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..
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Probably the most famous equation of them all, E=mc2 results from Einstein's theory of special relativity and expresses the fact that mass and energy are the same physical entity and can be changed into each other.
It's simplicity is its power, as it unites two fundamental physical qualities of mass and energy..
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SOLUTIONS TO THE FRIEDMANN EQUATION The Friedmann equation is so named because Friedmann was the first to appreciate, in 1922, that Einstein's equations admitted cosmological solutions containing matter only (although it was Lemaître who in 1927 both obtained the solution and appreciated that it led to a linear .
Probably the most famous equation of them all, E=mc2 results from Einstein's theory of special relativity and expresses the fact that mass and energy are the same physical entity and can be changed into each other.
It's simplicity is its power, as it unites two fundamental physical qualities of mass and energy..
The Friedmann equations start with the simplifying assumption that the universe is spatially homogeneous and isotropic, that is
There are two independent Friedmann equations for modelling a homogeneous, isotropic universe
The density parameter Ω is defined as the ratio of the actual (or observed) density ρ to the critical density ρc of the Friedmann universe
The Friedmann equations can be solved exactly in presence of a perfect fluid with equation of state
Set where a0 and H0 are separately the scale factor and the Hubble parameter today
