The discussion centers on whether the logarithm of the number of molecules (ln N) qualifies as a thermodynamic state variable. Participants agree that while the number of molecules (N) is a state variable, the logarithm may not be considered one since it is a mathematical function rather than a physical quantity. The conversation also touches on the nature of state variables, emphasizing that they describe inherent properties of a thermodynamic system. Additionally, there is a query about whether melting and boiling points are state variables, with some arguing they provide essential information about the system despite being uncontrollable. Overall, the distinction between physical quantities and their mathematical representations is a key focus.