From the statistical point of view, "β" is a numerical quantity relating two macroscopic systems in equilibrium. The exact formulation is as follows. Consider two systems, 1 and 2, in thermal contact, with respective energies "E"1 and "E"2. We assume "E"1 + "E"2 = some constant "E". The number of microstates of each system will be denoted by Ω1 and Ω2. Under our assumptions Ω"i" depends only on "Ei". We also assume that any microstate of system 1 consistent with "E1" can coexist with any microstate of system 2 consistent with "E2". Thus, the number of microstates for the combined system is