(a) Show that, for two large systems in thermal contact, the number Ω(0)(E(0),E1) of Sec. 1.2 can be expressed as a Gaussian in the variable E1. Determine the root-mean-square deviation of E1 from the mean value Eˉ1 in terms of other quantities pertaining to the problem.
(b) Make an explicit evaluation of the root-mean-square deviation of E1 in the special case when the systems A1 and A2 are ideal classical gases.