In a recent article on Tsallis entropy in the latest edition of Physics World, I found the discussion rather diverting.
Tsallis entropy in some ways modifies the Boltzmann-Gibbs entropy, because, as Tsallis claims, for correlated systems (where possible microstates may be correlated) the entropy law needs a slightly different nature.
According to Tsallis, entropy is an extensive property (dependent on the dimension of the system in a way) as opposed to intensive property such as temperature (which is independent of the mass of the material, barring of course during a change process). He further claims this extenisve property and the law relating temperature and entropy can be violated in correlated systems. Hence for such systems a new/modified law is required.
This view (as I understood) is strongly dependent on the belief of the extensive nature of entropy. While some oppponents of the Tsallis entropy claim it violates the zero-th law of thermodynamics. Which of these is sacrosant?
I do not know the answer. What I find very intriguing about this debate is (the concept itself, because it draws inspiration from self similar and fractal curves) and also the fact that based on which previous theory one holds sacerd, one’s views change. But is any Physics principle or theory really sacrosanct? Who is to say when (in the distant future) something we believe to be absolutely correct now shall be proved wrong/special case?