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Register a new userThe large scale structure formation in an expanding universe
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In this paper, we analyze the effects of expansion on large scale structure formation in our Universe. We do that by incorporating a cosmological constant term in the gravitational partition function. This gravitational partition function with a cosmological constant is used for analyzing the thermodynamics of this system. We analyze the virial expansion for this system, and obtain its equation of state. It is observed that the generalization of this equation of state is like the Van der Waals equation. We also analyze a gravitational phase transition in this system using the mean field theory. We construct the cosmic energy equation for this system of galaxies, and discuss its consequences. We obtain and analyze the distribution function for this system, using the gravitational partition function. We also compare the results obtained in this paper with the observational data.
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The Hubble law, determined from the distance modulii and redshifts of galaxies, for the past 80 years, has been used as strong evidence for an expanding universe. This claim is reviewed in light of the claimed lack of necessary evidence for time dilation in quasar and gamma-ray burst luminosity variations and other lines of evidence. It is concluded that the observations could be used to describe either a static universe (where the Hubble law results from some as-yet-unknown mechanism) or an expanding universe described by the standard Lambda cold dark matter model. In the latter case, size evolution of galaxies is necessary for agreement with observations. Yet the simple non-expanding Euclidean universe fits most data with the least number of assumptions. From this review it is apparent that there are still many unanswered questions in cosmology and the title question of this paper is still far from being answered.
Our goal is to interpret the energy equation from Doubly Special Relativity (DSR) of Magueijo-Smolin with an invariant Planck energy scale in order to obtain the speed of light with an explicit dependence on the background temperature of the expanding universe. We also investigate how other universal constants, including the fine structure constant, have varied since the early universe and, thus, how they have evoluted over the cosmological time related to the temperature of the expanding universe. For instance, we show that both the Planck constant and the electron charge were also too large in the early universe. However, we finally conclude that the fine structure constant has remained invariant with the age and temperature of the universe, which is in agreement with laboratory tests and some observational data.
In the standard picture of cosmological structure formation, the Universe we see today is evolved under the gravitational instability from tiny random fluctuations. In this talk I discuss the onset of non-linearity in the large scale structure formation of the Universe when the linear perturbation theory break downs. Using 1D Zeldovich Approximation which provides an exact solution for density evolution, I illustrate two effects: mode spawning and mode merging and their connection to mode coupling. Those mode couplings (quadratic, cubic >...etc.) from gravitational clustering are in fact what the polyspectra (bispectrum, trispectrum...etc.) are meant to measure.
A short overview is given on the development of our present paradigm of the large scale structure of the Universe with emphasis on the role of Ya. B. Zeldovich. Next we use the Sloan Digital Sky Survey data and show that the distribution of phases of density waves of various scale in the present-day Universe are correlated. Using numerical simulations of structure evolution we show that the skeleton of the cosmic web was present already in an early stage of the evolution of structure. The positions of maxima and minima of density waves (their phases) are the more stable, the larger is the wavelength. The birth of the first generation of stars occured most probably in the central regions of rich proto-superclusters where the density was highest in the early Universe.
We show that entanglement can be used to detect spacetime curvature. Quantum fields in the Minkowski vacuum are entangled with respect to local field modes. This entanglement can be swapped to spatially separated quantum systems using standard local couplings. A single, inertial field detector in the exponentially expanding (de Sitter) vacuum responds as if it were bathed in thermal radiation in a Minkowski universe. We show that using two inertial detectors, interactions with the field in the thermal case will entangle certain detector pairs that would not become entangled in the corresponding de Sitter case. The two universes can thus be distinguished by their entangling power.
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