Hello, I am reading this paper about quantum gravity, trying and failing to follow along in the derivation of this, eq (204) p. 72, expression for the scale factor:(adsbygoogle = window.adsbygoogle || []).push({});

[itex]

a(t) = a_1 \left( 1 + \frac 3 2 ( 1 + \omega ) H_1 (t - t_1) \right)^{\frac 2 {3(1+\omega)}}

[/itex]

(I'm not sure what the subscript 1 means, it's not clear from the text)

This we apparently can get from the equation

[itex]

3 H^2 - c^2 \Lambda = \frac{8 \pi G} {c^2} \rho

[/itex]

and

[itex]

\rho (t) = \rho_1 (\frac {a(t)} {a_1} )^{-3(1+\omega)}.

[/itex]

Could anyone help me with this?

/Rettaw

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Deriving a scale factor expression for FLRW model

**Physics Forums | Science Articles, Homework Help, Discussion**