MOND Theory and Thermodynamics of Spacetime

Abstract

Starting from the Modified Newtonian Dynamics (MOND) theory and using an inverse approach, we construct a general form of the entropy expression associated with the horizon based on the entropic nature of gravity. Using the thermodynamics-gravity correspondence in the cosmological setup, we apply the corrected entropy expression and find the modified Friedmann equation by three methods, namely, (i) the first law of thermodynamics, (ii) the entropic force scenario and (iii) the emergence nature of gravity. We confirm that our model guaranties the generalized second law of thermodynamics for the universe enveloped by the apparent horizon. Our studies reveal that the MOND theory of gravity may be naturally deduced from the modification of the horizon entropy. These results may fill in the gap in the literatures, understanding the theoretical origin of the MOND theory from thermodynamics-gravity conjecture.