Related papers: Reconsidering the horizon problem
The second law and the generalized second law of thermodynamics in cosmology in the framework of the modified Gauss-Bonnet theory of gravity are investigated. The conditions upon which these laws hold are derived and discussed.
The research work in the thesis is focused on the thermodynamic analysis of cosmological models, especially the models that explain late-time cosmic acceleration. According to the cosmological principle, the universe is spatially…
We contrast the possibility of inflation starting a) from the universe's inception or b) from an earlier non-inflationary state. Neither case is ideal since a) assumes quantum mechanical reasoning is straightforwardly applicable to the…
This paper studies intermediate homogenization of inhomogeneous cosmological models. It shows that spherically symmetric models, regardless of the equation of state, can undergo intermediate homogenization, i.e. a model can approach a…
We pointed out that the generalized second law of thermodynamics on a de Sitter universe whose energy density stochastically fluctuates due to quantum fluctuations is seemingly violated. We have shown that even in such a case, the…
A dependence of low energy physics on initial conditions in the framework of multidimensional gravity is discussed. It is shown that the observable symmetries could be a result of specific topologies originated from space-time foam.
In this essay, we discuss the fine-tuning problems of the Higgs mass and the cosmological constant. We argue that these are indeed legitimate problems, as opposed to some other "problems" that are sometimes described using similar…
The paper deals with universal thermodynamics for FRW model of the universe bounded by apparent (or event) horizon. Assuming Hawking temperature on the horizon, the unified first law is examined on the horizon for different gravity…
The first part of this paper is a condensed synthesis of the matter presented in several previous ones. It begins with an argumentation showing that the first and second laws of thermodynamics are incompatible with one another if they are…
Thermodynamics on the horizon of a flat universe at late times is studied in holographic cosmological models that assume an associated entropy on the horizon. In such models, a $\Lambda(t)$ model similar to a time-varying $\Lambda(t)$…
In this paper, we examine the validity of the generalized second law of thermodynamics (GSLT) of the universe bounded by the event horizon in brane-world gravity. Here we consider homogeneous and isotropic model of the universe filled with…
We have investigated the thermodynamical properties of the universe with dark energy. It is demonstrated that in a universe with spacial curvature the natural choice for IR cutoff could be the apparent horizon radius. We shown that any…
Expansion of the universe is caused by the departure from the holographic equipartition. This principle, the law of emergence, first postulated in the context of Einstein's gravity has been extended successfully to more general gravity…
Starting from the first law of thermodynamics, $dE=T_hdS_h+WdV$, at apparent horizon of a FRW universe, and assuming that the associated entropy with apparent horizon has a quantum corrected relation, $S=\frac{A}{4G}-\alpha \ln…
Universal thermodynamics for FRW model of the Universe bounded by apparent/event horizon has been considered for massive gravity theory. Assuming Hawking temperature and using the unified first law of thermodynamics on the horizon, modified…
It is shown that the differential form of Friedmann equations of FRW universe can be recast as a similar form of the first law, $T_{h}dS_{h} = dE + WdV$, of thermodynamics at the apparent horizon of FRW universe filled with the viscous…
Time-symmetric cosmological theories, in which the initial and final states are arranged to have similar features or are independently fixed, have been quite extensively discussed in the literature. However, a more general and perhaps more…
In this work, we have investigated the validity of the generalized second law of thermodynamics in logamediate and intermediate scenarios of the universe bounded by the Hubble, apparent, particle and event horizons using and without using…
Motivated by the notion that the mathematics of gravity can be reproduced from a statistical requirement of maximal entropy, we study the consequence of introducing an entropic source term in the Einstein-Hilbert action. For a spatially…
A classical and quantum mechanical generalized second law of thermodynamics in cosmology implies constraints on the effective equation of state of the universe in the form of energy conditions, obeyed by many known cosmological solutions,…