DOCSLIB.ORG

On the Concept of Time in Everyday Life and Between Physics and Mathematics

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
On the Concept of Time in Everyday Life and Between Physics and Mathematics Ergonomics International Journal ISSN: 2577-2953 MEDWIN PUBLISHERS Committed to Create Value for Researchers On the Concept of Time in Everyday Life and between Physics and Mathematics Paolo Di Sia* Conceptual Paper Department of Physics and Astronomy, University of Padova, Italy Volume 5 Issue 2 Received Date: March 03, 2021 *Corresponding author: Paolo Di Sia, Department of Physics & Astronomy, School of Science Published Date: March 16, 2021 and Medicine, University of Padova, Padova, Italy, Email: [email protected] DOI: 10.23880/eoij-16000268 Abstract In this paper I consider the concept of time in a general way as daily human time and then within physics with relation to mathematics. I consider the arrow of time and then focus the attention on quantum mechanics, with its particular peculiarities, examining important concepts like temporal asymmetry, complexity, decoherence, irreversibility, information theory, chaos theory. In conclusion I consider the notion of time connected to a new theory in progress, called “Primordial Dynamic Space” theory. Keywords: Time; Modern Physics; Irreversibility; Decoherence; Symmetry; Entanglement; Complexity; “Primordial Dynamic Space” Theory; Education Introduction the past that still lasts in the present and which exists in the The problem of time is one of the fundamental problems of human existence; even before being the subject of presentThe memoryrelation as between a transfigured the three past. dimensions of time philosophical investigation, it constitutes the man’s ever- involves another very important existential aspect: how present problem, since even in an unconscious way it to act so that a painful past no longer exists and so that a is intrinsically linked to our life. From the viewpoint of beloved present continues to exist and does not die in the existential philosophy, it also involves the problem of the past. destiny of man, considered only indirectly by mathematical and naturalist philosophy. It is in fact over time that the Time is for some aspects an evil and its passing can destiny of human existence is realized. be sad. This evil consists in the impossibility of savoring the present in all its fullness, due to the impossibility of A double meaning is linked to the concept of time: on completely freeing yourself by the sadness of the past and a hand we have the fear, the worry, which temporalize the the fear of the future. being, on the other hand the hope, the change produced by creative activity. This dualism is intrinsic in the structure of The joy of living the present moment as total fullness the person, in the sense of union between the changeable is always denied by the elapse of time. Without the loss of and the immutable. Time is therefore a change in two distinct many things of the past, the man should not be able to live; a meanings: as development of life and as death. total memory would destroy him. This need to forget the past denotes an evil of time. in the future; but this past and this future exist only in the The temporal dualism becomes evident in the present present.The man’sFurthermore, destiny theis fulfilledpast can in be time, considered in the past under and a moment. The instant can be seen as a small fraction of time, double aspect: the past that has existed and is now over, and an infinitesimal fraction between the past and the future; but On the Concept of Time in Everyday Life and between Physics and Mathematics Ergonomics Int J 2 Ergonomics International Journal we can also see it as not belonging to time, as instant that of time (differentiable time, time in different dimensions, cannot be divided into past and future. This problem has non-continuous time) and there are also time-independent evident links to our age, dominated by technology and by theories [4]. speed. The subjective time, as memory of every moment of The value of the instant is lost in it, which becomes the present of our consciousness, has an asymmetrical only a means for the following instant. Time becomes thus structure and is elastic. The past seems written, frozen; we an accelerated time, where the man is leaning towards the can remember it, but we can no longer hear that it runs. The future and his ego decomposes in this temporal speed, losing the unity that is instead deeply connected to the unity of the everyday life, past and future are not equivalent; there is a indivisible moment. relativefuture appears condition uncertain, due to our not consciousness. firmly attached to reality. In The time-man relation is for some aspects paradoxical: on a hand the person is change, realization over time, on the other hand she/he is immutability, unity through the change, and therefore is damaged by time. Time flows constantly, even if our perception of its increasingflow varies speed.according This to sensation our emotional is not state;actually when time, we itsay is Another fundamental problem closely connected with thethat differenttime runs way quickly, in which we imagine we emotionally something experience flowing at the an time is the problem of death. Death occurs in time, resides in running reality [5]. can consider two meanings: a quantitative and a qualitative To date, it has been not fully possible to demonstrate, on life and is its end. In the relation between time and infinity, we on the other hand, victory over death and healing from the future. The human being appeals to basic personal feelings, one. Time seen as quantitative infinite brings death with it; toa scientific the fact thatlevel, we that are time witnessing exists and our flows aging, from to the a pastfact thatto a time or eternity [1]. disorder, in a closed system, spontaneously grows [6]. evil of time is linked to the meaning of qualitative infinity of The intensity of our inner life can change the character The concept of arrows of time has been studied in of time; time that can accelerate or slow down in relation to the richness of life has no mathematical character [2]. the concepts of change and invariance, two contradictory but Two of man’s greatest problems, namely the problem of inseparablerelation to irreversibility. components Itin seemsthe human difficult effort to be to able understand to untie the foundation and the problem of the future, are both reality; it seems not possible to fully explain the change inseparably linked to time and reveal it as the intimate without referring to the invariance, and vice versa. destiny of man. The human existence is immersed in time; its origin and conclusion seem to go beyond it. Within physics and science in general, there are The notion of time is present in all areas of thought gravitational, biological arrows of time; each of them is different times, reflections on cosmological, thermodynamic, mathematics to physics, from philosophy to neurosciences. whether one is more fundamental than the others [7-9]. Thethat reflectproblem and of study time theescapes reality our and senses the human and mathematics being, from based on different principles, and it is difficult to determine and physics often lead to results that are logically far from Mathematics has been studied and used since ancient the ordinary human thinking. times; however, it is starting by Descartes, Galileo and Newton that the mathematical language has been elevated Mathematically, time is indicated as a variable t present to the rank of true language of Nature, allowing to talk about t phenomena and make predictions. instantin the equations;is in a one-to-one time flows correspondence and the term with definesa point ofsome this In some cases it is possible to create, starting by line.dynamics. When Timewe graphically can be defined represent on ana movementoriented line, in space, each differential equations with respect to time, solutions in which time is considered as if it were another spatial dimension. the parameter t is completely eliminated; as example, from This is a static way of interpreting time, there is also the the time-dependent solutions of Newton’s equations for an orbital motion, r(t) and α(t), one can build time-independent solutions r(α). The motions in the universe could be replaced dynamic way, related to the flow of time [3]. This is an interesting theme, because it demonstrates how theyIn are particle two different physics, conceptionsspace-time isof flat,time. rigid The and canonical static; theby timeless interpretation trajectories of the tin parameter a larger space can present of configurations. many more in general relativity it is curved, flexible and dynamic; aspects than we think, and also, in some sense, leads to the scientific theories developed to date use different notions Paolo Di Sia. On the Concept of Time in Everyday Life and between Physics and Mathematics. Copyright© Paolo Di Sia. Ergonomics Int J 2021, 5(2): 000268. 3 Ergonomics International Journal elimination of a generic absolute time. in which there are delayed and advanced solutions, The mathematized time of physics does not exhaust the sense • To the self-organization of matter, in physical and of lived time, not more than lived time gives the intuition of biologicalalthough only processes, the first oneswhich seem has to beenoccur inof Nature;enormous all aspects of physical time. The simplest scheme adopted by science consists of a homogeneous one-dimensional (1D) global entropy, when the surrounding environment is time, composed of instants that follow one by another in an considered,importance alwaysin Prigogine’s grows inreflections. harmony Itwith is knownthe second that identical way. According to the thinking of some authors, it law of thermodynamics, but in relation to the single would not grasp the essential nature of the duration of the system (for example a cell) we can witness an entropic true time of life, which is continuous invention, continuous decrease [13]; emergence of novelty [10].
Load more

Recommended publications
  • A Direction of Time in Time-Symmetric Electrodynamics
    COLUMBIA UNIVERSITY MASTER’S THESIS A Direction of Time in Time-Symmetric Electrodynamics Author: Supervisor: Kathleen TATEM Dr. Erick WEINBERG A thesis submitted in fulfillment of the requirements for the degree of Master of Arts in the Philosophical Foundations of Physics Graduate School of Arts and Sciences May 17, 2017 ii In grateful memory of my mentor, Dr. John M. J. Madey. iii Columbia University Abstract Departments of Physics and Philosophy Graduate School of Arts and Sciences Master of Arts A Direction of Time in Time-Symmetric Electrodynamics by Kathleen TATEM This thesis introduces a recent analytical verification which is of significance to the philosophical debate on the direction of time in the case of electromagnetic radiation. I give an overview of a the problem of the direction of time in thermodynamics, as well as how it is solved with the Past Hypothesis, a hypothesis that the macrostate of the universe at the moment of the Big Bang was an extremely low-entropy state. I also describe the standard accepted textbook solution to the radiation problem, as well as an alternative time-symmetric theory presented by Feynman and Wheeler that had historically been considered less favorable to physicists. Analytical ver- ification supports that time-symmetric accounts of radiation such as Feynman and Wheeler’s theory are needed for radiation fields to comply with energy conservation and the fundamental equations of electromagnetism. I describe two other philo- sophical accounts of the direction of time in radiation theory, and then argue that proposed experiments based on this recent analytical result can help us rule out some of the alternative philosophical proposals on the origin of the direction of time in radiation theory.
    [Show full text]
  • Time in Quantum Cosmology of FRW F(R) Theories
    galaxies Article Time in Quantum Cosmology of FRW f (R) Theories C. Ramírez 1,* ID and V. Vázquez-Báez 2 ID 1 Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Puebla 72570, Mexico 2 Facultad de Ingeniería, Benemérita Universidad Autónoma de Puebla, Puebla 72570, Mexico; [email protected] * Correspondence: [email protected]; Tel.: +52-222-229-5637 Received: 1 December 2017; Accepted: 9 January 2018; Published: 17 January 2018 Abstract: The time problem is a problem of canonical quantum gravity that has long been known about; it is related to the relativistic invariance and the consequent absence of an explicit time variable in the quantum equations. This fact complicates the interpretation of the wave function of the universe. Following proposals to assign the clock function to a scalar field, we look at the scalar degree of freedom contained in f (R) theories. For this purpose we consider a quadratic f (R) theory in an equivalent formulation with a scalar field, with a FRW metric, and consider its Wheeler-DeWitt equation. The wave function is obtained numerically and is consistent with the interpretation of the scalar field as time by means of a conditional probability, from which an effective time-dependent wave function follows. The evolution the scale factor is obtained by its mean value, and the quantum fluctuations are consistent with the Heisenberg relations and a classical universe today. Keywords: quantum cosmology; modified gravity; time problem 1. Introduction Since its formulation, general relativity has been a successful theory, verified in many ways and at any scale.
    [Show full text]
  • Quantum Geometrodynamics: Whence, Whither?
    Gen Relativ Gravit manuscript No. (will be inserted by the editor) Claus Kiefer Quantum Geometrodynamics: whence, whither? Received: date / Accepted: date Abstract Quantum geometrodynamics is canonical quantum gravity with the three-metric as the configuration variable. Its central equation is the Wheeler–DeWitt equation. Here I give an overview of the status of this ap- proach. The issues discussed include the problem of time, the relation to the covariant theory, the semiclassical approximation as well as applications to black holes and cosmology. I conclude that quantum geometrodynamics is still a viable approach and provides insights into both the conceptual and technical aspects of quantum gravity. Keywords Quantum gravity quantum cosmology black holes · · PACS 04.60.-m 04.60.Ds 04.62.+v · · These considerations reveal that the concepts of spacetime and time itself are not primary but secondary ideas in the structure of phys- ical theory. These concepts are valid in the classical approximation. However, they have neither meaning nor application under circum- stances when quantum-geometrodynamical effects become important. There is no spacetime, there is no time, there is no before, there is arXiv:0812.0295v1 [gr-qc] 1 Dec 2008 no after. The question what happens “next” is without meaning. (John A. Wheeler, Battelle Rencontres 1968) Dedicated to the memory of John Archibald Wheeler. Claus Kiefer Institut f¨ur Theoretische Physik, Universit¨at zu K¨oln, Z¨ulpicher Straße 77, 50937 K¨oln, Germany E-mail: [email protected] 2 1 Introduction The quantization of the gravitational field is still among the most important open problems in theoretical physics.
    [Show full text]
  • An Introduction to Loop Quantum Gravity with Application to Cosmology
    DEPARTMENT OF PHYSICS IMPERIAL COLLEGE LONDON MSC DISSERTATION An Introduction to Loop Quantum Gravity with Application to Cosmology Author: Supervisor: Wan Mohamad Husni Wan Mokhtar Prof. Jo~ao Magueijo September 2014 Submitted in partial fulfilment of the requirements for the degree of Master of Science of Imperial College London Abstract The development of a quantum theory of gravity has been ongoing in the theoretical physics community for about 80 years, yet it remains unsolved. In this dissertation, we review the loop quantum gravity approach and its application to cosmology, better known as loop quantum cosmology. In particular, we present the background formalism of the full theory together with its main result, namely the discreteness of space on the Planck scale. For its application to cosmology, we focus on the homogeneous isotropic universe with free massless scalar field. We present the kinematical structure and the features it shares with the full theory. Also, we review the way in which classical Big Bang singularity is avoided in this model. Specifically, the spectrum of the operator corresponding to the classical inverse scale factor is bounded from above, the quantum evolution is governed by a difference rather than a differential equation and the Big Bang is replaced by a Big Bounce. i Acknowledgement In the name of Allah, the Most Gracious, the Most Merciful. All praise be to Allah for giving me the opportunity to pursue my study of the fundamentals of nature. In particular, I am very grateful for the opportunity to explore loop quantum gravity and its application to cosmology for my MSc dissertation.
    [Show full text]
  • Machine Learning the Thermodynamic Arrow of Time
    ARTICLES https://doi.org/10.1038/s41567-020-1018-2 Machine learning the thermodynamic arrow of time Alireza Seif 1,2 ✉ , Mohammad Hafezi 1,2,3 and Christopher Jarzynski 1,4 The asymmetry in the flow of events that is expressed by the phrase ‘time’s arrow’ traces back to the second law of thermody- namics. In the microscopic regime, fluctuations prevent us from discerning the direction of time’s arrow with certainty. Here, we find that a machine learning algorithm that is trained to infer the direction of time’s arrow identifies entropy production as the relevant physical quantity in its decision-making process. Effectively, the algorithm rediscovers the fluctuation theorem as the underlying thermodynamic principle. Our results indicate that machine learning techniques can be used to study systems that are out of equilibrium, and ultimately to answer open questions and uncover physical principles in thermodynamics. he microscopic dynamics of physical systems are We first introduce the relevant physical laws that govern time-reversible, but the macroscopic world clearly does not microscopic, non-equilibrium fluctuations, and briefly review the Tshare this symmetry. When we are shown a movie of a mac- machine learning techniques that we will use. We then apply our roscopic process, we can typically guess easily whether the movie is methods to various model physical examples, and study the ability played in the correct order or in time-reversed order. In 1927, Sir of machine learning techniques to learn and quantify the direction Arthur Eddington coined the phrase ‘time’s arrow’ to express this of time’s arrow.
    [Show full text]
  • SPACE, TIME, and (How They) MATTER: a Discussion of Some Metaphysical Insights About the Nature of Space and Time Provided by Our Best Fundamental Physical Theories
    SPACE, TIME, AND (how they) MATTER: A Discussion of Some Metaphysical Insights about the Nature of Space and Time Provided by Our Best Fundamental Physical Theories Valia Allori Northern Illinois University Forthcoming in: J. Statchel, G.C. Ghirardi (eds.). Space, Time, and Frontiers of Human Understanding. Springer-Verlag Abstract This paper is a brief (and hopelessly incomplete) non-standard introduction to the philosophy of space and time. It is an introduction because I plan to give an overview of what I consider some of the main questions about space and time: Is space a substance over and above matter? How many dimensions does it have? Is space-time fundamental or emergent? Does time have a direction? Does time even exist? Nonetheless, this introduction is not standard because I conclude the discussion by presenting the material with an original spin, guided by a particular understanding of fundamental physical theories, the so-called primitive ontology approach. 1. Introduction Scientific realists believe that our best scientific theories could be used as reliable guides to understand what the world is like. First, they tell us about the nature of matter: for instance, matter can be made of particles, or two-dimensional strings, or continuous fields. In addition, whatever matter fundamentally is, it seems there is matter in space, which moves in time. The topic of this paper is what our best physical theories tell us about the nature of space and time. I will start in the next section with the traditional debate concerning the question of whether space is itself a substance or not.
    [Show full text]
  • A Local Resolution of the Problem of Time V
    A LOCAL RESOLUTION OF THE PROBLEM OF TIME V. Combining Temporal and Configurational Relationalism for Finite Theories E. Anderson based on calculations done at Peterhouse, Cambridge Abstract As we have known comprehensively since the early 1990’s works of Isham and Kuchař, The Problem of Time mostly concerns interferences between its many facets. Having introduced the local facets in Articles I to IV, we now show how Article I’s approach to Temporal Relationalism can be combined with Article II’s to Configurational Relationalism. This requires reformulating some of the Principles of Dynamics to be Temporal Relationalism implementing, a strategy which we follow through in each subsequent Article. All in all, around half of the Principles of Dynamics needs to be rewritten to solve this noted, 50-year-old and hitherto unresolved foundational problem. This stands as sufficient reason to render new resultant Principles of Dynamics – ‘TRiPoD’ – a significant and worthwhile development of the Principles of Dynamics. This amounts to taking Jacobi’s action principle more seriously than Jacobi himself did, or any authors in between: to constitute a new starting point for the entirety of the Principles of Dynamics is to be reworked. This can moreover be viewed as a mild recategorization necessitated by the Problem of Time. While mathematically simple to carry out, it requires quite a lot of conceptual developments, by which it is both prudent and useful exposition to present this first for finite rather than Field Theoretic examples in the current Article. Article VI then extends this approach to Field Theory and GR. 1 Introduction In this fifth Article on the Problem of Time [9, 10, 7, 15, 22, 23, 24, 29, 38, 39, 41, 44, 45, 50, 47, 51, 52, 53, 54, 55], we combine Article I’s Temporal Relationalism [1, 2, 16, 25, 39] and Article II’s Configurational Relationalism [1, 2, 16, 39] for Finite Theories.
    [Show full text]
  • Gravity and Gauge Theory∗
    Gravity and Gauge Theory∗ Steven Weinstein Department of Philosophy, Northwestern University Abstract Gauge theories are theories that are invariant under a characteristic group of “gauge” trans- formations. General relativity is invariant under transformations of the diffeomorphism group. This has prompted many philosophers and physicists to treat general relativity as a gauge theory, and diffeomorphisms as gauge transformations. I argue that this approach is misguided. The theories of three of the four fundamental interactions of nature are “gauge” theories. A central feature of such theories is their invariance under a group of local transformations, i.e., transformations which may vary from spacetime point to spacetime point. The characteristic group of these “gauge” transformations is called the “gauge group.” The theory of the fourth interaction, gravity, is general relativity. General relativity has its own invariance group, the diffeomorphism group. Insofar as one understands “gauge theory” to mean a theory in which “the physics” (more on the ambiguity of this term later) is invariant under a certain group of transformations, one might be tempted to construe general relativity as a gauge theory.1 Just such a construal Þgures in recent work of Belot (1996) and Belot & Earman (1999a,b), who follow many (but not all) physicists in treating the diffeomorphism group as a gauge group, and who draw implications for the “hole argument.”2 In this paper, I show that general relativity is not a gauge theory at all, in the speciÞc sense that “gauge theory” has in elementary particle physics. This issue is of crucial importance to attempts to quantize general relativity, because in quantum theory, the generators of gauge transformations are emphatically not treated as observables, while the generators of spatiotemporal (e.g., Lorentz) transformations are in fact the canonical observables.
    [Show full text]
  • Canonical Quantum Gravity and the Problem of Time
    Imperial/TP/91-92/25 Canonical Quantum Gravity and the Problem of Time 1 2 C.J. Isham Blackett Laboratory Imperial College South Kensington London SW7 2BZ United Kingdom August 1992 Abstract The aim of this paper is to provide a general introduction to the problem of time in quantum gravity. This problem originates in the fundamental conflict between arXiv:gr-qc/9210011v1 21 Oct 1992 the way the concept of ‘time’ is used in quantum theory, and the role it plays in a diffeomorphism-invariant theory like general relativity. Schemes for resolving this problem can be sub-divided into three main categories: (I) approaches in which time is identified before quantising; (II) approaches in which time is identified after quantising; and (III) approaches in which time plays no fundamental role at all. Ten different specific schemes are discussed in this paper which also contain an introduction to the relevant parts of the canonical decomposition of general relativity. 1Lectures presented at the NATO Advanced Study Institute “Recent Problems in Mathematical Physics”, Salamanca, June 15–27, 1992. 2Research supported in part by SERC grant GR/G60918. Contents 1 INTRODUCTION 4 1.1 Preamble ................................... 4 1.2 PreliminaryRemarks ............................. 4 1.3 Current Research Programmes in Quantum Gravity . ..... 6 1.4 OutlineofthePaper ............................. 8 1.5 Conventions.................................. 9 2 QUANTUMGRAVITYANDTHEPROBLEMOFTIME 9 2.1 Time in Conventional Quantum Theory . .. 10 2.2 Time in a Diff( )-invariantTheory . 12 M 2.3 ApproachestotheProblemofTime. 16 2.4 Technical Problems With Time . 19 3 CANONICALGENERALRELATIVITY 20 3.1 IntroductoryRemarks ............................ 21 3.2 Quantum Field Theory in a Curved Background .
    [Show full text]
  • The General Theory of Space Time, Mass, Energy, Quantum Gravity, Perception, Four Fundamental Forces, Vacuum Energy, Quantum Field
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by International Institute for Science, Technology and Education (IISTE): E-Journals Journal of Natural Sciences Research www.iiste.org ISSN 2224-3186 (Paper) ISSN 2225-0921 (Online) Vol.2, No.4, 2012 The General Theory of Space Time, Mass, Energy, Quantum Gravity, Perception, Four Fundamental Forces, Vacuum Energy, Quantum Field *1Dr K N Prasanna Kumar, 2Prof B S Kiranagi And 3Prof C S Bagewadi *1Dr K N Prasanna Kumar, Post doctoral researcher, Dr KNP Kumar has three PhD’s, one each in Mathematics, Economics and Political science and a D.Litt. in Political Science, Department of studies in Mathematics, Kuvempu University, Shimoga, Karnataka, India Correspondence Mail id : [email protected] 2Prof B S Kiranagi, UGC Emeritus Professor (Department of studies in Mathematics), Manasagangotri, University of Mysore, Karnataka, India 3Prof C S Bagewadi, Chairman , Department of studies in Mathematics and Computer science, Jnanasahyadri Kuvempu university, Shankarghatta, Shimoga district, Karnataka, India Abstract Essentially GUT and Vacuum Field are related to Quantum field where Quantum entanglement takes place. Mass energy equivalence and its relationship with Quantum Computing are discussed in various papers by the author. Here we finalize a paper on the relationship of GUT on one hand and space-time, mass-energy, Quantum Gravity and Vacuum field with Quantum Field. In fact, noise, discordant notes also are all related to subjective theory of Quantum Mechanics which is related to Quantum Entanglement and Quantum computing. Key words: Quantum Mechanics, Quantum computing, Quantum entanglement, vacuum energy Introduction: Physicists have always thought quantum computing is hard because quantum states are incredibly fragile.
    [Show full text]
  • 'Hole Argument' And
    Regarding the ‘Hole Argument’ and the ‘Problem of Time’ Sean Gryb and Karim P. Y. Thébault*y The canonical formalism of general relativity affords a particularly interesting charac- terization of the infamous hole argument. It also provides a natural formalism in which to relate the hole argument to the problem of time in classical and quantum gravity. Con- ceptual and formal inadequacies within the representative language of canonical gravity will be shown to be at the heart of both the canonical hole argument and the problem of time. Interesting and fruitful work at the interface of physics and philosophy relates to the challenge of resolving such inadequacies. 1. Introduction. The ‘hole argument’ is an interpretational dilemma in the foundations of general relativity. Although the argument originates with Einstein, the terms of the modern debate were set by Earman and Norton (1987).1 In essence, Earman and Norton argue that a certain view on the ontology of space-time (‘substantivalism’) leads to an underdetermination problem when pairs of solutions are connected by a certain subset of sym- Received December 2015; revised February 2015. *To contact the authors please write to: Sean Gryb, Institute for Mathematics, Astro- physics and Particle Physics, Radboud University, Nijmegen; e-mail: [email protected]. Karim P. Y. Thébault, Department of Philosophy, University of Bristol; e-mail: karim [email protected]. yWe are hugely indebted to Erik Curiel, Samuel Fletcher, Oliver Pooley, Bryan Roberts, and James Weatherall for discussion and written comments that were invaluable in the evolution of this article. We are also very appreciative of feedback from members of au- diences in Berlin, Bristol, London, and Oxford.
    [Show full text]
  • Quantum Gravity : Motivations and Alternatives 1
    Quantum Gravity : Motivations and Alternatives 1 Reiner Hedrich 2 Institut für Philosophie und Politikwissenschaft Fakultät Humanwissenschaften und Theologie Technische Universität Dortmund Emil-Figge-Strasse 50 44227 Dortmund Germany Zentrum für Philosophie und Grundlagen der Wissenschaft Justus-Liebig-Universität Giessen Otto-Behaghel-Strasse 10 C II 35394 Giessen Germany Abstract The mutual conceptual incompatibility between General Relativity and Quantum Mechanics / Quan- tum Field Theory is generally seen as the most essential motivation for the development of a theory of Quantum Gravity. It leads to the insight that, if gravity is a fundamental interaction and Quantum Mechanics is universally valid, the gravitational field will have to be quantized, not at least because of the inconsistency of semi-classical theories of gravity. The objective of a theory of Quantum Gravity would then be to identify the quantum properties and the quantum dynamics of the gravitational field. If this means to quantize General Relativity, the general-relativistic identification of the gravitational field with the spacetime metric has to be taken into account. The quantization has to be conceptually adequate, which means in particular that the resulting quantum theory has to be background-independ- ent. This can not be achieved by means of quantum field theoretical procedures. More sophisticated strategies, like those of Loop Quantum Gravity , have to be applied. One of the basic requirements for 1 Research for this paper was generously supported by the Fritz-Thyssen-Stiftung für Wissenschaftsförderung under the project Raumzeitkonzeptionen in der Quantengravitation . Thanks also to Brigitte Falkenburg! 2 Email: [email protected] & [email protected] 2 such a quantization strategy is that the resulting quantum theory has a classical limit that is (at least approximately, and up to the known phenomenology) identical to General Relativity.
    [Show full text]