The Age of the Universe and the Cosmological Constant Determined from Cosmic Microwave Background Anisotropy Measurements

2001 ◽  
Vol 563 (2) ◽  
pp. L95-L98 ◽  
Author(s):  
Lloyd Knox ◽  
Nelson Christensen ◽  
Constantinos Skordis
Keyword(s):  
Cosmic Microwave Background ◽  
Cosmological Constant ◽  
Microwave Background ◽  
Cosmic Microwave Background Anisotropy ◽  
Age Of The Universe ◽  
The Universe

scholarly journals Cosmic Microwave Background Anisotropy at Degree Angular Scales and the Thermal History of the Universe

1997 ◽  
Vol 480 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Paolo de Bernardis ◽  
Amedeo Balbi ◽  
Giancarlo De Gasperis ◽  
Alessandro Melchiorri ◽  
Nicola Vittorio
Keyword(s):  
Cosmic Microwave Background ◽  
Thermal History ◽  
Microwave Background ◽  
Cosmic Microwave Background Anisotropy ◽  
History Of ◽  
The Universe

The TopHat Cosmic Microwave Background Anisotropy Experiment

2005 ◽  
Vol 201 ◽  
pp. 65-70
Author(s):  
Robert F. Silverberg ◽  
Keyword(s):  
Cosmic Microwave Background ◽  
Large Scale ◽  
Background Radiation ◽  
High Sensitivity ◽  
Microwave Background ◽  
Long Duration ◽  
Cosmic Microwave Background Anisotropy ◽  
Microwave Background Radiation ◽  
The Universe ◽  
Large Scale Structure Formation

We have developed a balloon-borne experiment to measure the Cosmic Microwave Background Radiation anisotropy on angular scales from ˜50° down to ˜20′. The instrument observes at frequencies between 150 and 690 GHz and will be flown on an Antarctic circumpolar long duration flight. To greatly improve the experiment performance, the front-end of the experiment is mounted on the top of the balloon. With high sensitivity, broad sky coverage, and well-characterized systematic errors, the results of this experiment can be used to strongly constrain cosmological models and probe the early stages of large-scale structure formation in the Universe.

scholarly journals The habitable epoch of the early Universe

2014 ◽  
Vol 13 (4) ◽  
pp. 337-339 ◽  
Author(s):  
Abraham Loeb
Keyword(s):  
Cosmic Microwave Background ◽  
Cosmological Constant ◽  
Water Chemistry ◽  
Early Universe ◽  
Liquid Water ◽  
Matter Density ◽  
Microwave Background ◽  
Star Forming ◽  
Rocky Planets ◽  
The Universe

AbstractIn the redshift range 100≲(1+z)≲137, the cosmic microwave background (CMB) had a temperature of 273–373 K (0–100°C), allowing early rocky planets (if any existed) to have liquid water chemistry on their surface and be habitable, irrespective of their distance from a star. In the standard ΛCDM cosmology, the first star-forming halos within our Hubble volume started collapsing at these redshifts, allowing the chemistry of life to possibly begin when the Universe was merely 10–17 million years old. The possibility of life starting when the average matter density was a million times bigger than it is today is not in agreement with the anthropic explanation for the low value of the cosmological constant.

THE CASE FOR A POSITIVE COSMOLOGICAL Λ-TERM

2000 ◽  
Vol 09 (04) ◽  
pp. 373-443 ◽  
Author(s):  
VARUN SAHNI ◽  
ALEXEI STAROBINSKY
Keyword(s):  
Cosmological Constant ◽  
Gravitational Lensing ◽  
High Redshift ◽  
Scalar Fields ◽  
Accelerating Universe ◽  
Microwave Background ◽  
Present Epoch ◽  
Polarization Effects ◽  
Age Of The Universe ◽  
The Universe

Recent observations of Type 1a supernovae indicating an accelerating universe have once more drawn attention to the possible existence, at the present epoch, of a small positive Λ-term (cosmological constant). In this paper we review both observational and theoretical aspects of a small cosmological Λ-term. We discuss the current observational situation focusing on cosmological tests of Λ including the age of the universe, high redshift supernovae, gravitational lensing, galaxy clustering and the cosmic microwave background. We also review the theoretical debate surrounding Λ: the generation of Λ in models with spontaneous symmetry breaking and through quantum vacuum polarization effects — mechanisms which are known to give rise to a large value of Λ hence leading to the "cosmological constant problem." More recent attempts to generate a small cosmological constant at the present epoch using either field theoretic techniques, or by modelling a dynamical Λ-term by scalar fields are also extensively discussed. Anthropic arguments favouring a small Λ-term are briefly reviewed. A comprehensive bibliography of recent work on Λ is provided.

COSMOLOGY CONFRONTS THE COSMIC MICROWAVE BACKGROUND

1995 ◽  
Vol 10 (08) ◽  
pp. 1091-1124 ◽  
Author(s):  
PAUL J. STEINHARDT
Keyword(s):  
Cosmic Microwave Background ◽  
Initial Conditions ◽  
Experimental Tests ◽  
Inflationary Model ◽  
Microwave Background ◽  
Cosmic Microwave Background Anisotropy ◽  
Physical Laws ◽  
The Universe ◽  
Fundamental Physical ◽  
Physical Principles

Observational tests during the next decade may determine if the evolution of the Universe can be understood from fundamental physical principles, or if special initial conditions, coincidences, and new, untestable physical laws must be invoked. The inflationary model of the Universe is an important example of a predictive cosmological theory based on physical principles. In this article, we discuss the distinctive fingerprint that inflation leaves on the cosmic microwave background anisotropy. We then suggest a series of five milestone experimental tests of the microwave background which could determine the validity of the inflationary hypothesis within the next decade.

scholarly journals Uniformity of cosmic microwave background as a non-inflationary geometrical effect

2015 ◽  
Vol 30 (35) ◽  
pp. 1530026
Author(s):  
Branislav Vlahovic ◽  
Maxim Eingorn ◽  
Cosmin Ilie
Keyword(s):  
Cosmological Model ◽  
Cosmic Microwave Background ◽  
Light Propagation ◽  
Space Region ◽  
Microwave Background ◽  
Planck Data ◽  
Spatial Geometry ◽  
Geometrical Effect ◽  
Age Of The Universe ◽  
The Universe

The conventional [Formula: see text]CDM cosmological model supplemented by the inflation concept describes the Universe very well. However, there are still a few concerns: new Planck data impose constraints on the shape of the inflaton potential, which exclude a lot of inflationary models; dark matter is not detected directly, and dark energy is not understood theoretically on a satisfactory level. In this brief sketch, we investigate an alternative cosmological model with spherical spatial geometry and an additional perfect fluid with the constant parameter [Formula: see text] in the linear equation of state. It is demonstrated explicitly that in the framework of such a model it is possible to satisfy the supernovae data at the same level of accuracy as within the [Formula: see text]CDM model and at the same time suppose that the observed cosmic microwave background (CMB) radiation originates from a very limited space region. This is ensured by introducing an additional condition of light propagation between the antipodal points during the age of the Universe. Consequently, the CMB uniformity can be explained without the inflation scenario. The corresponding drawbacks of the model with respect to its comparison with the CMB data are also discussed.

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