scholarly journals Fuzzy Instantons in Landscape and Swampland: Review of the Hartle–Hawking Wave Function and Several Applications

Universe ◽  
2021 ◽  
Vol 7 (10) ◽  
pp. 367
Author(s):  
Dong-han Yeom
Keyword(s):  
Black Hole ◽  
Wave Function ◽  
Path Integral ◽  
Initial Conditions ◽  
Black Hole Physics ◽  
Slow Roll ◽  
Potential Shape ◽  
Euclidean Wormholes ◽  
The Universe ◽  
Origin Of The Universe

The Euclidean path integral is well approximated by instantons. If instantons are dynamical, they will necessarily be complexified. Fuzzy instantons can have multiple physical applications. In slow-roll inflation models, fuzzy instantons can explain the probability distribution of the initial conditions of the universe. Although the potential shape does not satisfy the slow-roll conditions due to the swampland criteria, the fuzzy instantons can still explain the origin of the universe. If we extend the Euclidean path integral beyond the Hartle–Hawking no-boundary proposal, it becomes possible to examine fuzzy Euclidean wormholes that have multiple physical applications in cosmology and black hole physics.

scholarly journals THE WAVE FUNCTION OF THE UNIVERSE BY THE NEW EUCLIDEAN PATH-INTEGRAL APPROACH IN QUANTUM COSMOLOGY

1993 ◽  
Vol 02 (02) ◽  
pp. 249-256 ◽  
Author(s):  
ATUSHI ISHIKAWA ◽  
HARUHIKO UEDA
Keyword(s):  
Wave Function ◽  
Path Integral ◽  
Regularization Method ◽  
Positive Definite ◽  
Integral Approach ◽  
Type I ◽  
Path Integral Approach ◽  
The Universe ◽  
Friedmann Robertson Walker ◽  
Hilbert Action

The wave function of the universe is evaluated by using the Euclidean path integral approach. As is well known, the real Euclidean path integral diverges because the Einstein-Hilbert action is not positive definite. In order to obtain a finite wave function, we propose a new regularization method and calculate the wave function of the Friedmann-Robertson-Walker type minisuperspace model. We then consider a homogeneous but anisotropic type minisuperspace model, which is known as the Bianch type I model. The physical meaning of the wave function by this new regularization method is also examined.

scholarly journals Baryogenesis from ultra-slow-roll inflation

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
Yi-Peng Wu ◽  
Elena Pinetti ◽  
Kalliopi Petraki ◽  
Joseph Silk
Keyword(s):  
Dark Matter ◽  
Initial Conditions ◽  
Coherent Motion ◽  
Primordial Black Hole ◽  
Coincidence Problem ◽  
Effective Potentials ◽  
Slow Roll ◽  
Single Field ◽  
Rolling Rate ◽  
The Universe

Abstract The ultra-slow-roll (USR) inflation represents a class of single-field models with sharp deceleration of the rolling dynamics on small scales, leading to a significantly enhanced power spectrum of the curvature perturbations and primordial black hole (PBH) formation. Such a sharp transition of the inflationary background can trigger the coherent motion of scalar condensates with effective potentials governed by the rolling rate of the inflaton field. We show that a scalar condensate carrying (a combination of) baryon or lepton number can achieve successful baryogenesis through the Affleck-Dine mechanism from unconventional initial conditions excited by the USR transition. Viable parameter space for creating the correct baryon asymmetry of the Universe naturally incorporates the specific limit for PBHs to contribute significantly to dark matter, shedding light on the cosmic coincidence problem between the baryon and dark matter densities today.

scholarly journals Wormholes and black hole microstates in AdS/CFT

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Jordan Cotler ◽  
Kristan Jensen
Keyword(s):  
Black Hole ◽  
Density Of States ◽  
Integral Transformation ◽  
Black Hole Physics ◽  
Einstein Gravity ◽  
Coarse Grained ◽  
Hole Density ◽  
Saddle Point Approximation ◽  
Level Statistics ◽  
Euclidean Wormholes

Abstract It has long been known that the coarse-grained approximation to the black hole density of states can be computed using classical Euclidean gravity. In this work we argue for another entry in the dictionary between Euclidean gravity and black hole physics, namely that Euclidean wormholes describe a coarse-grained approximation to the energy level statistics of black hole microstates. To do so we use the method of constrained instantons to obtain an integral representation of wormhole amplitudes in Einstein gravity and in full-fledged AdS/CFT. These amplitudes are non-perturbative corrections to the two-boundary problem in AdS quantum gravity. The full amplitude is likely UV sensitive, dominated by small wormholes, but we show it admits an integral transformation with a macroscopic, weakly curved saddle-point approximation. The saddle is the “double cone” geometry of Saad, Shenker, and Stanford, with fixed moduli. In the boundary description this saddle appears to dominate a smeared version of the connected two-point function of the black hole density of states, and suggests level repulsion in the microstate spectrum. Using these methods we further study Euclidean wormholes in pure Einstein gravity and in IIB supergravity on Euclidean AdS5× S5. We address the perturbative stability of these backgrounds and study brane nucleation instabilities in 10d supergravity. In particular, brane nucleation instabilities of the Euclidean wormholes are lifted by the analytic continuation required to obtain the Lorentzian spectral form factor from gravity. Our results indicate a factorization paradox in AdS/CFT.

scholarly journals Condiciones iniciales, comienzo y origen. Limitaciones de algunos planteamientos monistas en cosmología

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
Claudia E. Vanney
Keyword(s):  
Initial Conditions ◽  
Interdisciplinary Work ◽  
Cosmic Evolution ◽  
Palabras Clave ◽  
Cosmological Problem ◽  
Different Dimensions ◽  
M Theory ◽  
The Universe ◽  
Single Set ◽  
Origin Of The Universe

Resumen: En su último libro Hawking y Mlodinow afirman que la teoría M unifica las teorías físicas, contiene las leyes más fundamentales y responde las grandes preguntas de la humanidad. Es decir, el despliegue del universo se reduciría a un conjunto de leyes único. Este trabajo pretende: 1) Señalar algunos supuestos epistemológicos asumidos sin sufi­ciente fundamentación. 2) Proponer las nociones de condiciones iniciales, comienzo y origen, como un marco adecuado para distinguir las diferentes dimensiones del problema cosmológico. 3) Desde esta distinción enfatizar la importancia del trabajo interdisciplinar para estudiar los temas de frontera entre la ciencia y la filosofía. Palabras clave: modelos cosmológico, Steven Hawking, condiciones iniciales, evolución cósmica, origen del universo. Abstract. In their last book Hawking and Mlodinow argue that M-Theory unifies physi­cal theories, contains the most fundamental laws and answers the great questions of humanity. Namely, the unfolding of the universe would be reduced to a single set of laws. This paper seeks: 1) to identify some epistemological assumptions made with insufficient justification; 2) to propose the notion of initial conditions, beginning and origin as an ap­propriate framework to distinguish different dimensions of the cosmological problem; 3) from this distinction to emphasize the importance of interdisciplinary work to study bor­der issues between science and philosophy. Keywords: cosmological models, Steven Hawking, initial conditions, cosmic evolution, origin of the universe. Recibido: 16/02/2013 Aprobado: 18/04/2013

scholarly journals Preinflationary Dynamics of Power-Law Potential in Loop Quantum Cosmology †

Universe ◽  
2018 ◽  
Vol 4 (8) ◽  
pp. 87 ◽  
Author(s):  
M. Shahalam
Keyword(s):  
Quantum Cosmology ◽  
Initial Conditions ◽  
Big Bang ◽  
Loop Quantum Cosmology ◽  
Inflationary Universe ◽  
Slow Roll ◽  
Wide Range ◽  
The Big Bang ◽  
The Universe ◽  
Big Bang Singularity

In this article, I mainly discuss the dynamics of the pre-inflationary Universe for the potential V ( ϕ ) ∝ ϕ n with n = 5 / 3 in the context of loop quantum cosmology, in which the big bang singularity is resolved by a non-singular quantum bounce. In the case of the kinetic energy-dominated initial conditions of the scalar field at the bounce, the numerical evolution of the Universe can be split up into three regimes: bouncing, transition, and slow-roll inflation. In the bouncing regime, the numerical evolution of the scale factor does not depend on a wide range of initial values, or on the inflationary potentials. I calculate the number of e-folds in the slow-roll regime, by which observationally identified initial conditions are obtained. Additionally, I display the phase portrait for the model under consideration.

scholarly journals ASYMPTOTICALLY VANISHING COSMOLOGICAL CONSTANT IN THE MULTIVERSE

2011 ◽  
Vol 26 (18) ◽  
pp. 3107-3120 ◽  
Author(s):  
HIKARU KAWAI ◽  
TAKASHI OKADA
Keyword(s):  
Wave Function ◽  
Partition Function ◽  
Cosmological Constant ◽  
Space Time ◽  
The Other ◽  
Wkb Method ◽  
Leading Order ◽  
Lorentzian Space ◽  
Euclidean Wormholes ◽  
The Universe

We study the problem of the cosmological constant in the context of the multiverse in Lorentzian space–time, and show that the cosmological constant will vanish in the future. This sort of argument was started by Sidney Coleman in 1989, and he argued that the Euclidean wormholes make the multiverse partition function a superposition of various values of the cosmological constant Λ, which has a sharp peak at Λ = 0. However, the implication of the Euclidean analysis to our Lorentzian space–time is unclear. With this motivation, we analyze the quantum state of the multiverse in Lorentzian space–time by the WKB method, and calculate the density matrix of our universe by tracing out the other universes. Our result predicts vanishing cosmological constant. While Coleman obtained the enhancement at Λ = 0 through the action itself, in our Lorentzian analysis the similar enhancement arises from the front factor of eiS in the universe wave function, which is in the next leading order in the WKB approximation.

scholarly journals A STUDY OF KANTOWSKI–SACHS MODEL IN ASHTEKAR VARIABLES

1998 ◽  
Vol 13 (28) ◽  
pp. 4931-4937 ◽  
Author(s):  
SUBENOY CHAKRABORTY ◽  
NABAJIT CHAKRAVARTY
Keyword(s):  
Wave Function ◽  
Path Integral ◽  
Quantum Cosmology ◽  
Cosmological Term ◽  
Classical Solutions ◽  
Integral Formalism ◽  
Path Integral Formalism ◽  
Ashtekar Variables ◽  
The Universe

In this paper we study classical and quantum cosmology in Kantowski–Sachs model using Ashtekar variables. Classical solutions are obtained for the above model with a cosmological term and Hamilton–Jacobi (HJ) equations have been studied to obtain inflationary solutions. In quantum cosmology, the wave function of the Universe is obtained using path integral formalism as well as by solving the Wheeler–DeWitt (WD) equation.

Sign in / Sign up

Export Citation Format

Share Document