This quantity can take negative values at small frequencies or at large chemical potential during population inversion. (10[2])Chemical potential, volume, (10[1])and this quantity are the thermodynamic variables for the grand canonical ensemble. (-5[2])One over this quantity times Boltzmann’s (10[1])constant (10[2])equals (10[2])thermodynamic (-5[1])beta. (10[2])This quantity (10[2])is defined using the transitivity (-5[1])of equilibrium in the zeroth law of thermodynamics. (10[3])At constant values of this quantity, Boyle’s law (10[1])states (10[1])that volume (10[1])and (10[1])pressure (10[5])are (10[1])inversely (10[3])proportional. (10[8])For (10[1])10 points, (10[1])name this (10[1])quantity (10[1])which is (10[1])constant in isothermal (10[1])processes, (10[10]-5[1])measured in rankine (10[1])or kelvin. (10[1])■END■ (10[2])