scholarly journals Hubble expansion and structure formation in time varying vacuum models

2009 ◽  
Vol 80 (8) ◽  
Author(s):  
Spyros Basilakos ◽  
Manolis Plionis ◽  
Joan Solà
Keyword(s):  
Structure Formation ◽  
Time Varying ◽  
Hubble Expansion

scholarly journals Time Varying Cosmological Constant and Its Implications for Structure Formation

2021 ◽  
Author(s):  
Louise Rebecca ◽  
C Sivaram ◽  
Arun Kenath
Keyword(s):  
Cosmological Constant ◽  
Structure Formation ◽  
Large Scale ◽  
Constant Term ◽  
Time Varying ◽  
True Nature ◽  
Large Scale Structures ◽  
Set Constraints ◽  
Scale Structures ◽  
The Universe

Although the presence of dark energy is well established from various observations, its true nature is still not well understood. The cosmological constant term seems to be the preferred candidate. In earlier work we had a constant cosmological constant term to limit the sizes of large-scale structures at lower redshifts. In this work, we extend this to large scale structures at higher redshifts. Here we invoke a time varying cosmological constant to set constraints on sizes of galaxies at high redshifts and see that they are consistent with their observed sizes. The time-varying cosmological constant also provides a possible solution to the puzzle of structure formation of large disk galaxies (like the Wolfe disk) observed at very early stages of the Universe. Future observations of galaxies at even higher redshifts could support our approach.

scholarly journals Structure Formation After the Era of Cosmic Matter Recombination

2021 ◽  
Vol 4 (3) ◽  
Keyword(s):  
Structure Formation ◽  
Acoustic Oscillation ◽  
Big Bang ◽  
Neutral Gas ◽  
Hubble Expansion ◽  
Oscillation Modes ◽  
Expansion Of The Universe ◽  
Increasing Temperature ◽  
The Big Bang ◽  
The Universe

In an aforegoing paper (Fahr and Heyl, 2021) we have studied in physical details the event of cosmic matter recombination expected at about 400000 years after the Big Bang at cosmic photon redshifts of about zr =1000. It turned out there, that photons taken as surely cooling by permanent increase of their cosmic redshifts, while electrons and protons partly are cooled by Thomson scatter processes with photons, but partly are heated due to the Hubble expansion of the universe. It can be shown, however, that in this cosmic epoch the cooling of electrons and protons is much more effective than the heating, and that a recombination of cosmic matter to neutral H-atoms thus is unavoidable. We then show, however, that the neutral gas atoms do not couple anymore to the cosmic CMB photon field, but instead are subject only to the Hubble migration in velocity space and thus become heated again. The question then poses itself, how cosmic structure formation in a gas with decreasing density and increasing temperature should have been able to take place. Where did the galaxies and clusters of galaxies come from? Looking into the unstable, self-gravitating acoustic oscillation modes we find the answer at what cosmic times which magnitudes of self gravitating critical masses can have been produced that could have sustained till the present times.

scholarly journals Hubble expansion and structure formation in the ``running FLRW model'' of the cosmic evolution

2011 ◽  
Vol 2011 (08) ◽  
pp. 007-007 ◽  
Author(s):  
Javier Grande ◽  
Joan Solà ◽  
Spyros Basilakos ◽  
Manolis Plionis
Keyword(s):  
Structure Formation ◽  
Hubble Expansion ◽  
Cosmic Evolution

Social development of modern Russia: trends, risks, prospects

2018 ◽  
pp. 76-89
Author(s):  
E. M. Avraamova ◽  
V. N. Titov
Keyword(s):  
Middle Class ◽  
Social Development ◽  
Social Structure ◽  
Structure Formation ◽  
Resource Availability ◽  
Social Dynamics ◽  
Quantitative Estimation ◽  
Resource Potential ◽  
Institutional Conditions ◽  
Resource Characteristics

The analysis of present-time directions in the study of social development has allowed to identify the resource approach as the most productive one which enables to assess social dynamics through the range of resource characteristics of different population groups and abilities of the relevant groups to apply development resources in the current economic and institutional conditions. Basing on the sociological survey conducted by ISAP RANEPA, the quantitative estimation of material and social recourses of the population has been made; integral values of the resource potential have been calculated as well. The issues of social structure formation are analyzed through the aspect of resource availability; the barriers of Russian middle-class enlargement are defined.

Characteristics Of The Structure Formation Of Gypsum Binder Modified With Zinc Hydrosilicates

2020 ◽  
pp. 40-46
Keyword(s):  
Synergistic Effect ◽  
Physicochemical Properties ◽  
Structure Formation ◽  
Silicic Acid ◽  
Chemical Properties ◽  
Crystal Formation ◽  
Ability To Act ◽  
Chemical Factors ◽  
Sorption Characteristics

The authors' methodic for assessing the role of chemical and physic-chemical factors during the structure formation of gypsum stone is presented in the article. The methodic is also makes it possible to reveal the synergistic effect and to determine the ranges of variation of controls factors that ensure maximum values of such effect. The effect of a micro-sized modifier based on zinc hydro-silicates on the structure formation of building gypsum is analyzed and corresponding dependencies are found. It is shown that effects of influence of modifier on the properties of gypsum compositions are determined by chemical properties of modifier. Among the mentioned properties are sorption characteristics (which depend on the amount of silicic acid and its state) and physicochemical properties - the ability to act as a substrate during crystal formation. The proposed method can also be extended to other binding substances and materials. This article contributes to the understanding of the processes that occur during the structure formation of composites, which will make it possible to control the structure formation in the future, obtaining materials with a given set of properties.

Study Of Structure Formation Of Organic-Mineral Compositions With Fibrous Filler By Electron Microscopy Method

2019 ◽  
pp. 41-47
Keyword(s):  
Electron Microscopy ◽  
Structure Formation ◽  
Mineral Composition ◽  
Bending Strength ◽  
Cement Stone ◽  
Hydrated Cement ◽  
Fibrous Filler ◽  
Organic Mineral ◽  
Microscopy Method ◽  
Mineral Compositions

The article presents the study of processes of structure formation of cement stone and products of hardening of organic-mineral compositions with fibrous filler (shavings) by the electronic scanning microscopy method. It is established that the additive-free cement stone at the age of 28 days has a dense and homogeneous structure, consists of calcium hydro-silicates, Portlandite and calcite - newgrowths characteristic for cement systems. Cellulose fibers, which make up the bulk of the substance of shavings, are sufficiently active, which determines the high adhesion of the hydration products of the cement binder to their surface. It is shown that the introduction of shavings into the organo-mineral composition leads to inhibition of cement hydration processes. Organo-mineral compositions with different shavings content (two compositions) were analyzed. The first composition is characterized by a fairly dense structure, the cement stone consists of globular nanoscale nuclei of hydrosilicates, Portlandite and calcite. The second composition has a loose porous structure, cement stone consists of non-hydrated cement grains, newgrowths are represented by calcite and vaterite. The structure of the contact zone "osprey fiber-cement stone" in the organo-mineral composition of the first composition indicates a good adhesion of the filler surface with the phases of hydrated cement. The use of shavings as a fibrous filler (the first composition) increases the tensile and bending strength, as well as the wear resistance of organo-mineral compositions. The data obtained by scanning electron microscopy are confirmed by the results of studying the processes of structure formation of cement stone by quantitative x-ray phase analysis.

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