On 12/12/16 3:02 PM, wrote:
So, you're saying Rho_E_today * (1 + 1)^4 = 16 Rho_E_today

is equal to the cbr energy density at redshift z = 1.

So, the energy density today is 1/16 th of the energy density back then.



[[Mod. note -- That's correct. -- jt]]

So, I found a value for CBR energy density today on Wiki at 4.005E-14
J/m^3.
calculation indicates a small difference
given CMR present temperature 2.72548 K

Stefan_constant*2.72548^4)*4/c = 4.17E-14 J/m^3

[[Mod. note -- These small differences are likely just different
rounding of the "same" values. -- jt]]

Using multiplier of (1 + z)^4, I get the following values for
lookback times in 1 Gyr increments. z values came from Ned Wright's
calculator using default settings.

I'm pretty sure I did the math right, but, do the values for CBR energy
density sound about right?

z J/m^3
0 4.005E-14
0.075 5.34855E-14
0.15885 7.2229E-14
0.2534 9.88465E-14
0.3616 1.37658E-13
0.4873 1.95973E-13
0.6363 2.87114E-13
0.8178 4.37307E-13
1.0462 7.02093E-13
1.3474 1.21605E-12
1.7715 2.36299E-12
2.434 5.56934E-12
3.677 1.91634E-11
7.368 1.96376E-10