عنوان مجله
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INTERNATIONAL JOURNAL OF THEORETICAL PHYSICS
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چکیده
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Recently, it was argued (Tsallis and Cirto, Eur. Phys. J. C 73, 2487 2013) that
the total entropy of a gravitational system should be related to the volume of system instead
of the system surface. Here, we show that this new proposal cannot satisfy the unified first
law of thermodynamics and the Friedmans equation simultaneously, unless the effects of
dark energy candidate on the horizon entropy are considered. In fact, our study shows that
some types of dark energy candidate may admit this proposal. Some general properties of
required dark energy are also addressed. Moreover, our investigation shows that this new
proposal for entropy, while combined with the second law of thermodynamics (as the backbone
of Verlinde’s proposal), helps us in provideing a thermodynamic interpretation for the
difference between the surface and bulk degrees of freedom which, according to Padmanabhan’s
proposal, leads to the emergence of spacetime and thus the universe expansion. In
fact, our investigation shows that the entropy changes of system may be equal to the difference
between the surface and bulk degrees of freedom falling from surface into the system
volume. Briefly, our results signal us that this new proposal for entropy may be in agreement
with the thermodynamics laws, the Friedmann equation, Padmanabhan’s holographic proposal
for the emergence of spacetime and therefore the universe expansion. In fact, this new
definition of entropy may be used to make a bridge between Verlinde’s and Padmanabhan’s
proposals.
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