scholarly journals Viscous Cosmology and the Cardy-Verlinde Formula

2003 ◽  
Vol 18 (12) ◽  
pp. 2145-2152 ◽  
Author(s):  
I. Brevik
Keyword(s):  
Invariant Theory ◽  
Casimir Energy ◽  
Point Of View ◽  
Generalized Entropy ◽  
Entropy Formula ◽  
Verlinde Formula ◽  
Bulk Viscous ◽  
The Universe ◽  
Formal Point ◽  
Entropy Of The Universe

The holographic principle in a radiation dominated universe is extended to incorporate the case of a bulk-viscous cosmic fluid. This corresponds to a nonconformally invariant theory. Generalization of the Cardy-Verlinde entropy formula to the viscous case appears to be possible from a formal point of view, although we question on physical grounds the manner in which the Casimir energy is evaluated in this case. Also, we consider in the present paper an observation recently made by Youm, namely that the entropy of the universe is no longer expressible in the conventional Cardy-Verlinde form if one relaxes the radiation dominance equation of state and instead merely assumes that the pressure is proportional to the energy density. We show that Youm's generalized entropy formula remains valid when the cosmic fluid is no longer ideal, but endowed with a constant bulk viscosity ζ.

scholarly journals QUANTUM EFFECTS FROM PARTICLE PRODUCTION ON BACKGROUND EVOLUTION AND CARDY–VERLINDE FORMULA IN f(R) GRAVITY

2011 ◽  
Vol 20 (13) ◽  
pp. 2449-2469 ◽  
Author(s):  
M. J. S. HOUNDJO ◽  
A. V. MONWANOU ◽  
JEAN B. CHABI OROU
Keyword(s):  
Particle Production ◽  
Space Dimension ◽  
Particle Creation ◽  
Quantum Effects ◽  
Dark Fluid ◽  
Verlinde Formula ◽  
Big Rip ◽  
The Universe ◽  
Entropy Of The Universe ◽  
Constant Dark

We investigate particle production in an expanding universe under the assumption that the Lagrangian contains the Einstein term R plus a modified gravity term of the form Rα, where α is a constant. Dark fluid is considered as the main content of the universe and the big rip singularity appears. Quantum effects due to particle creation is analyzed near the singularity and we find that for α ∈ ]½, 1[, quantum effects are dominant and the big rip may be avoided whereas for α ∈ J the dark fluid is dominant and the singularity remains. The Cardy–Verlinde formula is also introduced and its equivalence with the total entropy of the universe is checked. It is found that this can always occur in Einstein gravity while in f(R) gravity, it holds only for [Formula: see text], n being the space dimension, corresponding to the situation in which the big rip cannot be avoided.

scholarly journals Cardy-Verlinde Formula of Noncommutative Schwarzschild Black Hole

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
G. Abbas
Keyword(s):  
Field Theory ◽  
Black Hole ◽  
Conformal Field Theory ◽  
Total Energy ◽  
Arbitrary Dimension ◽  
Casimir Energy ◽  
Schwarzschild Black Hole ◽  
Conformal Field ◽  
Entropy Formula ◽  
Verlinde Formula

Few years ago, Setare (2006) has investigated the Cardy-Verlinde formula of noncommutative black hole obtained by noncommutativity of coordinates. In this paper, we apply the same procedure to a noncommutative black hole obtained by the coordinate coherent approach. The Cardy-Verlinde formula is entropy formula of conformal field theory in an arbitrary dimension. It relates the entropy of conformal field theory to its total energy and Casimir energy. In this paper, we have calculated the total energy and Casimir energy of noncommutative Schwarzschild black hole and have shown that entropy of noncommutative Schwarzschild black hole horizon can be expressed in terms of Cardy-Verlinde formula.

scholarly journals Universe of Discourse and Existence

Mathematics ◽  
2018 ◽  
Vol 6 (11) ◽  
pp. 272 ◽  
Author(s):  
José Usó-Doménech ◽  
Josué Nescolarde-Selva ◽  
Hugh Gash
Keyword(s):  
Necessary Conditions ◽  
Formal System ◽  
Point Of View ◽  
Epistemological Belief ◽  
Logical Problem ◽  
Metaphysical Problem ◽  
Widespread Belief ◽  
The Universe ◽  
Formal Point ◽  
Universe Of Discourse

There is a fairly widespread belief that the problem of existence is not an essential issue for logic. Logic, though formal, must deal with the problem of existence. However, logic should be limited to describing “formal existence” or “existence of a formal system”. However, the logical problem of existence and how to treat and resolve this problem differ completely from the corresponding metaphysical problem. It is possible to deduce that formal existence is nothing other than belonging to the universe of discourse, so proposing a solution to the logical problem of existence in an epistemological, rather than a metaphysical, context. In this paper, we conclude, from a formal point of view, no universe of discourse is given in advance; any universe of discourse that satisfies the necessary conditions can be used. The extended epistemological belief that there is a universe of discourse defined rigorously, which would be the true and should be “the universe of discourse of logic”, cannot be justified.

Changes in the Prognosis of Functional Psychoses Since the Days of Kraepelin

1967 ◽  
Vol 113 (501) ◽  
pp. 813-822 ◽  
Author(s):  
Örnulv Ödegård
Keyword(s):  
Special Problem ◽  
Point Of View ◽  
General Point ◽  
Course Of Illness ◽  
Dynamic Reasoning ◽  
Starting Point ◽  
Functional Psychoses ◽  
External Conditions ◽  
Point Of Departure ◽  
The Universe

My choice of Kraepelin as a point of departure for this lecture has definite reasons. If one wants to stay within the field of clinical psychiatry (as opposed to psychiatric history), that is as far back as one can reasonably go. By this no slight is intended upon the pre-Kraepelinian psychiatrists. For our topic Henry Maudsley would indeed have been a most appropriate starting point, and by no means for reasons of courtesy. His general point of view is admirably sound as a basis for the scientific study of prognosis in psychiatry. I quote: “There is no accident in madness. Causality, not casualty, governs its appearance in the universe, and it is very far from being a good and sufficient practice simply to mark its phenomena and straightway to pass on as if they belonged not to an order but to a disorder of events that called for no explanation.” On the special problem of prognosis he shows his clinical acumen by stating that the outlook is poor when the course of illness is insidious, but this only means that these cases develop their psychoses on the basis of mental deviations which go very far back in the patient's life, so that in fact they are generally in a chronic stage at the time of their first admission to hospital. Here he actually corrects a mistake which is still quite often made. He shows his dynamic attitude when he says that prognosis is to a large extent modified by external conditions, in particular by the attitude of friends and relatives. Maudsley's dynamic reasoning was limited by the narrow framework of the degeneration hypothesis of those days. He had a sceptical attitude towards classification, which he regarded as artificial and dangerously pseudo-exact. His own classification was deliberately provisional, with very wide groups. He held that a description of various sub-forms of chronic insanity was useless, as it would mean nothing but a tiresome enumeration of unconnected details.

scholarly journals Estimate of energy constituents of the universe in ΛCDM

2017 ◽  
Vol 95 (1) ◽  
pp. 21-24
Author(s):  
Jung-Jeng Huang ◽  
Meng-Jong Wang
Keyword(s):  
Maximal Entropy ◽  
Extended Version ◽  
Cosmic Scale ◽  
Λcdm Model ◽  
The Universe ◽  
Entropy Of The Universe

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.

PHILOSOPHY AND THE MEANING OF LIFE

Think ◽  
2021 ◽  
Vol 21 (60) ◽  
pp. 33-49
Author(s):  
William Lyons
Keyword(s):  
Human Life ◽  
Meaning Of Life ◽  
Point Of View ◽  
Eternal Life ◽  
Evolution Of The Universe ◽  
Life On Earth ◽  
The Universe

The author sets out to respond to the student complaint that ‘Philosophy did not answer “the big questions”’, in particular the question ‘What is the meaning of life?’ The response first outlines and evaluates the most common religious answer, that human life is given a meaning by God who created us and informs us that this life is just the pilgrim way to the next eternal life in heaven. He then discusses the response that, from the point of view of post-Darwinian science and the evolution of the universe and all that is in it, human life on Earth must be afforded no more meaning than the meaning we would give to a microscopic planaria or to some creature on another planet in a distant universe. All things including human creatures on Planet Earth just exist for a time and that is that. There is no plan or purpose. In the last sections the author outlines the view that it is we humans ourselves who give meaning to our lives by our choices of values or things that are worth pursuing and through our resulting sense of achievement or the opposite. Nevertheless the question ‘What is the meaning of life?’ can mean quite different things in different contexts, and so merit different if related answers. From one point of view one answer may lie in terms of the love of one human for another.

Evolution of the universe from the perspective of entropy and information

2021 ◽  
pp. 2150111
Author(s):  
Fei-Quan Tu ◽  
Bin Sun ◽  
Meng Wan ◽  
Qi-Hong Huang
Keyword(s):  
Information Entropy ◽  
Second Law Of Thermodynamics ◽  
Boltzmann Entropy ◽  
Evolution Of The Universe ◽  
Thermodynamic Entropy ◽  
Entire Universe ◽  
Low Entropy ◽  
The Relationship ◽  
The Universe ◽  
Entropy Of The Universe

Entropy is a key concept widely used in physics and other fields. At the same time, the meaning of entropy with different names and the relationship among them are confusing. In this paper, we discuss the relationship among the Clausius entropy, Boltzmann entropy and information entropy and further show that the three kinds of entropy are equivalent to each other to some extent. Moreover, we point out that the evolution of the universe is a process of entropy increment and life originates from the original low entropy of the universe. Finally, we discuss the evolution of the entire universe composed of the cosmological horizon and the space surrounded by it and interpret the entropy as a measure of information of all microstates corresponding to a certain macrostate. Under this explanation, the thermodynamic entropy and information entropy are unified and we can conclude that the sum of the entropy of horizon and the entropy of matter in the space surrounded by the horizon does not decrease with time if the second law of thermodynamics holds for the entire universe.

Review of: Рикёр П. Genesis, essence and substance in Plato and Aristotle. Course taught at the University of Strasbourg in 1953-1954 / transl. from french G. V. Vdovina. Moscow: Publishing house of humanitarian literature, 2019. 286 p. ISBN 978-5-87121-051-2

2019 ◽  
pp. 279-287
Author(s):  
Алексей Михайлович Гагинский
Keyword(s):  
20Th Century ◽  
Publishing House ◽  
Point Of View ◽  
History Of ◽  
The University ◽  
Formal Point

Курс лекций П. Рикёра, прочитанный более полувека назад, интересен по ряду причин. Во-первых, потому что он посвящён крайне важной теме — античной онтологии; во-вторых, потому что он был прочитан одним из ведущих философов XX в.; в-третьих, потому что этот философ был крупнейшим представителем герменевтического направления, вследствие чего особенно любопытно проследить, как он читает тексты, без преувеличения, самых важных философов в истории человечества. Впрочем, с формальной точки зрения есть некоторые сомнения в возожности исполнения замысла работы: П. Рикёр всё-таки не антиковед, его знание греческого языка, что видно из текста, весьма скромного уровня; кроме того, изданный текст представляет собой курс лекций, автор которых, как кажется, не столько хочет донести до слушателей результаты кропотливых исследований и продуманных идей, сколько разобраться вместе со студентами в античной онтологии. P. Ricoeur's course of lectures, delivered more than half a century ago, is interesting for a number of reasons. Firstly, because it is devoted to an extremely important topic - ancient ontology; secondly, because it was read by one of the leading philosophers of the 20th century; thirdly, because this philosopher was the biggest representative of the hermeneutic direction, so it is especially interesting to trace how he reads texts of, without exaggeration, the most important philosophers in the history of mankind. However, from the formal point of view, there are some doubts about the feasibility of the idea of the work: Ricoeur is not an antiquarian and his knowledge of Greek, as the text shows, is rather modest; besides, the published text is a course of lectures, the author of which seems to want not so much to convey the results of laborious research and elaborated ideas to his students, as to understand ancient ontology together with the students.

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