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We suggest a novel picture of the quantum Universe -- its creation is described by the {\em density matrix} defined by the Euclidean path integral. This yields an ensemble of universes -- a cosmological landscape -- in a mixed state which…

High Energy Physics - Theory · Physics 2009-11-11 A. O. Barvinsky , A. Yu. Kamenshchik

The creation of a quantum Universe is described by a {\em density matrix} which yields an ensemble of universes with the cosmological constant limited to a bounded range $\Lambda_{\rm min}\leq \Lambda \leq \Lambda_{\rm max}$. The domain…

High Energy Physics - Theory · Physics 2008-11-26 A. O. Barvinsky , A. Yu. Kamenshchik

In the framework of the Hartle-Hawking no-boundary proposal, we investigated quantum creation of the multidimensional universe with a cosmological constant ($\Lambda$) but without matter fields. We have found that the classical solutions of…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Hirotaka Ochiai , Katsuhiko Sato

When the semi-positive cosmological constant is dynamical, the naive Euclidean Einstein action is unbounded from below and the Hartle-Hawking wavefunction of the universe is not normalizable. With the inclusion of back-reaction (a crucial…

High Energy Physics - Theory · Physics 2007-05-23 Saswat Sarangi , S. -H. Henry Tye

We present an overview of a recently suggested new model of quantum initial conditions for the Universe in the form of a cosmological density matrix. This density matrix originally suggested in the Euclidean quantum gravity framework turns…

High Energy Physics - Theory · Physics 2008-11-03 A. O. Barvinsky , C. Deffayet , A. Yu. Kamenshchik

Quantum Action Principle which has been used as a ground for a probabilistic interpretation of one-particle relativistic quantum mechanics \cite{GLL} is applied to quantum cosmology. The quantum creation of matter in a minisuperspace model…

General Relativity and Quantum Cosmology · Physics 2011-05-11 Natalia Gorobey , Alexander Lukyanenko

A complete model of the universe needs at least three parts: (1) a complete set of physical variables and dynamical laws for them, (2) the correct solution of the dynamical laws, and (3) the connection with conscious experience. In quantum…

High Energy Physics - Theory · Physics 2007-05-23 Don N. Page

The semi-classical approach to the quantum geometrodynamical model is used for the description of the properties of the universe on extremely small spacetime scales. Quantum theory for a homogeneous, isotropic and closed universe is…

General Relativity and Quantum Cosmology · Physics 2009-10-21 V. E. Kuzmichev , V. V. Kuzmichev

The path integral over Euclidean geometries for the recently suggested density matrix of the Universe is shown to describe a microcanonical ensemble in quantum cosmology. This ensemble corresponds to a uniform (weight one) distribution in…

High Energy Physics - Theory · Physics 2008-11-26 A. O. Barvinsky

In this paper it is studied the cosmology of a homogeneous and isotropic spacetime endorsed with a conformally coupled massless scalar field. We find six different solutions of the Friedmann equation that represent six different types of…

General Relativity and Quantum Cosmology · Physics 2017-09-20 Salvador J. Robles-Perez

The probable trajectory of the ground state wave function of the universe arises through a quantum tunneling by gravitational instantons. We calculate the quantum tunneling rate for a $n>2$ dimensional closed Friedmann-Robertson-Walker…

General Relativity and Quantum Cosmology · Physics 2013-05-16 F. Darabi , S. Jalalzadeh

Universe structure emerges in the unreduced, complex-dynamical interaction process with the simplest initial configuration (two attracting homogeneous fields). The unreduced interaction analysis avoiding any perturbative model gives…

General Physics · Physics 2015-03-20 Andrei P. Kirilyuk

The observable universe is fundamentally inhomogeneous and anisotropic. Quantum description of the generation of these inhomogeneities and anisotropies is ill-understood and unsatisfactory. After providing a brief account of the standard…

General Relativity and Quantum Cosmology · Physics 2024-04-05 Sujoy K. Modak

A proposal is made for the quantum state of the universe that has an initial state that is macroscopically time symmetric about a homogeneous, isotropic bounce of extremal volume and that at that bounce is microscopically in the ground…

High Energy Physics - Theory · Physics 2015-05-13 Don N. Page

Universe structure emerges in the unreduced, complex-dynamic interaction process with the simplest initial configuration (two attracting homogeneous fields, quant-ph/9902015). The unreduced interaction analysis gives intrinsically creative…

General Physics · Physics 2007-05-23 Andrei P. Kirilyuk

Quantum cosmology uses a wave function to model the universe, but finding solutions for this poses a problem as it is difficult to define the boundary conditions or identify the correct path for a path integral. We begin the discussion by…

General Relativity and Quantum Cosmology · Physics 2022-11-10 Alisha Marriott-Best

The process of quantum creation of a qusihomogeneous inflationary universe near a cosmological singularity is considered. It is shown that during the evolution quantum fluctuations of spatial topologies increase and the universe acquires…

General Relativity and Quantum Cosmology · Physics 2007-05-23 A. A. Kirillov

In the action formalism variations of metric tensors usually are limited by the Hubble horizon. Contrary, variations of quantum fields should be extended up to the event horizon, which is the real boundary of the spacetime. As the result…

General Physics · Physics 2018-11-29 Merab Gogberashvili

We provide a cosmological implementation of the evolutionary quantum gravity, describing an isotropic Universe, in the presence of a negative cosmological constant and a massive (preinflationary) scalar field. We demonstrate that the…

General Relativity and Quantum Cosmology · Physics 2015-06-22 Francesco Cianfrani , Giovanni Montani , Fabrizio Pittorino

A complete model of the universe needs at least three parts: (1) a complete set of physical variables and dynamical laws for them, (2) the correct solution of the dynamical laws, and (3) the connection with conscious experience. In quantum…

High Energy Physics - Theory · Physics 2007-05-23 Don N. Page
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