This is how I do it and I got a huge number for redshift, please let me know if I am doing anything wrong.
TODAY:
rho_matter = rho_critical = 3/8pi * H^2/G = 1e-14 [kg/m^3]
rho_rad = alpha T^4 = 7.56e-16 * 2.74^4 = 4.26e-14 [J/m^3]
Do a unit conversion
rho_rad = 4.26e-14 / c^2 = 4.74e-31...
Thanks Marcus you're smart. Sorry I didn't know there is a homework forum, I searched up the thread on google and thought this would be the right place to ask. I will keep that in mind and post in the correct forum next time.
One question I want to know though, isn't rho_matter/rho_rad =...
I have a homework question I am not sure how to approach:
We are told that
1) CMB provides about 10^9 photons/baryons.
2) For matter dominated era, assume flat university with H_o = 73km/s/Mpc
3) Stefan-Boltzman law for energy density: ρ_rad = αT^4 where α = 7.56x10^-15 ergs / cm^3 K^4...