10. Models¶

10.1. Homogeneous and Isotropic Neutrino Gas¶

\(\vec P_\omega\) can be time-independent.

Regarding the discussion in Pictures, we know immediately that \(\vec H\) is aligned or anti-aligned with \(\vec P_\omega\) since

\[\vec H \times \vec P_\omega = 0,\]

as \(\vec P_\omega\) is time-independent.

Anyway the equation we need to solve is then

\[\vec a\]

Without solving the equation, we know that

What is special in this model?

To be added.