From the paper, https://arxiv.org/abs/astro-ph/0305015, on page 3,(adsbygoogle = window.adsbygoogle || []).push({});

How did the author arrived with equation (10)? By using the radiation density and (8) defined in the previous paragraph,

## ρ_r = \frac{3}{4}Ts ~## (radiation density) I think the author got it wrong (## ρ_r = \frac{4}{3}Ts ~##)

## T\dot s + 3HTs = Γ \dot φ ^2~## (8)

We have, ##~T \dot s = \frac{4}{3} \dot ρ_r ~## and ##~ \frac{4}{3} \dot ρ_r + 4Hρ_r = Γ \dot φ ^2~##

But why is that in the paper it is written as ##~ \dot ρ_r + 4Hρ_r = Γ \dot φ ^2~##?

Also, how did the author get the radiation density ## ρ_r = \frac{3}{4}Ts ~## by saying that we set ##~δm_T = 0~## in (2)?

**Physics Forums - The Fusion of Science and Community**

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

# I Entropy production equation

Tags:

Have something to add?

Draft saved
Draft deleted

Loading...

Similar Threads - Entropy production equation | Date |
---|---|

I Heat death of the universe and the 3rd law of thermodynamics | Feb 28, 2018 |

A Entropy and derivations - is my logic faulty? | Dec 27, 2017 |

I Entropy of the last scattering surface and today's universe? | Dec 12, 2017 |

I Does entropy change on horizons | Nov 11, 2017 |

Cosmic strings account for primordial SMBH production? | May 8, 2015 |

**Physics Forums - The Fusion of Science and Community**