Effective number of relativistic degrees of freedom
= Effective number of relativistic degrees of freedom
{title2=$g_{*s}$}
= Effective number of relativistic entropy degrees of freedom
{synonym}
The effective number of relativistic entropy degrees of freedom is defined by
$$
s=\frac{2\pi^2}{45}g_{*s}T^3.
$$
A relativistic bosonic degree of freedom contributes one, while a relativistic fermionic degree of freedom contributes $7/8$ when all species share a temperature.