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Within the framework of an eternal inflationary scenario, a natural question regarding the production of eternal bubbles is the essential condition requires to have a universe capable of generating life. In either an open or a closed…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-30 Sohrab Rahvar

We speculate that the early Universe was inside a primordial black hole. The interior of the the black hole is a dS background and the two spacetimes are separated on the surface of black hole's event horizon. We argue that this picture…

High Energy Physics - Theory · Physics 2016-10-13 Hassan Firouzjahi

The hypothesis of low entropy in the initial state of the universe usually explains the observed entropy increase is in only one time direction: the thermodynamic arrow of time. The Hamiltonian formalism is commonly used in the context of…

General Relativity and Quantum Cosmology · Physics 2024-08-27 Jackie C. H. Liu

Inflationary cosmology has, in the last few years,received a strong dose of support from observations. The fact that the fluctuation spectrum can be extracted from the inflationary scenario through an analysis that involves quantum field…

General Relativity and Quantum Cosmology · Physics 2009-07-24 Daniel Sudarsky , Adolfo De Unanue

A rapid phase of accelerated expansion in the early universe, known as inflation, dilutes all matter except the vacuum induced quantum fluctuations. These are responsible for seeding the initial perturbations in the baryonic matter, the…

High Energy Physics - Phenomenology · Physics 2011-06-28 Anupam Mazumdar

A wide variety of vacua, and their cosmological realization, may provide an explanation for the apparently anthropic choices of some parameters of particle physics and cosmology. If the probability on various parameters is weighted by…

High Energy Physics - Theory · Physics 2008-11-26 Lawrence J. Hall , Taizan Watari , T. T. Yanagida

According to statistical mechanics, micro-states of an isolated physical system (say, a gas in a box) at time $t_0$ in a given macro-state of less-than-maximal entropy typically evolve in such a way that the entropy at time $t$ increases…

Cosmology and Nongalactic Astrophysics · Physics 2016-07-27 Sheldon Goldstein , Roderich Tumulka , Nino Zanghi

A brief review of the modern state of quantum cosmology is presented as a theory of quantum initial conditions for inflationary scenario. The no-boundary and tunneling states of the Universe are discussed as a possible source of probability…

General Relativity and Quantum Cosmology · Physics 2017-08-23 A. O. Barvinsky

Cosmic inflation provides a window to the highest energy densities accessible in nature, far beyond those achievable in any realistic terrestrial experiment. Theoretical insights into the inflationary era and its observational probes may…

A very simplified model of the Universe is considered in order to propose an alternative approach to the irreversible evolution of the Universe at very early times. The entropy generation at the quantum stage can be thought as a consequence…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Mario A. Castagnino , Fabian H. Gaioli , Daniel M. Sforza

It was recently shown that gravitons with a very small mass should have formed a Bose-Einstein condensate in the very early Universe, whose density and quantum potential can account for the dark matter and dark energy in the Universe…

General Relativity and Quantum Cosmology · Physics 2015-10-13 Saurya Das

The scalar field is considered to have dominated the early Universe. One subtle yet crucial requirement of this assumption is that the solution must be highly stable, i.e., indifferent to any initial conditions because there are no favored…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-23 Debottam Nandi , Manjeet Kaur

The current status of early universe cosmology can be summarized as precision, but inherently limited, data requiring explanation from precision and robust theory. Specifically inflation is presently the single concrete hope for solving the…

High Energy Physics - Phenomenology · Physics 2009-11-07 Arjun Berera

We note that the observable part of universe at a certain time t_P is necessarily limited, when there is a beginning of universe. We argue that an appropriate spacetime region associated with an observer from tI to t_P is the causal diamond…

General Relativity and Quantum Cosmology · Physics 2015-06-12 Dongsu Bak

We investigate cosmological solutions for the modified gravity theory obtained from quantum relative entropy between the metric of spacetime and the metric induced by the geometry and matter fields. The vacuum equations admit inflationary…

General Relativity and Quantum Cosmology · Physics 2025-12-23 Udaykrishna Thattarampilly , Yunlong Zheng

Inflationary models are generally credited with explaining the large scale homogeneity, isotropy, and flatness of our universe as well as accounting for the origin of structure (i.e., the deviations from exact homogeneity) in our universe.…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Stefan Hollands , Robert M. Wald

The inflationary scenario, which states that the early universe underwent a brief but dramatic period of accelerated spatial expansion, has become the current paradigm of early universe cosmology. Although inflationary cosmology has its…

General Relativity and Quantum Cosmology · Physics 2024-06-04 Eric Ling , Annachiara Piubello

There is something missing in our understanding of the origin of the seeds of Cosmic Structuture. The fact that the fluctuation spectrum can be extracted from the inflationary scenario through an analysis that involves quantum field theory…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Daniel Sudarsky

A new definition of entropy is introduced using a model that simulates an expanding space-time compatible with the fundamental principle of cosmology. The entropy is obtained by mean of a state function that measures the variation of the…

General Physics · Physics 2024-05-01 Faycal Ben Adda

This contribution inquires into Clausius' proposal that "the entropy of the world tends to a maximum.'" The question is raised whether the entropy of "the world" actually does have a maximum; and if the answer is "Yes!," what such states of…

History and Philosophy of Physics · Physics 2019-06-11 Michael K. -H. Kiessling