Is The Internal Entropy of F(R)-Gravity Really An Entropy?

This paper connects two methods for finding the functional of entropy in F(R)-Gravity: Padmanabhan’s and Hammad’s. The resulting approach is simple to follow and yields the expected entropy functional. This functional can be separated into two parts. The part unknown in General Relativity is identified with internally developed entropy. This paper points on incompatibility between the internal entropy found from the entropy functional and the entropy found using conventional approach from equations of motion.