Let's pretend that you are inside a spherical shell with a uniform density.

假设您在一个密度均匀的球壳内。

The Sun isn't actually of uniform density and photons will miss quite a few protons between every collision.

太阳实际上并不具有均匀的密度，并且光子在每次碰撞之间都会错过相当多的质子。