scholarly journals Dark Energy and the Riddle of the Cosmological Constant

2021 ◽  
Vol 4 (2) ◽  
Keyword(s):  
Dark Energy ◽  
Cosmological Constant ◽  
Large Scale ◽  
Background Radiation ◽  
Cosmic Background Radiation ◽  
Average Density ◽  
Astronomical Observations ◽  
Cosmic Background ◽  
Visible Matter ◽  
The Universe

Dark energy was created to interpret astronomical observations that the earlier standard model of cosmology could not explain. First, measurements of the pattern of cosmic background radiation revealed that the universe must be large-scale flat, corresponding to an average density greater than the "dark" and visible matter combined account for.

scholarly journals DIVISION VIII: GALAXIES AND THE UNIVERSE

2007 ◽  
Vol 3 (T26B) ◽  
pp. 179-180
Author(s):  
Francesco Bertola ◽  
Sadanori Okamura ◽  
Virginia L. Trimble ◽  
Mark Birkinshaw ◽  
Françoise Combes ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Large Scale ◽  
Local Group ◽  
Background Radiation ◽  
Cosmic Background Radiation ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Cosmic Background ◽  
Distant Galaxies ◽  
The Universe

Division VIII gathers astronomers engaged in the study of the visible and invisible matter in the Universe at large, from Local Group galaxies via distant galaxies and galaxy clusters to the large-scale structure of the Universe and the cosmic background radiation.

Anisotropy measurements and cosmological implications

1982 ◽  
Vol 307 (1497) ◽  
pp. 67-75 ◽  
Keyword(s):  
Large Scale ◽  
Background Radiation ◽  
Cosmic Background Radiation ◽  
Critical Discussion ◽  
Present Knowledge ◽  
Cosmic Background ◽  
Scale Properties ◽  
The Universe

We summarize the present knowledge of the anisotropies of the cosmic background radiation at angular scales over 1° and present recent data on the dipole and quadrupole harmonics from the Florence group. Reviewing models of cosmic structures, we describe the inferences that can be drawn from the data provided that their origin is extragalactic. We end with a critical discussion of the connection of the background anisotropies with the large-scale properties of the Universe.

BLACK HOLE SINGULARITIES, CRITICAL PHENOMENA, THE RUNAWAY UNIVERSE AND HYPERSPACE TRAVEL

2003 ◽  
Vol 12 (09) ◽  
pp. 1675-1680
Author(s):  
LIOR M. BURKO
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Energy ◽  
Radiation Field ◽  
Background Radiation ◽  
Cosmic Background Radiation ◽  
Radiation Fields ◽  
Cosmic Background ◽  
Expansion Of The Universe ◽  
The Universe

Black holes are always irradiated by the cosmic background radiation. This captured radiation field determines the physical and geometrical nature of the singularity inside the black hole. We find that non-compact radiation fields (similar to the cosmic background radiation) affect dramatically the singularity, and may determine the fate of a falling astronaut. In particular, the dark energy which accelerates the expansion of the universe determines whether the "tunnel" inside the black hole is blocked, or whether the possibility of using the black hole as a portal for hyperspace travel cannot be ruled out as yet.

scholarly journals 4. Galaxy formation

1985 ◽  
Vol 19 (1) ◽  
pp. 668-677
Author(s):  
Bernard J. T. Jones
Keyword(s):  
Galaxy Formation ◽  
Large Scale ◽  
Background Radiation ◽  
Mass Density ◽  
Cosmic Background Radiation ◽  
Cosmic Background ◽  
Scant Attention ◽  
The Subject ◽  
The Universe

This article surveys the literature from July 1981 to June 1984. It is neither possible nor desirable to refer to all papers on the subject, and accordingly only papers that are generally representative of some particular idea are explicitly mentioned. Galaxy Formation by its very nature has considerable overlap with other areas of cosmology such as the anisotropy of the cosmic background radiation, the question of the mass density of the universe, the nature of the large scale clustering, and detailed observations of galaxies. These are all topics covered by other reports to Commission 47 and the reader will therefore find only scant attention paid here to these important subjects.

Cosmology: evidence for a ‘big bang’

1994 ◽  
Vol 2 (2) ◽  
pp. 155-164
Author(s):  
Martin J. Rees
Keyword(s):  
Present State ◽  
Background Radiation ◽  
Cosmic Background Radiation ◽  
Big Bang ◽  
Fundamental Physics ◽  
Cosmic Expansion ◽  
Cosmic Background ◽  
The Universe

During the last 25 years, evidence has accumulated that our universe has evolved, over a period of 10–15 billion years, from a hot dense fireball to its present state. Telescopes can detect objects so far away that the universe had only a tenth its present age when the light we now receive set out towards us. The cosmic background radiation, and the abundances of elements such as helium and lithium, permit quantitative inferences about what the universe was like when it had been expanding for only a few seconds. The laws of physics established in the laboratory apparently suffice for interpreting all astronomical phenomena back to that time. In the initial instants of cosmic expansion, however, the particle energies and densities were so extreme that terrestrial experiments offer no firm guidance. We will not understand why the universe contains the observed ‘mix’ of matter and radiation, nor why it is expanding in the observed fashion, without further progress in fundamental physics.

Observational and astrophysical cosmology: 1980–2018

2019 ◽  
pp. 375-423
Author(s):  
Malcolm S. Longair
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cosmological Constant ◽  
Large Scale ◽  
Cosmological Parameters ◽  
Semiconductor Detectors ◽  
Empirical Knowledge ◽  
Global Geometry ◽  
The Universe ◽  
Large Scale Structure Formation

Since 1980, our empirical knowledge of the universe has advanced tremendously and precision cosmology has become a reality. These developments have been largely technology-driven, the result of increased computer power, new generations of telescopes for all wavebands, new types of semiconductor detectors, such as CCDs, and major investments by many nations in superb observing facilities. The discipline also benefitted from the influx of experimental and theoretical physicists into the cosmological arena. The accuracy and reliability of the values of the cosmological parameters has improved dramatically, many of them now being known to about 1%. The ΛCDM model provides a remarkable fit to all the observational data, demonstrating that the cosmological constant is non-zero and that the global geometry of the universe is flat. The underlying physics of galaxy and large-scale structure formation has advanced dramatically and demonstrated the key roles played by dark matter and dark energy.

DENSITY FLUCTUATIONS ON SUPER-HUBBLE SCALES

1996 ◽  
Vol 11 (19) ◽  
pp. 1531-1538 ◽  
Author(s):  
LI-ZHI FANG ◽  
YI-PENG JING
Keyword(s):  
Background Radiation ◽  
Cosmic Background Radiation ◽  
Density Fluctuations ◽  
Cosmic Background ◽  
Density Perturbations ◽  
Hubble Radius ◽  
The Universe

According to causality, the existence of density perturbations on scales larger than the present Hubble radius y = 2c/H0 is crucial to discriminate between inflation and non-inflation models of the origin of inhomogeneity of the universe. Observations of the cosmic background radiation anisotropies favor a super-Hubble suppression on scales λmax in the range 0.5–3.0y. Many of non-inflation models are consistent with such a suppression. Inflation models are certainly not in conflict with this suppression, however one important parameter, the duration of the epoch of inflation, may need to be fine tuned.

Sign in / Sign up

Export Citation Format

Share Document