Comment on Tsallis, C. Black Hole Entropy: A Closer Look. <em>Entropy </em>2020, <em>22</em>, 17

Abstract

In a recent paper (Entropy 2020, 22(1), 17), Tsallis states that entropy—as in Shannon or Kullback–Leiber’s definitions—is inadequate to interpret black hole entropy and suggests that a new non-additive functional should take the role of entropy. Here we counterargue by explaining the important distinction between the properties of extensivity and additivity; the latter is fundamental for entropy, while the former is a property of particular thermodynamical systems that is not expected for black holes. We also point out other debatable statements in his analysis of black hole entropy.

Keywords

• black holes
• entropy
• non-additive entropies
• thermodynamics
• inference