^{1}

^{1}

^{3}.

In an accelerated expanding universe, one can expect the existence of an event horizon. It may be interesting to study the thermodynamics of the Friedmann-Robertson-Walker (FRW) universe at the event horizon. Considering the usual Hawking temperature, the first law of thermodynamics does not hold on the event horizon. To satisfy the first law of thermodynamics, it is necessary to redefine Hawking temperature. In this paper, using the redefinition of Hawking temperature and applying the first law of thermodynamics on the event horizon, the Friedmann equations are obtained in

The existence of a deep connection between gravity and thermodynamics is one of the greatest discoveries in theoretical physics [

The thermodynamics of the FRW universe bounded by the apparent horizon has been studied by many authors [

In this paper, we are going to apply Hawking temperature redefinition introduced by Tu and Chen in [

Considering a homogeneous and isotropic FRW universe, one can write the metric as follows:

The surface gravity on the apparent horizon is given by

Through the researches about the thermodynamics on the event horizon, Wang et al. found that the thermodynamical description based on the standard definitions of boundary entropy and temperature breaks down in a universe bounded by the cosmological event horizon [

The action of

To derive the Friedmann equation, one can start with the first law of thermodynamics. Using (

Equation (

Applying the usual Hawking temperature, the first law of thermodynamics does not hold on the event horizon. However, using the redefinition of Hawking temperature, it has been shown that the first law of thermodynamics may hold on the event horizon in Einstein gravity and metric

It is now possible to investigate the generalized second law of thermodynamics in the FRW universe bounded by the event horizon in Palatini approach. Considering a universe with the dust energy-momentum tensor in

To investigate GSL, one can substitute

Although the apparent horizon thermodynamics has been studied by many authors in FRW universe, the event horizon thermodynamics is not investigated enough. Since the universe is undergoing an accelerated expansion phase, one may expect the existence of an event horizon. Certainly, the thermodynamics of the event horizon is important to be studied. It has been shown that applying the usual Hawking temperature leads to a nonequilibrium thermodynamics on the event horizon [

No data were used to support this study.

The authors declare that they have no conflicts of interest.