User:Kimhoon1865



d_p ({t_ls}) = R({t_0})\int_{t_ls}^{t_0} \frac{dt}{R(t)} $$



p + e^- -> H+\gamma $$


 * $$\frac{1}{2}$$ $$\frac{2}{3}$$

$$ R \propto t^{2/3} $$

$$ R \propto t^{1/2} $$



t_{rec} = t_0 (\frac{R}{R_0}) = t_0 (\frac{T_0}{T_rec})^{3/2} \approx 1.4 \times 10^{10} years \times (\frac{2.37K}{3500K})^{3/2} \approx 300,000 years $$