My book calculates the ratio of probability to find an atom in an excited state vs finding it in the ground state in the sun and gets approx 1/109. Essentially this must mean that the ratio of the multiplicities of the system must also be equal to this, i.e.: [itex]\Omega[/itex]2/[itex]\Omega[/itex]1 = 1/109 How can this be possible? Say you excite the atom. The energy that the surroundings in the sun loses is tiny compared to its total energy. So shouldnt the two multiplicities be approximately the same?