Equation 3.5 is known as the Boltzmann formula and the entropy calculated from
it is sometimes called the statistical entropy. We see that, if W= 1, which corresponds
to one microstate (only one way of achieving a given energy, all molecules in exactly
the same state), then S = 0 because ln 1 = 0. However, if the system can exist in more
than one microstate, then W> 1 and S > 0. If the molecules in the system have access
to a greater number of energy levels, then there may be more ways of achieving a given
total energy, that is, there are more microstates for a given total energy, W is greater,
and the entropy is greater than when fewer states are accessible.