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We present a possible understanding to the issues of cosmological constant, inflation, matter and coincidence problems based only on the Einstein equation and Hawking particle production. The inflation appears and results agree to…

General Physics · Physics 2020-06-26 She-Sheng Xue

We propose a method to extract predictions from quantum cosmology for inflation that can be confronted with observations. Employing the tunneling boundary condition in quantum geometrodynamics, we derive a probability distribution for the…

General Relativity and Quantum Cosmology · Physics 2015-07-21 Gianluca Calcagni , Claus Kiefer , Christian F. Steinwachs

Cosmological models with inflation and those with bounce have their own strengths and weaknesses. Here we construct a model in which a phase of bounce is followed by a viable inflationary phase. This incorporates several advantages of both…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-02 Manjeet Kaur , Debottam Nandi , Debajyoti Choudhury , T. R. Seshadri

A precise measurement of the curvature of the Universe is of primeval importance for cosmology since it could not only confirm the paradigm of primordial inflation but also help in discriminating between different early Universe scenarios.…

Cosmology and Nongalactic Astrophysics · Physics 2021-05-27 Eleonora Di Valentino , Luis A. Anchordoqui , Ozgur Akarsu , Yacine Ali-Haimoud , Luca Amendola , Nikki Arendse , Marika Asgari , Mario Ballardini , Spyros Basilakos , Elia Battistelli , Micol Benetti , Simon Birrer , François R. Bouchet , Marco Bruni , Erminia Calabrese , David Camarena , Salvatore Capozziello , Angela Chen , Jens Chluba , Anton Chudaykin , Eoin Ó Colgáin , Francis-Yan Cyr-Racine , Paolo de Bernardis , Javier de Cruz Pérez , Jacques Delabrouille , Celia Escamilla-Rivera , Agnès Ferté , Fabio Finelli , Wendy Freedman , Noemi Frusciante , Elena Giusarma , Adrià Gómez-Valent , Will Handley , Ian Harrison , Luke Hart , Alan Heavens , Hendrik Hildebrandt , Daniel Holz , Dragan Huterer , Mikhail M. Ivanov , Shahab Joudaki , Marc Kamionkowski , Tanvi Karwal , Lloyd Knox , Suresh Kumar , Luca Lamagna , Julien Lesgourgues , Matteo Lucca , Valerio Marra , Silvia Masi , Sabino Matarrese , Arindam Mazumdar , Alessandro Melchiorri , Olga Mena , Laura Mersini-Houghton , Vivian Miranda , Cristian Moreno-Pulido , David F. Mota , Jessica Muir , Ankan Mukherjee , Florian Niedermann , Alessio Notari , Rafael C. Nunes , Francesco Pace , Andronikos Paliathanasis , Antonella Palmese , Supriya Pan , Daniela Paoletti , Valeria Pettorino , Francesco Piacentini , Vivian Poulin , Marco Raveri , Adam G. Riess , Vincenzo Salzano , Emmanuel N. Saridakis , Anjan A. Sen , Arman Shafieloo , Anowar J. Shajib , Joseph Silk , Alessandra Silvestri , Martin S. Sloth , Tristan L. Smith , Joan Solà , Carsten van de Bruck , Licia Verde , Luca Visinelli , Benjamin D. Wandelt , Deng Wang , Jian-Min Wang , Anil K. Yadav , Weiqiang Yang

For two decades the hot big-bang model has been referred to as the standard cosmology -- and for good reason. For just as long cosmologists have known that there are fundamental questions that are not addressed by the standard cosmology and…

Astrophysics · Physics 2007-05-23 Michael S. Turner

The physical basis of the modern cosmological inflationary models with baryosynthesis and nonbaryonic dark matter and energy implies such predictions of particle theory, that, in turn, apply to cosmology for their test. It makes physics of…

Astrophysics · Physics 2007-05-23 Maxim Yu. Khlopov

The matter bounce scenario allows for a sizable parameter space where cosmological fluctuations originally exited the Hubble radius when the background energy density was small. In this scenario and its extended versions, the low energy…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-02 Yi-Fu Cai , Francis Duplessis , Damien A. Easson , Dong-Gang Wang

The theory of cosmological perturbations has become a cornerstone of modern quantitative cosmology since it is the framework which provides the link between the models of the very early Universe such as the inflationary Universe scenario…

High Energy Physics - Theory · Physics 2017-08-23 Robert H. Brandenberger

The standard model of cosmology is based on the hot Big Bang theory and the inflationary paradigm. Recent precise observations of the temperature and polarization anisotropies in the cosmic microwave background and the matter distribution…

High Energy Physics - Phenomenology · Physics 2016-10-05 Juan Garcia-Bellido

Bouncing models of cosmology, as they arise e.g. in loop quantum cosmology, can be followed by an inflationary phase and generate close-to-scale-invariant fluctuation spectra as observed in the Cosmic Microwave Background (CMB). However,…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-12 Bartjan van Tent , Paola C. M. Delgado , Ruth Durrer

CMB anisotropy data could put powerful constraints on theories of the evolution of our Universe. Using the observations of the large number of CMB experiments, many studies have put constraints on cosmological parameters assuming different…

Astrophysics · Physics 2015-06-24 Marian Douspis

We review the current standard model for the evolution of the Universe from an early inflationary epoch to the complex hierarchy of structure seen today. We summarize and provide key references for the following topics: observations of the…

Astrophysics · Physics 2009-06-23 Bharat Ratra , Michael S. Vogeley

We examine the dynamics of a closed cosmology whose matter source is that of a conformally coupled scalar field with a broken ${\rm SO}(1,1)$ symmetry, which correspond to the $\alpha$-attractors proposed by Linde and Kallosh. Following a…

General Relativity and Quantum Cosmology · Physics 2020-02-19 David Sloan , Konstantinos Dimopoulos , Sotirios Karamitsos

A bouncing scenario of a flat homogeneous and isotropic universe is explored by using the reconstruction technique for the power-law parametrization of the Hubble parameter in a modified gravity theory with higher-order curvature and trace…

General Relativity and Quantum Cosmology · Physics 2023-04-03 J. K. Singh , Harshna Balhara , Kazuharu Bamba , J. Jena

We explore a model of the early universe in which the inflationary epoch is preceded by a cosmic bounce, and argue that this scenario provides a common origin to several of the anomalous features that have been observed at large angular…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-17 Ivan Agullo , Dimitrios Kranas , V. Sreenath

In the past decade, the importance of dissipation and fluctuation to inflationary dynamics has been realized and has led to a new picture of inflation called warm inflation. Although these phenomena are common to condensed matter systems,…

High Energy Physics - Phenomenology · Physics 2009-11-13 Arjun Berera

Cosmology is undergoing an explosive period of activity, fueled both by new, accurate astrophysical data and by innovative theoretical developments. Cosmological parameters such as the total density of the Universe and the rate of…

Astrophysics · Physics 2007-05-23 A. S. Sakharov , H. Hofer

As an alternative to the paradigm of slow roll inflation, we propose an extended scenario of the matter bounce cosmology in which the Universe has experienced a quasi-matter contracting phase with a variable background equation of state…

General Relativity and Quantum Cosmology · Physics 2015-09-04 Jaume de Haro , Yi-Fu Cai

Although the current galaxy models yield calculations consistent with much of the data, many irregularities exist, exceptions have been found to the current models, the $\Lambda$CDM model apparently fails on galaxy scales, dark matter…

Astrophysics · Physics 2007-05-23 John C. Hodge

We suggest an alternative framework for interpreting the current state of the visible universe. Our approach is based on a dynamical ``Cosmological Constant'' and the starting point is that a decaying vacuum produces matter. As we point…

Astrophysics · Physics 2014-10-13 Manasse R. Mbonye