scholarly journals Dynamic cancellation of a cosmological constant and approach to the Minkowski vacuum

2016 ◽  
Vol 31 (28) ◽  
pp. 1650160 ◽  
Author(s):  
F. R. Klinkhamer ◽  
G. E. Volovik
Keyword(s):  
Cosmological Constant ◽  
Particle Production ◽  
Planck Scale ◽  
Initial Boundary ◽  
Finite Domain ◽  
Back Reaction ◽  
Theory Approach ◽  
Dynamical Equations ◽  
Potential Term ◽  
Q Theory

The q-theory approach to the cosmological constant problem is reconsidered. The new observation is that the effective classical q-theory gets modified due to the back-reaction of quantum-mechanical particle production by spacetime curvature. Furthermore, a Planck-scale cosmological constant is added to the potential term of the action density, in order to represent the effects from zero-point energies and phase transitions. The resulting dynamical equations of a spatially-flat Friedmann–Robertson–Walker universe are then found to give a steady approach to the Minkowski vacuum, with attractor behavior for a finite domain of initial boundary conditions on the fields. The approach to the Minkowski vacuum is slow and gives rise to an inflation-type increase of the particle horizon.

scholarly journals ON VACUUM-ENERGY DECAY FROM PARTICLE PRODUCTION

2012 ◽  
Vol 27 (25) ◽  
pp. 1250150 ◽  
Author(s):  
F. R. KLINKHAMER
Keyword(s):  
Vacuum Energy ◽  
Particle Production ◽  
Energy Decay ◽  
Back Reaction ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Consistent Description ◽  
Sitter Spacetime

A simplified (but consistent) description of particle-production back-reaction effects in de Sitter spacetime is given.

scholarly journals Prediction for the cosmological constant and constraints on SUSY GUTs in resummed quantum gravity

2018 ◽  
Vol 33 (29) ◽  
pp. 1830028
Author(s):  
B. F. L. Ward
Keyword(s):  
General Theory ◽  
Quantum Gravity ◽  
Cosmological Constant ◽  
Uncertainty Principle ◽  
Planck Scale ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Heisenberg Uncertainty Principle ◽  
Heisenberg Uncertainty

Working in the context of the Planck scale cosmology formulation of Bonanno and Reuter, we use our resummed quantum gravity approach to Einstein’s general theory of relativity to estimate the value of the cosmological constant as [Formula: see text]. We show that SUSY GUT models are constrained by the closeness of this estimate to experiment. We also address various consistency checks on the calculation. In particular, we use the Heisenberg uncertainty principle to remove a large part of the remaining uncertainty in our estimate of [Formula: see text].

Particle production, back reaction and singularity avoidance

Pramana ◽  
1999 ◽  
Vol 52 (1) ◽  
pp. 1-17 ◽  
Author(s):  
A. Shaw ◽  
D. Biswas ◽  
B. Modak ◽  
S. Biswas
Keyword(s):  
Particle Production ◽  
Back Reaction ◽  
Singularity Avoidance

scholarly journals The nature of the gravitational vacuum

2019 ◽  
Vol 28 (14) ◽  
pp. 1944005
Author(s):  
Samir D. Mathur
Keyword(s):  
Black Hole ◽  
String Theory ◽  
Cosmological Constant ◽  
Mass Formula ◽  
Vacuum Energy ◽  
Planck Scale ◽  
Cosmological Constant Problem ◽  
Horizon Radius ◽  
Number Formula ◽  
Gravitational Vacuum

The vacuum must contain virtual fluctuations of black hole microstates for each mass [Formula: see text]. We observe that the expected suppression for [Formula: see text] is counteracted by the large number [Formula: see text] of such states. From string theory, we learn that these microstates are extended objects that are resistant to compression. We argue that recognizing this ‘virtual extended compression-resistant’ component of the gravitational vacuum is crucial for understanding gravitational physics. Remarkably, such virtual excitations have no significant effect for observable systems like stars, but they resolve two important problems: (a) gravitational collapse is halted outside the horizon radius, removing the information paradox, (b) spacetime acquires a ‘stiffness’ against the curving effects of vacuum energy; this ameliorates the cosmological constant problem posed by the existence of a planck scale [Formula: see text].

scholarly journals Cosmological constant, matter, cosmic inflation and coincidence

2020 ◽  
Vol 35 (15) ◽  
pp. 2050123
Author(s):  
She-Sheng Xue
Keyword(s):  
Dark Matter ◽  
Acoustic Wave ◽  
Cosmological Constant ◽  
Einstein Equation ◽  
Large Scale ◽  
Particle Production ◽  
Cosmological Term ◽  
Coincidence Problem ◽  
Cosmic Inflation ◽  
Cosmic Coincidence Problem

We present a possible understanding to the issues of cosmological constant, inflation, dark matter and coincidence problems based only on the Einstein equation and Hawking particle production. The inflation appears and results agree to observations. The CMB large-scale anomaly can be explained and the dark-matter acoustic wave is speculated. The entropy and reheating are discussed. The cosmological term [Formula: see text] tracks down the matter [Formula: see text] until the radiation-matter equilibrium, then slowly varies, thus the cosmic coincidence problem can be avoided. The relation between [Formula: see text] and [Formula: see text] is shown and can be examined at large redshifts.

The q‐Theory Approach to Understanding the Accrual Anomaly

2010 ◽  
Vol 48 (1) ◽  
pp. 177-223 ◽  
Author(s):  
JIN (GINGER) WU ◽  
LU ZHANG ◽  
X. FRANK ZHANG
Keyword(s):  
Theory Approach ◽  
Accrual Anomaly ◽  
Q Theory

scholarly journals Einstein–Heisenberg consistency condition interplay with cosmological constant prediction in resummed quantum gravity

2015 ◽  
Vol 30 (38) ◽  
pp. 1550206 ◽  
Author(s):  
B. F. L. Ward
Keyword(s):  
Quantum Gravity ◽  
Cosmological Constant ◽  
Promising Result ◽  
Consistency Condition ◽  
Planck Scale ◽  
Theory Of Relativity ◽  
Heisenberg Uncertainty Principle ◽  
Recent Success ◽  
Heisenberg Uncertainty ◽  
Frw Model

We argue that our recent success in using our resummed quantum gravity (RQG) approach to Einstein’s general theory of relativity, in the context of the Planck scale cosmology formulation of Bonanno and Reuter, to estimate the value of the cosmological constant [Formula: see text] supports the use of quantum mechanical consistency requirements to constrain the main uncertainty in that very promising result. This main uncertainty, which is due to the uncertainty in the value of the time [Formula: see text] at which the transition from the Planck scale cosmology to the FRW model occurs, is shown to be reduced, by requiring consistency between the Heisenberg uncertainty principle and the known properties of the solutions of Einstein’s equations, from four orders of magnitude to the level of a factor of [Formula: see text]. This lends more credibility to the overall RQG approach itself, in general, and to our estimate of [Formula: see text] in particular.

scholarly journals Cosmological constant in SUGRA models with Planck scale SUSY breaking and degenerate vacua

2014 ◽  
Vol 737 ◽  
pp. 167-171 ◽  
Author(s):  
C.D. Froggatt ◽  
R. Nevzorov ◽  
H.B. Nielsen ◽  
A.W. Thomas
Keyword(s):  
Cosmological Constant ◽  
Planck Scale ◽  
Susy Breaking

scholarly journals Degenerate Bogdanov–Takens bifurcations in a bulk viscous cosmology

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Asmaa Abdel Azim ◽  
Adel Awad ◽  
E. I. Lashin
Keyword(s):  
Cosmological Constant ◽  
Phase Portrait ◽  
State Parameter ◽  
Viscosity Coefficient ◽  
Observational Cosmology ◽  
Finite Domain ◽  
Dynamical System Theory ◽  
Stability Properties ◽  
Bulk Viscous Fluid ◽  
Bulk Viscous

AbstractUsing the dynamical system theory we show that the Friedmann–Robertson–Walker (FRW) cosmological model with bulk viscous fluid in the presence of cosmological constant is equivalent to a degenerate two dimensional Bogdanov–Takens normal form. The equation of state parameter, $$\omega $$ ω , the bulk viscosity coefficient, $$\xi $$ ξ , and the cosmological constant, $$\Lambda $$ Λ , define the necessary parameters for unfolding the degenerate Bogdanov-Takens system. The fixed points of the system are discussed together with the variation of their stability properties upon changing the relevant parameters $$\omega , \Lambda $$ ω , Λ and $$\xi $$ ξ . The variation of the stability properties are visualized by the appropriate bifurcation diagrams. Phase portrait for finite domain and global phase portrait are displayed and the issue of the structural stability is discussed. Typical issues such as late acceleration or inflation that can be induced by viscosity and could have relevance to observational cosmology are also discussed.

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