scholarly journals EXACT INHOMOGENEOUS MODELS AND THE DRIFT OF LIGHT RAYS INDUCED BY NONSYMMETRIC FLOW OF THE COSMIC MEDIUM

2013 ◽  
Vol 22 (06) ◽  
pp. 1330013 ◽  
Author(s):  
ANDRZEJ KRASIŃSKI ◽  
KRZYSZTOF BOLEJKO
Keyword(s):  
Time Dependence ◽  
Real Time ◽  
Null Geodesic ◽  
Cosmological Models ◽  
Zero Drift ◽  
Inhomogeneous Models ◽  
Cosmic Medium ◽  
Light Rays ◽  
Under Construction ◽  
The Universe

After introducing the Szekeres and Lemaître–Tolman cosmological models, the real-time cosmology program is briefly mentioned. Then, a few widespread misconceptions about the cosmological models are pointed out and corrected. Investigation of null geodesic equations in the Szekeres models shows that observers in favorable positions would see galaxies drift across the sky at a rate of up to 10-6 arc s per year. Such a drift would be possible to measure using devices that are under construction; the required time of monitoring would be ≈10 years. This effect is zero in the FLRW models, so it provides a measure of inhomogeneity of the Universe. In the Szekeres models, the condition for zero drift is zero shear. But in the shearfree normal models, the condition for zero drift is that, in the comoving coordinates, the time dependence of the metric completely factors out.

scholarly journals On Gravitational Aberrations in Stellar Images

1972 ◽  
Vol 25 (6) ◽  
pp. 749
Author(s):  
MW Cook
Keyword(s):  
Cosmological Model ◽  
Null Geodesic ◽  
Average Density ◽  
Gravitational Lens ◽  
Light Sources ◽  
Spherically Symmetric ◽  
Dispersion Effect ◽  
Stellar Objects ◽  
Light Rays ◽  
The Universe

On the basis of a cosmological model which is fundamentally of the Friedmann expanding type with a spherically symmetric inhomogeneity superimposed, a study is made of three gravitational aberrations of purely relativistic origin observed in the images of stellar objects: (1) the "gravitational lens" effect, (2) a dispersion effect whereby a point source would produce a diffuse image, and (3) an 'apparent systematic motion of all light sources towards (or away from) the inhomogeneity. Admissable inhomogeneities in the model must satisfy PU ? 2�104 Mpc, where P is the ratio of the average density of matter within the inhomogeneity to the average density of the universe and U is its diameter in megaparsecs. The assumption is also made that the paths of light rays are described by the null-geodesic equations of the space-time under consideration.

Galileo Unbound

2018 ◽  
Author(s):  
David D. Nolte
Keyword(s):  
Free Fall ◽  
The Sun ◽  
Quantum Field ◽  
Many Worlds ◽  
Quantum Particles ◽  
Light Rays ◽  
History Of ◽  
And Control ◽  
The Universe ◽  
Insight Into

Galileo Unbound: A Path Across Life, The Universe and Everything traces the journey that brought us from Galileo’s law of free fall to today’s geneticists measuring evolutionary drift, entangled quantum particles moving among many worlds, and our lives as trajectories traversing a health space with thousands of dimensions. Remarkably, common themes persist that predict the evolution of species as readily as the orbits of planets or the collapse of stars into black holes. This book tells the history of spaces of expanding dimension and increasing abstraction and how they continue today to give new insight into the physics of complex systems. Galileo published the first modern law of motion, the Law of Fall, that was ideal and simple, laying the foundation upon which Newton built the first theory of dynamics. Early in the twentieth century, geometry became the cause of motion rather than the result when Einstein envisioned the fabric of space-time warped by mass and energy, forcing light rays to bend past the Sun. Possibly more radical was Feynman’s dilemma of quantum particles taking all paths at once—setting the stage for the modern fields of quantum field theory and quantum computing. Yet as concepts of motion have evolved, one thing has remained constant, the need to track ever more complex changes and to capture their essence, to find patterns in the chaos as we try to predict and control our world.

scholarly journals COSMOLOGICAL MODELS WITH VARIABLE GRAVITATIONAL AND COSMOLOGICAL CONSTANTS IN R2GRAVITY

2006 ◽  
Vol 15 (02) ◽  
pp. 189-198 ◽  
Author(s):  
P. S. DEBNATH ◽  
B. C. PAUL
Keyword(s):  
Model Building ◽  
Cosmological Models ◽  
Higher Derivative ◽  
Gravitational And Cosmological Constants ◽  
Cosmological Solutions ◽  
Cosmological Constants ◽  
The Universe ◽  
Hilbert Action

We consider the evolution of a flat Friedmann–Roberstson–Walker Universe in a higher derivative theory, including αR2terms for the Einstein–Hilbert action in the presence of variable gravitational and cosmological constants. We study the evolution of the gravitational and cosmological constants in the radiation and matter domination era of the universe. We present new cosmological solutions which are physically interesting for model building.

scholarly journals Cosmological models of the Universe without a Beginning and without a singularity

2021 ◽  
Vol 13 (3) ◽  
pp. 473-486
Author(s):  
Vladimir G. Krechet ◽  
Vadim Borisovich Oshurko ◽  
Alexey Eduardovich Kisser
Keyword(s):  
Cosmological Models ◽  
The Universe

scholarly journals Isotropization of Homogeneous Cosmological Models

1974 ◽  
Vol 63 ◽  
pp. 273-282
Author(s):  
I. D. Novikov
Keyword(s):  
Large Scale ◽  
Background Radiation ◽  
Cosmological Models ◽  
Matter Distribution ◽  
Cosmological Singularity ◽  
Universe Expand ◽  
Starting Point ◽  
Microwave Background Radiation ◽  
Friedmann Cosmological Models ◽  
The Universe

Observations primarily of the microwave background radiation show that the Universe expands isotropically with a high degree of accuracy at the present time and that the matter distribution is homogeneous on a large scale. Thus, the Friedmann cosmological models are a good approximation today for the expanding Universe. This is valid for at least some period of time in the past too. But how did the Universe expand and what was the matter distribution close to the starting point, near the cosmological singularity?

scholarly journals Astrophysics in the Laboratory—The CBM Experiment at FAIR

Particles ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 320-335
Author(s):  
Peter Senger
Keyword(s):  
Heavy Ion ◽  
High Energy ◽  
Baryonic Matter ◽  
Quantum Chromo Dynamics ◽  
Ion Collisions ◽  
Physics Program ◽  
Supernova Explosions ◽  
Under Construction ◽  
Density Equation ◽  
The Universe

The future “Facility for Antiproton and Ion Research” (FAIR) is an accelerator-based international center for fundamental and applied research, which presently is under construction in Darmstadt, Germany. An important part of the program is devoted to questions related to astrophysics, including the origin of elements in the universe and the properties of strongly interacting matter under extreme conditions, which are relevant for our understanding of the structure of neutron stars and the dynamics of supernova explosions and neutron star mergers. The Compressed Baryonic Matter (CBM) experiment at FAIR is designed to measure promising observables in high-energy heavy-ion collisions, which are expected to be sensitive to the high-density equation-of-state (EOS) of nuclear matter and to new phases of Quantum Chromo Dynamics (QCD) matter at high densities. The CBM physics program, the relevant observables and the experimental setup will be discussed.

scholarly journals Environmental express monitoring of territory and water bodies at various stages of construction and improvement

2018 ◽  
Vol 245 ◽  
pp. 11013 ◽  
Author(s):  
Nikita Myazin ◽  
Yuri Neronov ◽  
Valentin Dudkin ◽  
Vadim Davydov ◽  
Victoria Yushkova
Keyword(s):  
Real Time ◽  
Continuous Monitoring ◽  
The State ◽  
Water Bodies ◽  
Condensed Media ◽  
Effective Application ◽  
Nuclear Magnetic Spectroscopy ◽  
Under Construction ◽  
State Of The Environment ◽  
Express Monitoring

The article substantiates the need for continuous monitoring of the state of the environment both in the territories of the object under construction and in the areas of improvement works. The method of nuclear-magnetic spectroscopy is proposed, which allows carrying out ecological express monitoring of the state of condensed media (for example, water, silt, various mixtures, etc.) in real time. The results of ecological express monitoring are presented and recommendations for its more effective application are given.

scholarly journals Applying He's variational iteration method to FRW cosmology

2019 ◽  
Vol 7 (2) ◽  
pp. 39
Author(s):  
V. K.Shchigolev
Keyword(s):  
Iteration Method ◽  
System Analysis ◽  
Variational Iteration Method ◽  
Cosmological Models ◽  
Frw Cosmology ◽  
Variational Iteration ◽  
Barotropic Fluids ◽  
He’S Variational Iteration Method ◽  
High Degree ◽  
The Universe

This work is devoted to the investigation of Friedmann-Robertson-Walker (FRW) cosmological models with the help of the so-called Variational Iteration Method (VIM). For this end, we briefly recall the main equations of the cosmological models and the basic idea of VIM. In order to approbate the VIM in FRW cosmology and demonstrate the main steps in solving by this method, we consider the test example of the universe with dust for which the exact solution of the model is known. Then, a solution for the spatially flat FRW model of the universe filled with the dust and quintessence is obtained when the exact analytic solution cannot be found. A comparison of our solution with the corresponding numerical solution shows that it is of a high degree of accuracy. Moreover, the Dynamical System Analysis to the dynamics of the homogeneous and isotropic FRW universes is used as a special case of generalized Lotka–Volterra system where the competitive species are the barotropic fluids filling the Universe. With the help of VIM, we have found the iterative formulae for the density parameters of the cosmological analog of the generalized Lotka–Volterra set of equations. All solutions illustrated graphically by means of Maple software.  

scholarly journals Acceleration and Dissolution of Stars in the Antibang

1983 ◽  
Vol 104 ◽  
pp. 453-455
Author(s):  
E. R. Harrison
Keyword(s):  
Cosmological Models ◽  
Seminal Work ◽  
The Universe

If the universe is spatially closed, and the simplest cosmological models are valid approximations, then in ∼ 1011 years the universe will recollapse into an antibang. (A “bang” is explosive, whereas an “antibag” may be considered implosive.) In this note I shall add one or two details to the seminal work of Rees (1969).

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