scholarly journals The Standard Cosmological Model: Basic Geometric and Kinematic Features

2019 ◽  
Author(s):  
Dmitrij Nagirner ◽  
Svetlana Jorstad
Keyword(s):  
Cosmological Model ◽  
Uniform Space ◽  
Accelerating Expansion ◽  
History Of ◽  
Standard Cosmological Model ◽  
The Times ◽  
Effects Of Radiation ◽  
Late Stages ◽  
The Universe ◽  
Kinematic Properties

We present a brief history of the construction of models of the universe, followed by calculations of quantitative characteristics of basic geometric and kinematic properties of the Standard Cosmological Model ($\Lambda$CDM). Using the Friedmann equations of uniform space, we derive equations characterizing a $\Lambda$CDM model that describes a universe corresponding to current observational data. The equations take into account the effects of radiation and ultra-relativistic neutrinos. It is shown that the universe at very early and late stages can be described to sufficient accuracy by simple formulas. Certain important moments of cosmic evolution are determined: the times when densities of the gravitational components of the universe become equal, when they contribute equally to the gravitational force, when the accelerating expansion of space begins, and several others. The dependences of different distances on redshift and the scale factor of space are derived. The distance to the sphere that expands with the speed of light (the Hubble distance), and its current and future acceleration, are found. Concepts of a horizon, second inflation, and second horizon are discussed. We consider the remote future of the universe and the opportunity, in principle, of connection with extraterrestrial civilizations.

scholarly journals O UNIVERSO VIVO

2012 ◽  
Vol 19 (1.2) ◽  
Author(s):  
Francisco César de Sá Barreto ◽  
Luiz Paulo Ribeiro Vaz ◽  
Gabriel Armando Pellegatti Franco
Keyword(s):  
Cosmological Model ◽  
Chemical Elements ◽  
Big Bang ◽  
Living System ◽  
Irreversible Processes ◽  
Thermodynamics Of Irreversible Processes ◽  
Protons And Neutrons ◽  
Standard Cosmological Model ◽  
The Big Bang ◽  
The Universe

The standard cosmological model suggests that after the “Big Bang”, 14 billion of years ago, the universe entered a period of expansion and cooling. In the first one millionth of a second appear quarks, glúons, electrons and neutrinos, followed by the appearance of protons and neutrons. In this paper, we describe the “cosmic battle” between gravitation and energy, responsible for the lighter chemical elements and the formation of the stars. We describe the thermodynamics of irreversible processes of systems which are far away from equilibrium, a route that is followed by the universe, seen as a living system.

scholarly journals The Perturbation of Material Density in f(R) Modified Gravity of Polynormal Exponential Form

10.29007/xqpk ◽  
2020 ◽  
Author(s):  
Van On Vo
Keyword(s):  
Cosmological Model ◽  
Modified Gravity ◽  
Linear Perturbation ◽  
Exponential Form ◽  
Material Density ◽  
Gravitational Model ◽  
Standard Cosmological Model ◽  
The Difference ◽  
Evolutionary Aspects ◽  
The Universe

In this paper, we investigate the linear perturbation of the material density of the universe in f(R) modified gravity of polynomial exponential form on the scale of distance below the cosmic horizon (sub-horizon). The results show that the model for the evolutionary aspects of the universe is slightly different from that in the standard cosmological model of ΛCDM. They can be used to show the difference between this modified gravitational model with the standard cosmological model of ΛCMD and other cosmological models. We also investigate the ration Ψ/ Φ and Geff / GN in the model and show that they are within allowable limits of experiments.

Emerson and the Virtues

1985 ◽  
Vol 19 ◽  
pp. 135-152
Author(s):  
Ellen Kappy Suckiel
Keyword(s):  
Nineteenth Century ◽  
Human Activities ◽  
Good Reason ◽  
Human Condition ◽  
Human Beings ◽  
History Of ◽  
The Times ◽  
The Universe ◽  
American Thought

Ralph Waldo Emerson, whose life spanned most of the nineteenth century, is widely regarded as one of the greatest sages in the history of American thought. Among educated American citizenry, Emerson is probably the most commonly read indigenous philosopher—and for good reason. Emerson presents a vision of human beings and their place in the universe which gives meaning and stature to the human condition. His profound, even religious, optimism, gives structure and import to even the smallest and apparently least significant of human activities. The inspirational quality of Emerson's, prose, his willingness to travel far and wide to lecture, his ability to help people transcend the difficulties of the times, all led to his very great national as well as international significance.

Emerson and the Virtues

1985 ◽  
Vol 19 ◽  
pp. 135-152
Author(s):  
Ellen Kappy Suckiel
Keyword(s):  
Nineteenth Century ◽  
Human Activities ◽  
Good Reason ◽  
Human Condition ◽  
Human Beings ◽  
History Of ◽  
The Times ◽  
The Universe ◽  
American Thought

Ralph Waldo Emerson, whose life spanned most of the nineteenth century, is widely regarded as one of the greatest sages in the history of American thought. Among educated American citizenry, Emerson is probably the most commonly read indigenous philosopher—and for good reason. Emerson presents a vision of human beings and their place in the universe which gives meaning and stature to the human condition. His profound, even religious, optimism, gives structure and import to even the smallest and apparently least significant of human activities. The inspirational quality of Emerson's, prose, his willingness to travel far and wide to lecture, his ability to help people transcend the difficulties of the times, all led to his very great national as well as international significance.

Gravity, stability and cosmological models

2017 ◽  
Vol 26 (12) ◽  
pp. 1743026
Author(s):  
Asher Yahalom
Keyword(s):  
Stability Analysis ◽  
Cosmological Model ◽  
Cosmological Constant ◽  
Energy Momentum Tensor ◽  
Momentum Tensor ◽  
Lorentzian Metric ◽  
Standard Cosmological Model ◽  
Flat Spacetimes ◽  
Stable Solutions ◽  
The Universe

Stability analysis plays a major rule in our understanding of nature. For example it was shown that among empty flat spacetimes only those with a Lorentzian metric are stable [A. Yahalom, Found Phys. 38 (2008) 489–497; Int. J. Mod. Phys. D 18(4) (2009) 2155–2158]. However, the universe is not empty and the energy momentum tensor is metric dependent an thus effects stability. In this essay we concentrate on simple perturbations of the standard cosmological model with and without cosmological constant which is based on a uniform mass distribution. The results suggest that while Euclidean, open or closed section models are valid solutions, the choice of stable solutions is limited. In particular, the popular Lambda-CDM model is unstable.

scholarly journals Cosmological evolution with interaction between dark energy and dark matter

2015 ◽  
Vol 24 (03) ◽  
pp. 1530007 ◽  
Author(s):  
Yuri L. Bolotin ◽  
Alexander Kostenko ◽  
Oleg A. Lemets ◽  
Danylo A. Yerokhin
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cosmological Model ◽  
Holographic Dark Energy ◽  
Main Task ◽  
Nonlinear Interactions ◽  
Dark Sector ◽  
Standard Cosmological Model ◽  
Linear And Nonlinear ◽  
The Universe

In this review we consider in detail different theoretical topics associated with interaction in the dark sector. We study linear and nonlinear interactions which depend on the dark matter and dark energy densities. We consider a number of different models (including the holographic dark energy and dark energy in a fractal universe), with interacting dark energy and dark matter, have done a thorough analysis of these models. The main task of this review was not only to give an idea about the modern set of different models of dark energy, but to show how much can be diverse dynamics of the universe in these models. We find that the dynamics of a universe that contains interaction in the dark sector can differ significantly from the Standard Cosmological Model.

scholarly journals HARMONY, CICERO`S PRINCIPLE OF GOVERNING

2020 ◽  
Vol 4 (1) ◽  
pp. 11-16
Author(s):  
Ion Cordoneanu ◽  
Keyword(s):  
Body Politic ◽  
Byzantine Empire ◽  
World Culture ◽  
Governing Principle ◽  
Political Principle ◽  
History Of ◽  
The Republic ◽  
The Times ◽  
The Universe ◽  
Foundation Stone

Harmony is one of the concepts that permeate the history of human creation in varied fields: philosophy, arts, music, science, economics, politics, etc. It is a preoccupation of the Pythagorean, of Plato and Aristotle, and a governing principle theorised during the times of the Byzantine Empire. However, in Cicero’s political thinking, harmony is the foundation stone of the organisation and functioning of the republic as body politic, a political principle which reflects the principle of the entire universe. Somnium Scipionis (The Dream of Scipio), an allegory on the harmony of the universe, is the closing part of the treatise De re publica, by which Cicero, inspired by Plato and synthetizing stoic, epicurean and neoplatonic ideas, bestows his political testament upon world culture and advocates the cultivation of virtue.

scholarly journals EVOLUTION OF DISTRIBUTION FUNCTION FOR COSMOLOGICAL NEUTRINO

2013 ◽  
Vol 23 ◽  
pp. 379-385 ◽  
Author(s):  
HYUNG WON LEE ◽  
KYOUNG YEE KIM ◽  
REMO RUFFINI
Keyword(s):  
Distribution Function ◽  
Cosmological Model ◽  
Cosmological Models ◽  
Standard Cosmological Model ◽  
Degenerate Neutrino ◽  
The Universe ◽  
Quintessence Model

Recent experimental evidences show that the universe is accelerating. There are many modified cosmological models to explain this accelerating phase including ΛCDM, quintessence model, Brans-Dicke, f(R) gravity, and others. In this talk we want to check the possibility of explaining the current accelerating phase using standard cosmological model with degenerate neutrino. We will study the evolution of distribution function of degenerate neutrinos with standard Friedmann-Lemaître-Roberston-Walker(FLRW) background.

scholarly journals A hybrid model of viscous and Chaplygin gas to tackle the Universe acceleration

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
A. Hernández-Almada ◽  
Miguel A. García-Aspeitia ◽  
M. A. Rodríguez-Meza ◽  
V. Motta
Keyword(s):  
Cosmological Model ◽  
Hybrid Model ◽  
Hubble Constant ◽  
Chaplygin Gas ◽  
Joint Analysis ◽  
Acoustic Oscillations ◽  
Generalized Chaplygin Gas ◽  
Om Diagnostic ◽  
Standard Cosmological Model ◽  
The Universe

AbstractMotivated by two seminal models proposed to explain the Universe acceleration, this paper is devoted to study a hybrid model which is constructed through a generalized Chaplygin gas with the addition of a bulk viscosity. We call the model a viscous generalized Chaplygin gas (VGCG) and its free parameters are constrained through several cosmological data like the Observational Hubble Parameter, Type Ia Supernovae, Baryon Acoustic Oscillations, Strong Lensing Systems, HII Galaxies and using Joint Bayesian analysis. In addition, we implement a Om-diagnostic to analyze the VGCC dynamics and its difference with the standard cosmological model. The hybrid model shows important differences when compared with the standard cosmological model. Finally, based on our Joint analysis we find that the VGCG could be an interesting candidate to alleviate the well-known Hubble constant tension.

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