scholarly journals The Solution of the Cosmological Constant Problem: The Cosmological Constant Exponential Decrease in the Super-Early Universe

Universe ◽  
2020 ◽  
Vol 6 (12) ◽  
pp. 230
Author(s):  
Ol’ga Babourova ◽  
Boris Frolov
Keyword(s):  
Cosmological Constant ◽  
Big Bang ◽  
Cosmological Constant Problem ◽  
Scale Invariant ◽  
Weyl Space ◽  
Effective Cosmological Constant ◽  
Exponential Decrease ◽  
The Big Bang ◽  
Modern Era ◽  
Gauge Theory Of Gravity

The stage of a super-early (primordial) scale-invariant Universe is considered on the basis of the Poincaré–Weyl gauge theory of gravity in a Cartan–Weyl space-time. An approximate solution has been found that demonstrates an inflationary behavior of the scale factor and, at the same time, a sharp exponential decrease in the effective cosmological constant from a huge value at the beginning of the Big Bang to an extremely small (but not zero) value in the modern era, which solves the well-known “cosmological constant problem.”

scholarly journals The Solution of the Cosmological Constant Problem: The Cosmological Constant Exponential Decrease in the Super-Early Universe

2020 ◽  
Author(s):  
Ol'ga Babourova ◽  
Boris Frolov
Keyword(s):  
Cosmological Constant ◽  
Big Bang ◽  
Cosmological Constant Problem ◽  
Scale Invariant ◽  
Weyl Space ◽  
Effective Cosmological Constant ◽  
Exponential Decrease ◽  
The Big Bang ◽  
Modern Era ◽  
Gauge Theory Of Gravity

The stage of a super-early scale-invariant Universe is considered on the basis of the Poincaré–Weyl gauge theory of gravity in a Cartan–Weyl space-time. An approximate solution has been found that demonstrates an inflationary behavior of the scale factor and, at the same time, a sharp exponential decrease in the effective cosmological constant from a huge value at the beginning of the Big Bang to an extremely small (but not zero) value in the modern era, which solves the well-known “cosmological constant problem”.

scholarly journals Decrease of the effective cosmological constant in the Poincare gauge theory of gravity with a scalar field

2021 ◽  
Vol 2081 (1) ◽  
pp. 012015
Author(s):  
O V Babourova ◽  
B N Frolov
Keyword(s):  
Gauge Theory ◽  
Scalar Field ◽  
Cosmological Constant ◽  
Big Bang ◽  
Cosmological Constant Problem ◽  
Effective Cosmological Constant ◽  
Theory Of Gravity ◽  
The Big Bang ◽  
Modern Era ◽  
Gauge Theory Of Gravity

Abstract Cosmological consequences of the Poincare gauge theory of gravity are considered. An effective cosmological constant depending from the Dirac scalar field is introduced. It is proved that at the super-early Universe, the effective cosmological constant decreases exponentially from a huge value at the Big Bang to its extremely small value in the modern era, while the scale factor sharply increases and demonstrates inflationary behavior. This fact solves the well-known “cosmological constant problem” also in the Poincare gauge theory of gravity.

scholarly journals Measurement and Implications of the Cosmic Microwave Background Spectrum

1996 ◽  
Vol 168 ◽  
pp. 17-29
Author(s):  
John C. Mather
Keyword(s):  
Background Radiation ◽  
Far Infrared ◽  
Big Bang ◽  
Scale Invariant ◽  
Background Spectrum ◽  
Nasa Goddard Space ◽  
Wide Range ◽  
Infrared Background ◽  
Microwave Radiometers ◽  
The Big Bang

The Cosmic Background Explorer (COBE) was developed by NASA Goddard Space Flight Center to measure the diffuse infrared and microwave radiation from the early universe. It also measured emission from nearby sources such as the stars, dust, molecules, atoms, ions, and electrons in the Milky Way, and dust and comets in the Solar System. It was launched 18 November 1989 on a Delta rocket, carrying one microwave instrument and two cryogenically cooled infrared instruments. The Far Infrared Absolute Spectrophotometer (FIRAS) mapped the sky at wavelengths from 0.01 to 1 cm, and compared the CMBR to a precise blackbody. The spectrum of the CMBR differs from a blackbody by less than 0.03%. The Differential Microwave Radiometers (DMR) measured the fluctuations in the CMBR originating in the Big Bang, with a total amplitude of 11 parts per million on a 10° scale. These fluctuations are consistent with scale-invariant primordial fluctuations. The Diffuse Infrared Background Experiment (DIRBE) spanned the wavelength range from 1.2 to 240 μm and mapped the sky at a wide range of solar elongation angles to distinguish foreground sources from a possible extragalactic Cosmic Infrared Background Radiation (CIBR). In this paper we summarize the COBE mission and describe the results from the FIRAS instrument. The results from the DMR and DIRBE were described by Smoot and Hauser at this Symposium.

scholarly journals Big bounce with finite-time singularity: The F(R) gravity description

2017 ◽  
Vol 26 (08) ◽  
pp. 1750085 ◽  
Author(s):  
S. D. Odintsov ◽  
V. K. Oikonomou
Keyword(s):  
Big Bang ◽  
Einstein Frame ◽  
Jordan Frame ◽  
Cosmological Perturbations ◽  
Scale Invariant ◽  
Type Iv ◽  
Big Rip ◽  
Cosmological Scenario ◽  
The Big Bang ◽  
Big Bounce

An alternative to the Big Bang cosmologies is obtained by the Big Bounce cosmologies. In this paper, we study a bounce cosmology with a Type IV singularity occurring at the bouncing point in the context of [Formula: see text] modified gravity. We investigate the evolution of the Hubble radius and we examine the issue of primordial cosmological perturbations in detail. As we demonstrate, for the singular bounce, the primordial perturbations originating from the cosmological era near the bounce do not produce a scale-invariant spectrum and also the short wavelength modes after these exit the horizon, do not freeze, but grow linearly with time. After presenting the cosmological perturbations study, we discuss the viability of the singular bounce model, and our results indicate that the singular bounce must be combined with another cosmological scenario, or should be modified appropriately, in order that it leads to a viable cosmology. The study of the slow-roll parameters leads to the same result indicating that the singular bounce theory is unstable at the singularity point for certain values of the parameters. We also conformally transform the Jordan frame singular bounce, and as we demonstrate, the Einstein frame metric leads to a Big Rip singularity. Therefore, the Type IV singularity in the Jordan frame becomes a Big Rip singularity in the Einstein frame. Finally, we briefly study a generalized singular cosmological model, which contains two Type IV singularities, with quite appealing features.

scholarly journals Big-Bang nucleosynthesis: Constraints on nuclear reaction rates, neutrino degeneracy, inhomogeneous and Brans–Dicke models

2017 ◽  
Vol 26 (08) ◽  
pp. 1741003 ◽  
Author(s):  
Riou Nakamura ◽  
Masa-Aki Hashimoto ◽  
Ryotaro Ichimasa ◽  
Kenzo Arai
Keyword(s):  
Cosmological Constant ◽  
Nuclear Reaction ◽  
Recent Progress ◽  
Reaction Rates ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Friedmann Model ◽  
Theory Of Gravitation ◽  
The Big Bang

We review the recent progress in the Big-Bang nucleosynthesis which includes the standard and nonstandard theory of cosmology, effects of neutrino degeneracy, and inhomogeneous nucleosynthesis within the framework of a Friedmann model. As for a nonstandard theory of gravitation, we adopt a Brans–Dicke theory which incorporates a cosmological constant. We constrain various parameters associated with each subject.

scholarly journals Quantization of time and the big bang via scale-invariant loop gravity

2020 ◽  
Vol 800 ◽  
pp. 135106
Author(s):  
Charles H.-T. Wang ◽  
Marcin Stankiewicz
Keyword(s):  
Big Bang ◽  
Scale Invariant ◽  
The Big Bang ◽  
Loop Gravity

COSMOLOGY WITH DECAYING DARK ENERGY AND COSMOLOGICAL "CONSTANT"

2008 ◽  
Vol 17 (13n14) ◽  
pp. 2527-2533 ◽  
Author(s):  
P. S. WESSON ◽  
B. MASHHOON ◽  
J. M. OVERDUIN
Keyword(s):  
Dark Energy ◽  
Cosmological Constant ◽  
Dimensional Space ◽  
Big Bang ◽  
Higher Dimensional ◽  
The Big Bang ◽  
Good Agreement

We outline an improved cosmology which uses a higher-dimensional space of the type implied by unification, where the cosmological "constant" decays from an unbounded value at the big bang to an acceptable value today. This model leads to a better understanding of inflation and is in good agreement with observations of galaxies.

scholarly journals Nuclear Constraints on the Age of the Universe

1983 ◽  
Vol 6 ◽  
pp. 241-253 ◽  
Author(s):  
David N. Schramm
Keyword(s):  
Cosmological Constant ◽  
Nuclear Physics ◽  
Big Bang ◽  
Distance Scale ◽  
The Other ◽  
Single Measurement ◽  
Age Of The Universe ◽  
The Big Bang ◽  
The Universe ◽  
Fair Degree

In this paper a review will be made of how one can use nuclear physics to put rather stringent limits on the age of the universe and thus the cosmic distance scale. As the other papers in this session have demonstrated there is some disagreement on the distance scale and thus the limits on the age of the universe (if the cosmological constant Λ = 0.) However, the disagreement is only over the last factor of 2, the basic timescale seems to really be remarkably well agreed upon. The universe is billions of years old - not thousands, not quintillions but billions of years. That our universe has a finite age is philosophically intriguing. That we can estimate that age to a fair degree of accuracy is truly impressive.No single measurement of the time since the Big Bang gives a specific, unambiguous age. Fortunately, we have at our disposal several methods that together fix the age with surprising precision.

A holographic big bang?

2015 ◽  
Vol 24 (12) ◽  
pp. 1544029
Author(s):  
N. Afshordi ◽  
R. B. Mann ◽  
R. Pourhasan
Keyword(s):  
Cosmological Model ◽  
Big Bang ◽  
Initial Singularity ◽  
Scale Invariant ◽  
The Big Bang ◽  
The Universe ◽  
Important Test

We present a cosmological model in which the Universe emerges out of the collapse of a five-dimensional (5D) star as a spherical three-brane. The initial singularity of the big bang becomes hidden behind a causal horizon. Near scale-invariant primordial curvature perturbations can be induced on the brane via a thermal atmosphere that is in equilibrium with the brane, circumventing the need for a separate inflationary process and providing an important test of the model.

scholarly journals Gravity as the breakdown of conformal invariance

2015 ◽  
Vol 24 (12) ◽  
pp. 1543002 ◽  
Author(s):  
Giovanni Amelino-Camelia ◽  
Michele Arzano ◽  
Giulia Gubitosi ◽  
João Magueijo
Keyword(s):  
Gravity Waves ◽  
Conformal Invariance ◽  
Scale Invariance ◽  
Big Bang ◽  
Two Dimensional ◽  
Top Down ◽  
Scale Invariant ◽  
Primordial Power Spectrum ◽  
The Big Bang ◽  
The Universe

In this paper, we propose that at the beginning of the universe gravity existed in a limbo either because it was switched off or because it was only conformally coupled to all particles. This picture can be reverse-engineered from the requirement that the cosmological perturbations be (nearly) scale-invariant without the need for inflation. It also finds support in recent results in quantum gravity suggesting that spacetime becomes two-dimensional at super-Planckian energies. We advocate a novel top-down approach to cosmology based on the idea that gravity and the Big Bang Universe are relics from the mechanism responsible for breaking the fundamental conformal invariance. Such a mechanism should leave clear signatures in departures from scale-invariance in the primordial power spectrum and the level of gravity waves generated.

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