedmann in 1922 from einstein s field equations of gravitation for the friedmann lemaître robertson walker metric and a perfect fluid with a given mass density ρ displaystyle rho and pressure p displaystyle p.
If you want to know where the universe came from and where it s headed all. It explains the evolution of the universe as a function of time for different type of models. The friedmann equation is the heart of these concepts. This is a model that most cosmologists over 25 years ago thought was probably an excellent approximation to reality.
