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The existence of a small, non-zero cosmological constant is one of the major puzzles in fundamental physics. Naively, quantum field theory arguments would imply a cosmological constant which is up to 10$^{120}$ times larger than the…

General Physics · Physics 2022-09-08 Michael Bishop , Joey Contreras , Peter Martin , Douglas Singleton

A quantum field theory formalism is reviewed that leads to a self-consistent, finite quantum gravity, Yang-Mills and Higgs theory, which is unitary and gauge invariant to all orders of perturbation theory. The gauge hierarchy problem is…

High Energy Physics - Phenomenology · Physics 2007-05-23 J. W. Moffat

General Relativistic Entropic Acceleration (GREA) theory provides a covariant formalism for out-of-equilibrium phenomena in GR, extending the Einstein equations with an entropic force that behaves like bulk viscosity with a negative…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-28 Juan Garcia-Bellido

In this paper, we demonstrate that the first law of holographic pseudo-entropy, which is a non-Hermitian generalization of entanglement entropy in a two-dimensional conformal field theory (CFT), is equivalent to the perturbative Einstein…

High Energy Physics - Theory · Physics 2025-12-01 Kosei Fujiki , Michitaka Kohara , Kotaro Shinmyo , Yu-ki Suzuki , Tadashi Takayanagi

The cosmological constant problem is one of the greatest challenges in contemporary physics, since it is deeply rooted in the problematic interplay between quantum fields and gravity. The aim of this work is to review the key conceptual…

General Relativity and Quantum Cosmology · Physics 2025-04-23 Federico Scali

Within the holographic cosmology paradigm, specifically the model of McFadden and Skenderis, but more generally than that, the cosmological constant is found to naturally flow from a large value, to a small value, which can even be as low…

High Energy Physics - Theory · Physics 2019-12-25 Horatiu Nastase

It is argued that the so-called holographic principle will obstruct attempts to produce physically realistic models for the unification of general relativity with quantum mechanics, unless determinism in the latter is restored. The notion…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Gerard 't Hooft

This research aims to provide the geometrical foundation of the uncertainty principle within a new causal structure of spacetime so-called Symmetrical Special Relativity (SSR), where there emerges a Lorentz violation due to the presence of…

General Relativity and Quantum Cosmology · Physics 2024-09-10 Cláudio Nassif Cruz

We show that D-dimensional de Sitter space is unstable to the nucleation of non-singular geometries containing spacetime regions with different numbers of macroscopic dimensions, leading to a dynamical mechanism of compactification. These…

High Energy Physics - Theory · Physics 2011-04-14 Sean M. Carroll , Matthew C. Johnson , Lisa Randall

The cosmological constant problem is explained by a theory based on the discrete space-time hypothesis. The calculated cosmological constant value is of the order of 10^-52[m]^-2 or equivalent to about 0.7 of the critical mass density. It…

Astrophysics · Physics 2007-05-23 H. M. Mok

After reviewing the cosmological constant problem - why is Lambda not huge? - I outline the two basic approaches that had emerged by the late 1980s, and note that each made a clear prediction. Precision cosmological experiments now indicate…

High Energy Physics - Theory · Physics 2007-05-23 Raphael Bousso

We present a rigorous theoretical and observational analysis of the Hybrid $ f(Q) $ class of models by including the late-time modifying $ 1/Q $ term. After deriving strict viability conditions from the analytical expansion history, we show…

General Relativity and Quantum Cosmology · Physics 2026-04-15 Ameya Kolhatkar , P. K. Sahoo

It is well-known that quantum field theory (QFT) induces a huge value of the cosmological constant, $\Lambda$, which is outrageously inconsistent with cosmological observations. We review here some aspects of this fundamental theoretical…

General Relativity and Quantum Cosmology · Physics 2022-07-19 Joan Sola Peracaula

Quantum creation of the universe 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 quasi-thermal state which is shown to be…

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

KKLT give a mechanism to generate de Sitter vacua in string theory. And recently, the scenario, {\em landscape}, is suggested to explain the problem of the cosmological constant. In this scenario, the cosmological constant is a de Sitter…

High Energy Physics - Theory · Physics 2009-07-06 C. Y. Sun , D. H. Zhang

We provide a new perspective on the cosmological constant by exploring the background-independent Wheeler-DeWitt quantization of general relativity. The Chern-Simons-Kodama state of quantum gravity, a generalization of the Hartle-Hawking…

General Relativity and Quantum Cosmology · Physics 2025-06-19 Stephon Alexander , Heliudson Bernardo , Aaron Hui

We present a 4-dimensional back reaction analysis of de Sitter space for a conformally coupled scalar field in the presence of vacuum energy initialized in the Bunch-Davies vacuum. In contrast to the usual semi-classical prescription, as…

General Relativity and Quantum Cosmology · Physics 2018-09-25 Tommi Markkanen

The group of Conservative transformations is an enlargement of the group of diffeomorphisms which leads to a richer geometry than that of general relativity. The field variables of the theory are the usual orthonormal tetrads and also…

General Physics · Physics 2016-05-23 Edward Lee Green

The cosmological constant problem is reanalyzed by imposing the limitation of the number of degrees of freedom (d.o.f.) due to entropy bounds directly in the calculation of the energy density of a field theory. It is shown that if a quantum…

High Energy Physics - Theory · Physics 2015-06-05 Paolo Castorina

In a recent Letter, we have pointed out that the linearized Einstein gravity in de Sitter (dS) spacetime besides the spacetime symmetries generated by the Killing vectors and the evident gauge symmetry also possesses a hitherto `hidden'…

General Relativity and Quantum Cosmology · Physics 2019-09-12 Hamed Pejhan , Mohammad Enayati , Jean-Pierre Gazeau , Anzhong Wang