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In this approach to discrete quantum gravity the basic structural element is a covariant causal set ($c$-causet). The geometry of a $c$-causet is described by a shell-sequence that determines the discrete gravity of a universe. In this…

General Relativity and Quantum Cosmology · Physics 2015-07-07 Stan Gudder

The basic workings of inflationary models are summarized, along with the arguments that strongly suggest that our universe is the product of inflation. I describe the quantum origin of density perturbations, giving a heuristic derivation of…

Astrophysics · Physics 2007-05-23 Alan H. Guth

In this work we construct a bottom-up reconstruction technique for Loop Quantum Cosmology scalar-tensor theories, from the observational indices. Particularly, the reconstruction technique is based on fixing the functional form of the…

General Relativity and Quantum Cosmology · Physics 2018-05-02 Jaume de Haro , S. D. Odintsov , V. K. Oikonomou

Fundamental formulae representing the density perturbation spectrums generated in inflationary scenarios are rigorously proved. Quantum fluctuations as initial conditions for structure generation in some inflationary era can be calculated…

Astrophysics · Physics 2008-11-26 J. Hwang

We are interested in the problem of characterizing the correlations that arise when performing local measurements on separate quantum systems. In a previous work [Phys. Rev. Lett. 98, 010401 (2007)], we introduced an infinite hierarchy of…

Quantum Physics · Physics 2009-01-16 Miguel Navascues , Stefano Pironio , Antonio Acin

We investigate the quantumness of primordial cosmological fluctuations and its detectability. The quantum discord of inflationary perturbations is calculated for an arbitrary splitting of the system, and shown to be very large on…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-29 Jerome Martin , Vincent Vennin

The problem of using observed correlations to infer causal relations is relevant to a wide variety of scientific disciplines. Yet given correlations between just two classical variables, it is impossible to determine whether they arose from…

Multi-class systems having possibly both finite and infinite classes are investigated under a natural partial exchangeability assumption. It is proved that the conditional law of such a system, given the vector of the empirical measures of…

Probability · Mathematics 2009-02-04 Carl Graham

It has long been recognized that certain quantum correlations are incompatible with particular assumption about classical causal structure. Given a causal structure of unknown classicality, the presence of such correlations certifies the…

Quantum Physics · Physics 2020-08-19 Thomas C. Fraser , Elie Wolfe

Within the field of causal inference, it is desirable to learn the structure of causal relationships holding between a system of variables from the correlations that these variables exhibit; a sub-problem of which is to certify whether or…

Other Statistics · Statistics 2020-10-26 Thomas C. Fraser

The theory of inflation provides a mechanism to explain the structures we observe today in the Universe, starting from quantum-mechanically generated fluctuations. However, this leaves the question of: how did the quantum-to-classical…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-16 Jessie de Kruijf , Nicola Bartolo

This paper presents a framework for Quantum causal modeling based on the interpretation of causality as a relation between an observer's probability assignments to hypothetical or counterfactual experiments. The framework is based on the…

Quantum Physics · Physics 2020-01-15 Jacques Pienaar

Inferring causal relationships from observational data is rarely straightforward, but the problem is especially difficult in high dimensions. For these applications, causal discovery algorithms typically require parametric restrictions or…

Methodology · Statistics 2022-06-29 David S. Watson , Ricardo Silva

The early Universe inflation is well known as a promising theory to explain the origin of large scale structure of the Universe, a causal theory for the origin of primordial density fluctuations which may explain the observed density…

Astrophysics · Physics 2007-05-23 Xin-he Meng

We discuss the classicalization of a quantum state induced by an environment in the inflationary stage of the universe. The classicalization is necessary for the homogeneous ground sate to become classical non-homogeneous one accompanied…

General Relativity and Quantum Cosmology · Physics 2009-10-30 H. Kubotani , T. Uesugi , M. Morikawa , A. Sugamoto

The decoherence of quantum fluctuations into classical perturbations during inflation is discussed. A simple quantum mechanical argument, using a spatial particle wavefunction rather than a field description, shows that observable…

Astrophysics · Physics 2007-05-23 Craig J. Hogan

Attempts to apply quantum collapse theories to Cosmology and cosmic inflation are reviewed. These attempts are motivated by the fact that the theory of cosmological perturbations of quantum-mechanical origin suffers from the single outcome…

Quantum Physics · Physics 2021-04-14 Jerome Martin , Vincent Vennin

Popular wisdom suggests that measuring the tensor to scalar ratio $r$ on CMB scales is a "proof of inflation" since one generic prediction is a scale-invariant tensor spectrum while alternatives predict $r$ that is many orders of magnitude…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-15 Ido Ben-Dayan , Udaykrishna Thattarampilly

Although the paradigm of inflation has been extensively studied to demonstrate how macroscopic inhomogeneities in our universe originate from quantum fluctuations, most of the established literature ignores the crucial role that…

High Energy Physics - Theory · Physics 2022-11-30 Suddhasattwa Brahma , Arjun Berera , Jaime Calderón-Figueroa

We investigate the quantum cosmological tunneling scenario for inflationary models. Within a path-integral approach, we derive the corresponding tunneling probability distribution. A sharp peak in this distribution can be interpreted as the…

General Relativity and Quantum Cosmology · Physics 2014-10-15 Gianluca Calcagni , Claus Kiefer , Christian F. Steinwachs