Quiescent Cosmology and the Final State of the Universe

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2022

The discovery of accelerated expansion of the Universe opened up the possibility of new scenarios for the doom of our space–time, besides eternal expansion and a final contraction. In this paper, we review the chances that may await our universe. In particular, there are new possible singular fates (sudden singularities, big rip, etc.), but there also other evolutions that cannot be considered as singular. In addition to this, some of the singular fates are not strong enough in the sense that the space–time can be extended beyond the singularity. For deriving our results, we make use of generalized power and asymptotic expansions of the scale factor of the Universe. This article is part of the theme issue ‘The future of mathematical cosmology, Volume 1’.

Cosmology: Cosmoether model, 2022

BY WAY OF PROLOGUE The present book was born from a need: to support with much more property some ideas that I applied in my book "Plate Tectonics: A New Vision", published in 2018, on amazon.com in digital version in English, Spanish and French. In that my book corresponding to my specialty, I resorted to some rather bold hypotheses about the existence of nuclear fusion reactions in the interior of our planet Earth in the conditions of increased pressures provided by the sole accumulation of silicate matter originally contained in the mantle. This statement brought with it a whole conception of the formation of the Universe that went against the current trend of current official science that postulates what has come to be called the "standard model of the formation of the Universe" which, according to my opinion, leads to extravagant assumptions and statements such as the existence of dark matter and dark energy and the belief in the existence of "singular" moments in the formation of the Universe. In the present work, I had to refine these my ideas and transform them into a coherent system that dared to put forward a whole theory of the origin of the universe as a new alternative to the Big Bang theory and other fashionable claims. The basic ideas of this new approach to the origin of the Universe, deeply questions the interpretation given to controversial phenomena such as "the red shift"; the curvature of space-time, and the postulates of an expanding universe. These postulates will also question the idea of a universe with a beginning and an end as a dynamic approach to the origin of matter. My position does not defend at all the idea of a "stationary" universe, although it has points in common with this theory, such as the postulate of its infinity in space and time. A Universe, whose matter is in continuous development, with the appearance of increasingly complex and, in many cases, irreversible structures, represents the universe in which I believe we live, which has nothing stationary about it. I make an explicit abandonment to the affirmations that matter evolves almost unilaterally through catastrophic or exceptional acts and although I recognize the leap that must exist by accumulation of the small quantitative changes of the phenomena until producing the new quality of matter, my approaches are much more attached to the sense of objectivity that science must have, especially in the present historical stage of advancement of scientific knowledge. I must confess that my knowledge in astronomy, physics and the high mathematics that the subject of the present investigation requires, have been limited due to my basic engineering formation. Nor could they be further improved as was my original intention since I was still an engineering student in a Bolivian university. Although I made every effort to fulfill my dreams of training in theoretical physics, I was not able to achieve my goal, but I am grateful to life that has allowed me to reach at least at the advanced age that I have, to touch the dream cherished since my childhood to refer to the problems of the Universe that have always intrigued me. I hope that those who come to read my writing will do so with the desire to find new ideas in the evolution of natural phenomena and that they will not spare their criticism of the ideas presented here, since there is no better way to advance scientific knowledge than with an open mind and intellectual honesty. La Paz, June 01, 2022 The author

Physics Letters B, 2009

In this paper we study the final fate of the universe in modified theories of gravity. As compared with general relativistic formulations, in these scenarios the Friedmann equation has additional terms which are relevant for low density epochs. We analyze the sort of future singularities to be found under the usual assumption the expanding Universe is solely filled with a pressureless component. We report our results using two schemes: one concerned with the behavior of curvature scalars, and a more refined one linked to observers. Some examples with a very solid theoretical motivation and some others with a more phenomenological nature are used for illustration.

2002

Much of the published work regarding the Isotropic Singularity is performed under the assumption that the matter source for the cosmological model is a barotropic perfect fluid, or even a perfect fluid with a γ-law equation of state. There are, however, some general properties of cosmological models which admit an Isotropic Singularity, irrespective of the matter source. In particular, we show that the Isotropic Singularity is a point-like singularity and that vacuum space-times cannot admit an Isotropic Singularity. The relationships between the Isotropic Singularity, and the energy conditions, and the Hubble parameter is explored. A review of work by the authors, regarding the Isotropic Singularity, is presented.

Physical Review D, 2009

We present a novel cosmological model in which scalar field matter in a biaxial Bianchi IX geometry leads to a non-singular 'pancaking' solution: the hypersurface volume goes to zero instantaneously at the 'Big Bang', but all physical quantities, such as curvature invariants and the matter energy density remain finite, and continue smoothly through the Big Bang. We demonstrate that there exist geodesics extending through the Big Bang, but that there are also incomplete geodesics that spiral infinitely around a topologically closed spatial dimension at the Big Bang, rendering it, at worst, a quasi-regular singularity. The model is thus reminiscent of the Taub-NUT vacuum solution in that it has biaxial Bianchi IX geometry and its evolution exhibits a dimensionality reduction at a quasi-regular singularity; the two models are, however, rather different, as we will show in a future work. Here we concentrate on the cosmological implications of our model and show how the scalar field drives both isotropisation and inflation, thus raising the question of whether structure on the largest scales was laid down at a time when the universe was still oblate (as also suggested by ). We also discuss the stability of our model to small perturbations around biaxiality and draw an analogy with cosmological perturbations. We conclude by presenting a separate, bouncing solution, which generalises the known bouncing solution in closed FRW universes.

Journal of Physics: Conference Series, 2005

We review recent work and present new examples about the character of singularities in globally and regularly hyperbolic, isotropic universes. These include recent singular relativistic models, tachyonic and phantom universes as well as inflationary cosmologies.

Universal Journal of Physics and Application, 2014

In this paper we show how the inhomogeneity in the matter distribution produced until the time of the last scattering surface in the light of some spatially homogeneous but anisotropic models, produced anisotropies that on large angular scales (larger than ϑ ∼ > 2 •) not differ from those considered in Friedmann-Lemaître-Robertson-Walker (FLRW) geometries. For these anisotropic models the mark left in the cosmic microwave background radiation by fluctuations density primordial, in the form of a fractional variation of temperature of this radiation, is governed by the same expression which is used for FLRW models. More specifically, under adiabatic initial conditions, the classical Sachs-Wolfe effect is recovered, since the anisotropy of the global expansion is small at the time of the last scattering surface. This conclusion is in agreement with previous work on the same anisotropic models, where they undergo a process of 'isotropization' to the extent that the observations are unable to distinguish them from the FLRW models, if the Hubble parameters along the orthogonal directions are assumed approximately equal to the current present epoch. We considered upper bounds for the current values of the anisotropic parameters imposed by COBE observations.

General relativity and gravitation, 1989

By means of exponential laws we show a Bianchi Type I model of the universe where we define overall deceleration and Hubble's parameters that have constant values. We employ a convenient relation for defining the “radius” of the universe. Pressure and density have constant values, too.

Journal of Cosmology and Astroparticle Physics, 2016

In homogeneous and isotropic Friedmann-Robertson-Walker cosmology, the topology of the universe determines its ultimate fate. If the Weak Energy Condition is satisfied, open and flat universes must expand forever, while closed cosmologies can recollapse to a Big Crunch. A similar statement holds for homogeneous but anisotropic (Bianchi) universes. Here, we prove that arbitrarily inhomogeneous and anisotropic cosmologies with "flat" (including toroidal) and "open" (including compact hyperbolic) spatial topology that are initially expanding must continue to expand forever at least in some region at a rate bounded from below by a positive number, despite the presence of arbitrarily large density fluctuations and/or the formation of black holes. Because the set of 3-manifold topologies is countable, a single integer determines the ultimate fate of the universe, and, in a specific sense, most 3-manifolds are "flat" or "open". Our result has important implications for inflation: if there is a positive cosmological constant (or suitable inflationary potential) and initial conditions for the inflaton, cosmologies with "flat" or "open" topology must expand forever in some region at least as fast as de Sitter space, and are therefore very likely to begin inflationary expansion eventually, regardless of the scale of the inflationary energy or the spectrum and amplitude of initial inhomogeneities and gravitational waves. Our result is also significant for numerical general relativity, which often makes use of periodic (toroidal) boundary conditions.

arXiv: General Relativity and Quantum Cosmology, 1998

In 1985 Goode and Wainwright devised the concept of an isotropic singularity. Since that time, numerous authors have explored the interesting consequences, in mathematical cosmology, of assuming the existence of this type of singularity. In this paper, we collate all examples of cosmological models which are known to admit an isotropic singularity, and make a number of observations regarding their general characteristics.

ResearchGate, 2024

Background: The concept of the universe's lifecycle, from its initial singularity to its potential collapse and rebirth, represents a profound area of cosmological inquiry. This theory explores the possibility that the universe undergoes infinite cycles of expansion and contraction, akin to stellar evolution and black hole formation. Objectives: This study aims to propose a unified theory of the universe's cyclical nature, examining how the universe's density and structure evolve over time, leading to eventual collapse and rebirth. We seek to integrate current cosmological models with the concept of perpetual cycles of cosmic renewal. Methods: Utilizing a combination of theoretical physics, cosmological observations, and mathematical modeling, we investigate the implications of a universe that contracts into a singularity and subsequently re-expands, forming a new cosmic structure. Results: Our analysis suggests that the universe's lifecycle may mirror the behavior of collapsing stars, eventually leading to a state of high density that triggers a new cycle of expansion. This cyclical model aligns with current understanding of black hole dynamics and cosmic evolution. Conclusions: The proposed theory offers a novel perspective on the universe's fate, challenging traditional notions of eternal expansion. By integrating the concept of cyclic rebirth, this research contributes to a deeper understanding of cosmic evolution and suggests avenues for further exploration into the fundamental nature of the universe.

A dynamical study of the universe is briefly reviewed in the early stage (inflation) as well as in the late era (cosmic doomsday). The cosmological model of the expanding universe, governed by the Friedman equations, is explored. It is indicated that the expansion is proved to be accelerated experimentally. In the early phase, just after the big bang, the expansion of the universe is rapid and approximately exponential, which is termed as inflation. The mathematical formulation and physical significance of the inflation is discussed briefly. A number of inflationary models are also listed. The ultimate fate of the universe is briefed in the scenario of dark energy and phantom energy. The possible singularities, arising in the phantom energy era, are also discussed.

The automatic translation of French into English does not rule out errors in terms and incorrect turns of phrase. Thank you for your comprehension Astrophysics and cosmology are twin sciences that would like to be accurate. They are, however, too burdened with assumptions, assumptions, uncertainties, and imprecision for us to be convinced of. The following reflection, which is intended to be devoid of any intention of proselytism, has already been and will continue to be subject to frequent corrections and additions. Free reading and downloading, it will not cease to be regularly updated on: lirenligne.net These few pages would like to tell the story of our Universe as you probably never imagined it. You must know how to "ask yourself questions as a child with an adult brain," would have said Albert Einstein. He could have added that the child's own, in addition to not yet having a mind full of preconceived ideas, is to think without necessarily relying on words. All the difficulty, then, is to convert these ideas not really formulated, in writing. Moreover, on a vast subject, a need for precision in formatting does not facilitate rhetoric. If you live on certainties, this book is probably not for you. Among others, how do we manage to represent our Universe on a subatomic scale? To describe this invisible world, it seems that we can only rely on concepts, specific terms invented pour interpret what is beyond our feelings. This scientific talk responds to the need to build a physics consistent with what we are given to observe. But, in quantum physic (the physics of the infinitely small), we quickly realize that our vocabulary is not really appropriate and that it often becomes necessary to reason by comparisons, images, allegories, metaphors. Our thinking reveals its limits at the same time as the failure of words. The difficulty is to imagine and conceive, what happens on a scale where things don't really refer anymore to what makes our well-known reality. In quantum mechanics, talking about corpuscles, orbits, spatial positioning, gravitation seems no completely appropriate, but nevertheless allows us to approach the Universe in a dimension where the call to the imaginary becomes unavoidable. Everything that follows is the fruit of a reflection whose added title «Tales and legends of the Cosmos» may suggest that it wants to be devoid of any Foreword Before continuing, it should be noted that this proposed representation of the world around us is an overall model, one could not be more open on the foundations of a Universe that surpasses us by its very nature and complexity. To want to explain the purpose of this, should logically be a strictly scientific approach. However, to exclude any philosophical or metaphysical thought from this reflection would be a challenge. With all the reservations of convenience, these few lines, which are not absent from considerations on the margins and critical annotations, would like to describe, in as simple terms as possible, what certain scientific theories and hypotheses which inspired this essay, apply themselves to wanting to demonstrate in a more elaborate way but often less accessible. To popularize ideas that appeal to particularly abstract notions or that rely on relatively hermetic mathematical expressions, can leave one perplexed. The data for this are often insufficient and inevitably lead to interpretation and extrapolation. And as always, going beyond what makes case law in the scientific world, can be interpreted as a predisposition to speculation. For personal convenience and for the sake of clarity, there is rather sober references to mathematical formulations. Developments in nuclear physics will be concise. But can we make simple in this complex field and perhaps poorly assimilated on certain points? Black holes, dark matter, dark energy, unfinished unification theories, universe beyond the visible, superposition of states, virtual particles... Is everything really so obscure and elusive? Only one thing is certain: nothing can be taken for granted on subject as vast as it is confusing, and this thought which wants to be exhaustive, may seem relatively dissenting. Nevertheless, it is a selection of responses in search of coherence and devoid of spirituality response to many questions. This essay, undoubtedly, insufficiently developed, and which invites controversy, proposes an original and relatively logic approach of the Universe in the continuity of current knowledge. It is also a way to revive a debate that is far removed from the daily concerns of our existence. Undoubtedly, our priorities are called to evolve, as our living conditions change in a society that is more open, more critical and more curious, but

The whole aspect of Universe on which we are residing is different than we thought, with different approach towards the beginning of Universe, we are simulating our work that cause this beginning. Big Bang theory is the engine that covers up the beginning of the Universe via huge chemical reaction in the Space. This paper leads you to describe the whole aspect of the Universe and its beginning. This paper includes the thermodynamics cycles and its other relevance. The paper also address – how this universe is going to reform again and again. The most important part of this paper is the Gravitational Singularity and Four Fundamental Forces of Nature. As the nomenclature of Universe itself derived himself as-Universe word signifies " one versatile " it means that a system that is continuously changing their state.

Gravitation and Cosmology, 2008

In this paper we present a new simple method of construction of infinite number of solutions of Freidmann equations from the already known ones, which allows for a startling conclusion of practical impossibility of correct predictions on the universe's future dynamics which are based solely on astronomical observations on the value of a scale factor. In addition, we present particular examples of newly constructed solutions, such as the ones, describing the smooth dynamical (de)phantomization, and the models lacking the events horizons (both in classical and brane world cases). The generalization of the method to the simplest anisotropic universes are presented as well.