Cosmic Time: From the Big Bang to the Eternal Future

Author(s):  
Chris Impey
Keyword(s):  
Big Bang ◽  
2021 ◽  
Vol 4 (1) ◽  

Recent observations show that there are many more and much older black holes than previously known. What is particularly puzzling is that supermassive black holes containing more than a billion solar masses already existed in the very early universe. To date, there is no conclusive explanation for how such gravity monsters could have been created in such a short time after the Big Bang. The "Cosmic Time Hypothesis (CTH)" offers a solution to this problem [1]. According to this hypothesis, the early universe had much more time at its disposal than according to the "present-time scale" and the material-condensing forces were much stronger than now. Therefore, objects with extremely large masses could form in a very short "today-time".


Recent observations show that there are many more and much older black holes than previously known. What is particularly puzzling is that supermassive black holes containing more than a billion solar masses already existed in the very early universe. To date, there is no conclusive explanation for how such gravity monsters could have been created in such a short time after the Big Bang. The “Cosmic Time Hypothesis (CTH)” offers a solution to this problem [1]. According to this hypothesis, the early universe had much more time at its disposal than according to the “present-time scale” and the material-condensing forces were much stronger than now. Therefore, objects with extremely large masses could form in a very short “todaytime”.


2020 ◽  
Vol 497 (4) ◽  
pp. 4459-4471 ◽  
Author(s):  
Azadeh Fattahi ◽  
Alis J Deason ◽  
Carlos S Frenk ◽  
Christine M Simpson ◽  
Facundo A Gómez ◽  
...  

ABSTRACT We use magnetohydrodynamical simulations of Milky Way-mass haloes from the Auriga project to investigate the properties of surviving and destroyed dwarf galaxies that are accreted by these haloes over cosmic time. We show that the combined luminosity function of surviving and destroyed dwarfs at infall is similar in the various Auriga haloes, and is dominated by the destroyed dwarfs. There is, however, a strong dependence on infall time: destroyed dwarfs typically have early infall times of less than 6 Gyr (since the big bang), whereas the majority of dwarfs accreted after 10 Gyr have survived to the present day. Because of their late infall, the surviving satellites have higher metallicities at infall than their destroyed counterparts of similar mass at infall; the difference is even more pronounced for the present-day metallicities of satellites, many of which continue to form stars after infall, in particular for $M_{\rm star}\gt 10^7 \, {\rm M}_\odot$. In agreement with previous work, we find that a small number of relatively massive destroyed dwarf galaxies dominate the mass of stellar haloes. However, there is a significant radial dependence: while 90 per cent of the mass in the inner regions (${\lt}20\,$ kpc) is contributed, on average, by only three massive progenitors, the outer regions (${\gt}100\,$ kpc) typically have ∼8 main progenitors of relatively lower mass. Finally, we show that a few massive progenitors dominate the metallicity distribution of accreted stars, even at the metal-poor end. Contrary to common assumptions in the literature, stars from dwarf galaxies of mass $M_{\rm star}\lt 10^7 \, {\rm M}_\odot$ make up less than 10 per cent of the accreted, metal poor stars ([Fe/H] ${\lt}-3$) in the inner $50\,$ kpc.


2020 ◽  
Vol 1668 (1) ◽  
pp. 012028
Author(s):  
Viviana Mossa

Abstract The Big Bang Nucleosynthesis (BBN) describes the production of light nuclides occurred during the first minutes of cosmic time. It started with the accumulation of deuterium, whose primordial abundance is sensitive to the universal baryon density and to the amount of relativistic particles. Currently the main source of uncertainty to an accurate theoretical deuterium abundance evaluation is due to the poor knowledge of the D(p, γ)3He cross section at BBN energies. The present work wants to describe one of the two experimental approaches proposed by the LUNA collaboration, whose goal is to measure with unprecedented precision, the reaction cross section in the energy range 30 < Ecm[keV] < 300.


2021 ◽  
Vol 4 (3) ◽  

The Cosmic Time Hypothesis (CTH) presented in this paper is a purely axiomatic theory. In contrast to today's standard model of cosmology, the ɅCDM model, it does not contain empirical parameters such as the cosmological constant Ʌ, nor does it contain sub-theories such as the inflation theory. The CTH was developed solely on the basis of the general theory of relativity (GRT), aiming for the greatest possible simplicity. The simplest cosmological model permitted by ART is the Einstein-de Sitter model. It is the basis for solving some of the fundamental problems of cosmology that concern us today. First of all, the most important results of the CTH: It solves one of the biggest problems of cosmology the problem of the cosmological constant (Ʌ)-by removing the relation between and the vacuum energy density ɛv (Λ=0, ɛv > 0). According to the CTH, the vacuum energy density ɛv is not negative and constant, as previously assumed, but positive and time-dependent (ɛv ̴ t -2). ɛv is part of the total energy density (Ɛ) of the universe and is contained in the energy-momentum tensor of Einstein's field equations. Cosmology is thus freed from unnecessary ballast, i.e. a free parameter (= natural constant) is omitted (Ʌ = 0). Conclusion: There is no "dark energy"! According to the CTH, the numerical value of the vacuum energy density v is smaller by a factor of ≈10-122 than the value calculated from quantum field theory and is thus consistent with observation. The measurement data obtained from observations of SNla supernovae, which suggest a currently accelerated expansion of the universe, result - if interpreted from the point of view of the CTH - in a decelerated expansion, as required by the Einstein-de Sitter universe. Dark matter could also possibly not exist, because the KZH demands that the "gravitational constant" is time-dependent and becomes larger the further the observed objects are spatially and thus also temporally distant from us. Gravitationally bound local systems, e.g. Earth - Moon or Sun - Earth, expand according to the same law as the universe. This explains why Hubble's law also applies within very small groups of galaxies, as observations show. The CTH requires that the strongest force (strong nuclear force) and the weakest (gravitational force) at Planck time (tp ≈10-43 seconds after the "big bang") when all forces of nature are supposed to have been united in a single super force, were of equal magnitude and had the same range. According to the KZH, the product of the strength and range of the gravitational force is constant, i.e. independent of time, and is identical to the product of the strength and range of the strong nuclear force. At Planck time, the universe had the size of an elementary particle (Rp = rE ≈10-15 m). This value also corresponds to the range of the strong nuclear force (Yukawa radius) and the Planck length at Planck time. The CTH provides a possible explanation for Mach's first and second principles. It solves some old problems of the big bang theory in a simple and natural way. The problem of the horizon, flatness, galaxy formation and the age of the world. The inflation theory thus becomes superfluous. • The CTH provides the theoretical basis for the theory of Earth expansion • In Cosmic Time, there was no Big Bang. The universe is infinitely old. • Unlike other cosmological models, the CTH does not require defined "initial conditions" because there was no beginning. • The CTH explains why the cosmic expansion is permanently in an unstable state of equilibrium, which is necessary for a long-term flat (Euclidean), evolutionarily developing universe.


Author(s):  
Mohamed Abdalla Bakry ◽  
Ali Eid ◽  
A. Alkaoud

In this article, we assume that the beginning of the universe was before the Big Bang. In the beginning, all matter in the universe was combined in an infinitesimal spherical shape. This sphere was compressed to an incomprehensible value for a period, and then exploded and expanded time and space. We are referring to the negative time before the Big Bang. The evolution of the universe before the Big Bang, passing through the moment of the explosion to the end of the universe at the Big Rip, has been studied. In this article, we try to answer the questions; did the universe exist before the Big Bang? What is the origin of the universe and how did it arise? What are the stages of the evolution of the universe until the moment of the Big Rip? What is the length of time for the stages of this development?


Author(s):  
J. R. Lucas

This chapter argues for the position of temporal becoming across a wide variety of fields. The chapter's central sections address successively the metaphysics, physics and logic of time. It rebuts McTaggart's argument that temporal becoming involves a contradiction. It admits that special relativity's frame — dependence of simultaneity is inimical to temporal becoming. However it also argues that temporal becoming is rehabilitated both by general relativity's allowance of cosmic time functions and, more fundamentally, by the collapse of the wave-packet in quantum theory. Finally, the discussion considers the logic of time, especially tense logic, and applies this to recent cosmological speculation about the Big Bang and more generally to the idea of the beginning of time.


2006 ◽  
Vol 190 ◽  
pp. 15-15
Author(s):  
D CASTELVECCHI
Keyword(s):  
Big Bang ◽  

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