Friedmann equations from GUP-modified equipartition law

Abstract

In this paper, combining the thermodynamical arguments of the horizon with the quadratic generalised uncertainty principle (GUP), we heuristically obtain the modified equipartition law of energy. Employing this modified equipartition law of energy, we derive the Friedmann equations in Verlinde's entropic gravity. We find a maximum energy density at the beginning of the Universe. Remarkably, this feature emerges not only for positive GUP parameter but also for negative GUP parameter. From the initial acceleration, we deduce that the negative GUP parameter is more preferable. We also obtain maximum Hubble parameter from the first Friedmann equation, indicating a universe without initial singularity. Moreover, we compute the Kretschmann curvature scalar, again indicating a non-singular universe. Interestingly, we find that GUP-modified Friedmann equations share some similarities with braneworld cosmolgy where the quadratic term in energy density appears. We also compute the deceleration parameter. Finally, we revisit the gravitational baryogenesis and show that the GUP-modified equipartition law of energy provides a mechanism for generating baryon asymmetry. Moreover, we constrain the GUP parameter from observations.