Phase transitions, critical behavior and microstructure of the FRW universe in the framework of higher order GUP

Abstract

In this paper, we explore the the phase transition, critical behavior and microstructure of the FRW in the framework of a new higher order generalized uncertainty principle. Our initial step involves deriving the equation of state by defining the work density $W$ from GUP-corrected Friedmann equations as the thermodynamic pressure $P$. Based on the modified equation of state, we conduct an analysis of the $P-V$ phase transition in the FRW universe. Subsequently, we obtain the critical exponents and coexistence curves for the small and large phases of the FRW universe around the critical point. Finally, employing Ruppeiner geometry, we derive the thermodynamic curvature scalar $R_N$, investigating its sign-changing curve and spinodal curve. The results reveal distinctive thermodynamic properties for FRW universes with positive and negative GUP parameters $\beta$. In the case of $\beta>0$, the phase transition, critical behavior and microstructure of FRW universe are consistent with those of Van der Waals fluids. Conversely, for $\beta<0$, the results resemble those obtained through effective scalar field theory. These findings underscore the capacity of quantum gravity to induce phase transitions in the universe, warranting further in-depth exploration.