scholarly journals An Old Universe in K-Essence Cosmology

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Rong-Jia Yang ◽  
Shuang Nan Zhang ◽  
Bohai Chen ◽  
Jing-Zhao Qi

Models in which the Lagrangian contains only a kinetic factor and does not depend explicitly on the field itself in k-essence cosmology are considered. In the case of a constant potential, we obtain an exact analytic solution of k-essence, wk=−(3α−2)/3α, under a simple hypothesis, a=a0(t/t0)α, but without any assumption about the form of F(X). In purely kinetic k-essence model, the acceleration can only be induced after the matter-dominated epoch; the Universe is about 33.5−3.4+4.2 Gyr old now and about 3.1 Gyr old at z=3.9 which is consistent with the fact of quasar observation, while this observation contradicts with the prediction of ΛCDM model, and the year where a transition from deceleration to acceleration expansion is about from 18.43 Gyr to 25.2 Gyr after the beginning of the Universe. These results may offer clues to test observationally the k-essence scenario in the future.

2014 ◽  
Vol 11 (02) ◽  
pp. 1460014 ◽  
Author(s):  
Winfried Zimdahl

Interactions inside the cosmological dark sector influence the cosmological dynamics. As a consequence, the future evolution of the Universe may be different from that predicted by the ΛCDM model. We review main features of several recently studied models with nongravitational couplings between dark matter and dark energy.


2019 ◽  
Vol 24 (2) ◽  
pp. 343-367
Author(s):  
Roberto Paura

Transhumanism is one of the main “ideologies of the future” that has emerged in recent decades. Its program for the enhancement of the human species during this century pursues the ultimate goal of immortality, through the creation of human brain emulations. Therefore, transhumanism offers its fol- lowers an explicit eschatology, a vision of the ultimate future of our civilization that in some cases coincides with the ultimate future of the universe, as in Frank Tipler’s Omega Point theory. The essay aims to analyze the points of comparison and opposition between transhumanist and Christian eschatologies, in particular considering the “incarnationist” view of Parousia. After an introduction concern- ing the problems posed by new scientific and cosmological theories to traditional Christian eschatology, causing the debate between “incarnationists” and “escha- tologists,” the article analyzes the transhumanist idea of mind-uploading through the possibility of making emulations of the human brain and perfect simulations of the reality we live in. In the last section the problems raised by these theories are analyzed from the point of Christian theology, in particular the proposal of a transhuman species through the emulation of the body and mind of human beings. The possibility of a transhumanist eschatology in line with the incarnationist view of Parousia is refused.


2017 ◽  
Vol 95 (1) ◽  
pp. 21-24
Author(s):  
Jung-Jeng Huang ◽  
Meng-Jong Wang

We propose that the Hubble law can be viewed as the de Broglie relation on a cosmic scale. We show how the entropy of the Universe can be estimated in the ΛCDM model and its extended version, and how the quest for the maximal entropy leads to the energy constituents of the current Universe.


Problemos ◽  
2009 ◽  
Vol 76 ◽  
pp. 52-65
Author(s):  
Vytautas Rubavičius

Straipsnyje grindžiama nuomonė, jog postmodernybė yra iš modernybės kylantis kapitalizmo sistemos būvis, kuriam būdinga gyvybės suprekinimas ir suišteklinimas. Postmodernybę charakterizuoja populiariosios ir medijų kultūros išplitimas. Tos kultūros apima ne tik kultūros prekes, bet ir vartojimo būdus, įgūdžius ir jų lavinimą. Pastaruoju metu jos kuria nemirtingumo vaizdiniams bei nuojautoms palankią kultūrinę, intelektinę ir pasaulėvaizdinę terpę, kurioje struktūriškai įsitvirtina genetinis diskursas ir jo nustatomos žmogaus ir jo gyvenamo pasaulio aiškinimo gairės. Svarbus šio diskurso bruožas yra technologinis inžinerinis jo pobūdis, išryškėjęs susiejant nano ir biotechnologijas, kuriomis tikimasi įveikti gyvąją ir negyvąją gamtą skiriančią prarają, iš reikalingų atomų bei molekulių kuriant reikalingų ląstelių dalis ir klonuojant gyvas būtybes. Gyvybė suprekinama ir suišteklinama patentuojant gyvybės elementus – genus ir su jais susijusius procesus. Daroma išvada, jog visi genetikos, informatikos ir kitų mokslų laimėjimai, teikiantys žmogaus gyvenimo ilginimo galimybių, kurios palaiko gundančią nemirtingumo idėją, jau yra persmelkti prekinių santykių, tad ir pats nemirtingumas įmanomas tik kaip prekė. Aptariami kai kurie evoliuciniai ir religiniai techno sapiens sampratos aspektai. Detaliau gvildenamos dvi „nemirtingumo“ versijos: Z. Baumano, kuris nemirtingumo pažadą sieja su kompiuterinės technikos plėtra prasidėjus „Antrajai medijų erai“, ir J. Baudrillard’o, tegiančio, jog klonavimo technologijos „apgręžia“ evoliuciją ir žmogų gundo virusiniu ar vėžiniu belyčiu nemirtingumu.Pagrindiniai žodžiai: genetinis diskursas, klonavimas, medijų kultūra, nanobiotechnologijos, nemirtingumas, suprekinimas.Genetic Discourse in Media Culture: Temptation by Commodified ImmoralityVytautas Rubavičius   SummaryPostmodernity is maintained as a stage of the development of capitalism. The difference between modernity and postmodernity is explained in relation to the new sphere of commodification and resourcification, namely, that of life and of all natural living processes. Postmodern media culture, or popular culture, is peopled by signs of immortality and various kinds of immortals – cyborgs, clones, zombies, immortal human beings and others. Thus, culture accustoms a consumer to immortals and immortality which is concidered as the main goal of a human being and evolution. By nano-bio-technologies and genetic discourse this goal is made scientifically valid, thus reachable. Genetic discourse is becoming the fundamental world-view providing focal landmarks for the emerging future. Media culture supports the spreading of genetic discourse and facilitates its understanding. The temptation by immortality can be considered as a version of modernist ideology of human liberation from various natural, social and heavenly bonds. This liberation, and also secularization, is supported by a scientific genetic technological discourse which is becoming a stimulating factor of postmodern media production. The genetic explanation of the world is particularly handy for technological reflexivity: the entire world is as if encapsulated into human genes, which become the principle explaining the mystery of life, evolution and the future of humanity, thus rendering power to produce the human proper form and the future of people. All the possibilities stemming from the new genetic and biotech discoveries fell under the regulation of property relations by patenting, thus making “immortality” – as a temptation and brand – not only an exeptional commodity, but also a political tool and a commodifying force. As the relationships of private property have penetrated natural biogenetic diversity and, having turned it into a resource, the cognitive subject has reached the goal to secularise the Universe, which he has set for himself: only he as the owner and producer of genes lures people with the eternal shapes of the clones and their genetic information, which will be sustained in any location of the Universe. The temptation by “immortality” will become even stronger when the genetic code is mastered. The future of humanity is related to the mixed forms of life, trans-genic or otherwise genetically modified organisms and techno-human forms that will help to postpone, and later to conquer, death. Even thinkers with religious tendencies perceive the technological improvement of human beings as their evolution towards the techno sapiens and consider such a development as an advancement towards the Kingdom of God. The technologization of human beings is imagined in terms of their divination. Yet in this case the character of contemporary science secularising God and obliterating the perception of divinity is overlooked. Two versions of immortality are analyzed more closely – that of Z. Bauman, who links it with the development of computer technologies, and that of J. Baudrillard, who gives a warning that by cloning technologies humanity is trying to inverse the evolution and to return to the undifferentiated state of cells. The conclusion is drawn that regardless of how we understand ‘immortality,’ argue over its reality or unreality, all possibilities to prolong human life granted by genetics, informatics and other advances in science and technologies, which support the tempting idea of immortality, have already been penetrated by commodity relationships; therefore, “immortality” itself will be available only as a commodity.Keywords: cloning, commodification, genetic discourse, immortality, media culture, nano-bio-technologies.


1972 ◽  
Vol 25 (2) ◽  
pp. 207 ◽  
Author(s):  
DT Pegg

In conventional electrodynamic theory, the advanced potential solution of Maxwell's equations is discarded on the ad hoc basis that information can be received from the past only and not from the future. This difficulty is overcome by the Wheeler?Feynman absorber theory, but unfortunately the existence of a completely retarded solution in this theory requires a steady-state universe. In the present paper conventional electrodynamics is used to obtain a condition which, if satisfied, allows information to be received from the past only, and ensures that the retarded potential is the only consistent solution. The condition is that a function Ua of the future structure of the universe is infinite, while the corresponding function Ur of the past structure is finite. Of the currently acceptable cosmological models, only the steady-state, the open big-bang, and the Eddington-Lema�tre models satisfy this condition. In these models there is no need for an ad hoc reason for the preclusion of advanced potentials.


1943 ◽  
Vol 5 (2) ◽  
pp. 156-176
Author(s):  
John U. Nef

In An article published in the July 1942 number of the Review of Politics, I suggested that contemporary learned men who deny the existence of truth, virtue, or beauty, are led into a dilemma. Either they must confine truth to positive science, where the results are always tentative and incomplete with respect to the universe in which human beings have to move, or else they must believe that people generally will be inclined towards good and wise actions even though learning refuses to admit the existence of standards, apart from the rules of conduct that can be derived from positive science. The second view, we suggested, involves the admission that impersonal standards do exist, independent of positive science. We might conclude that the nourishment of these standards by means of the intellect, and with the help of results obtained by science, ought to be the supreme task of learning.


2011 ◽  
Vol 01 ◽  
pp. 228-233
Author(s):  
YUNGUI GONG

The growth rate of matter perturbation and the expansion rate of the Universe can be used to distinguish modified gravity and dark energy models. Remarkably, the growth rate can be approximated as Ωγ. We discuss the dependence of the growth index γ on the dimensionless matter energy density Ω for a more accurate approximation of the growth factor. The observational data are used to fit different models. The data strongly disfavor the Dvali-Gabadadze-Porrati model. For the ΛCDM model, we find that [Formula: see text]. For the Dvali-Gabadadze-Porrati model, we find that [Formula: see text].


2003 ◽  
Vol 70 (3) ◽  
pp. 426-435 ◽  
Author(s):  
D. Galic ◽  
C. O. Horgan

Recent advances in smart structures technology have lead to a resurgence of interest in piezoelectricity, and in particular, in the solution of fundamental boundary value problems. In this paper, we develop an analytic solution to the axisymmetric problem of an infinitely long, radially polarized, radially orthotropic piezoelectric hollow circular cylinder rotating about its axis at constant angular velocity. The cylinder is subjected to uniform internal pressure, or a constant potential difference between its inner and outer surfaces, or both. An analytic solution to the governing equilibrium equations (a coupled system of second-order ordinary differential equations) is obtained. On application of the boundary conditions, the problem is reduced to solving a system of linear algebraic equations. The stress distribution in the tube is obtained numerically for a specific piezoceramic of technological interest, namely PZT-4. For the special problem of a uniformly rotating solid cylinder with traction-free surface and zero applied electric charge, explicit closed-form solutions are obtained. It is shown that for certain piezoelectric solids, stress singularities at the origin can occur analogous to those occurring in the purely mechanical problem for radially orthotropic elastic materials.


Author(s):  
Anna-Maria A. van Veggel

At the commencement of a new era in astrophysics, with added information from direct detections of gravitational-wave (GW) signals, this paper is a testament to the quasi-monolithic suspensions of the test masses of the GW detectors that have enabled the opening of a new window on the universe. The quasi-monolithic suspensions are the final stages in the seismic isolation of the test masses in GW detectors, and are specifically designed to introduce as little thermal noise as possible. The history of the development of the fused-silica quasi-monolithic suspensions, which have been so essential for the first detections of GWs, is outlined and a glimpse into the status of research towards quasi-monolithic suspensions made of sapphire and silicon is given. This article is part of a discussion meeting issue ‘The promises of gravitational-wave astronomy’.


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