The Quantum Vacuum
A Scientific and Philosophical Concept, from Electrodynamics to String Theory and the Geometry of the Microscopic World
Publication Year: 2011
Published by: The Johns Hopkins University Press
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For useful comments and stimulating conversations on many of the topics addressed in the present work, I would like to thank Sergio Albeverio, Sisir Roy, Ernesto Carafoli, Giuseppe O. Longo, Antonio Saggion, Gabriele Veneziano, Ugo Bruzzo, Salvatore Califano, and Arthur Miller....
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Answers to some of the long- standing issues in twentieth- century theoretical physics, such as the cosmic singularity, the black matter, and energy, appear to be closely related to the problem of the quantum vacuum and its fluctuations. The properties of the universe arise from “nothing,” but this nothing is the quantum vacuum, which is a very...
Chapter 1 Introduction: The Vacuum as a Scientific and Philosophical Concept
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A vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is far, far less than standard atmospheric pressure. The root of the word vacuum is the Latin adjective vacuus, which means “empty,” but space can never be perfectly empty...
Chapter 2 The Role of Vacuum in Modern Physics
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The vacuum is fast emerging as the central structure of modern physics. This issue is especially important in the context of classical gravity, quantum electro-dynamics, and the grand unification program. The vacuum emerges as the syn-thesis of concepts of space, time, and matter; in the context of relativity and the quantum world, this new synthesis represents a structure of the most intricate ...
Chapter 3 The Quantum Vacuum in the Early Universe
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Quantum mechanics was never ignored in the development of cosmology. The properties of matter and radiation, spectral lines, light scattering, the statistics of Bose or Fermi— all these topics were taken into account in the calculation of pressure, energy density, spectrum transport...
Chapter 4 The Problem of the Vacuum and the Conceptual Conflict between General Relativity Theory and Quantum Mechanics
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According to Einstein and his special theory of relativity (STR), the ether does not exist at all. The electromagnetic fields are not states of a medium, but are independent realities not reducible to anything else. This conception suggests itself the more readily as electromagnetic...
Chapter 5 Topology and Curvature as Sources of Vacuum Fields
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In this chapter we investigate how the topological properties of space- time could influence the physical presence of field energy and particles matter in the physical vacuum. The “physical...
Chapter 6 The Dirac “Full-of-Particles Sea” Idea and the Vacuum in Quantum Field Theory
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The tendency of the wave function in nonrelativistic quantum mechanics to produce so many interpretations has been one of the most important theoretical problems of quantum field theory (QFT). Certain difficulties demonstrated that the classical field was not an appropriate...
Chapter 7 The Role of the Vacuum in Quantum Electrodynamics, the Casimir Effect, and Vacuum Polarization
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Relativistic quantum field theory, as exemplified by quantum electrodynamics (QED), makes a very clear distinction between what we would intuitively under-stand to be an absolute void and what we experience as the vacuum of space. After all, even in the deepest reaches of space we will find an atom or molecule here and there, and photons of energy are flying through continuously at the ...
Chapter 8 Hole Theory, Negative Energy Solutions, and Vacuum Fluctuations
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Notwithstanding the successes of the Dirac equation, we must face the interpretation of negative energy solutions. Their presence is difficult to accept, since in the final analysis they make all positive energy states unstable. A solution was proposed by Dirac as early as...
Chapter 9 Further Theoretical Remarks on the Vacuum Fluctuations: Poincar� Conformal Invariance and Spontaneous Symmetry-Breaking Symmetry
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In modern physics, the classical vacuum of still nothingness has been replaced by a quantum vacuum with fluctuations of measurable consequence. In fact, when we think about the vacuum in classical physics (say, in classical mechanics), we think of empty space unoccupied...
Chapter 10 More Intuitive Remarks on the Casimir Effect and Force, and on Their Significance
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Quantum mechanics was one of the most outstanding physical theories of the twentieth century. The other was the general theory of relativity. Quantum mechanics revealed nature at the microscopic scale as a strange and fascinating scientific object that seems to defy the natural human intuition developed through our everyday experience. Though this quantum character is present everywhere as the ...
Chapter 11 Dynamical Principles of Invariance and the Physical Interactions
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Intuitively, a symmetry principle is a statement that the laws of nature continue to look the same when we change our point of view in some way. The special principle of relativity says that the laws of nature appear the same to observers moving with any constant velocity. There are other space- time symmetries, some of them telling us that the laws of nature look the same when we rotate ...
Chapter 12 Quantum Electrodynamics and Gauge Theory
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In this chapter I want to emphasize some facts about quantum electrodynamics, that is, the theory that results from combining electron matter fields with electromagnetic fields— as first formulated in the 1930s by P. Dirac and essentially completed by about 1969 by S. Tomonaga (1968), J. Schwinger (1968), R. P. Feynman (1967), and F. J. Dyson (1949, 1969). We recall first that the theory is based on a local gauge symmetry....
Chapter 13 Vacuum as the Source of Asymmetry
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In this chapter we examine the relationship between the properties of the quantum vacuum and the breaking- symmetry phenomenon. In particular, we study the mechanism responsible for breaking the electroweak gauge symmetry, giving mass to the W and Z bosons. Is there a connection between these broken symmetries and the quantum vacuum low- energy of scalar particles and fields ...
Chapter 14 Topological Quantum Field Theories and Gauge Theories: A Far-Reaching Interface between Geometry and Physics
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It is well known that in quantum mechanics, the position and velocity of a particle are noncommuting operators acting on a Hilbert space, and classical notions such as “the trajectory of a particle” do not apply. But in nineteenth- and early twentieth-century physics, many aspects of nature were described in terms of fields— the electric...
Chapter 15 Remarks on Kaluza-Klein Theory and Supergravity
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In the 1920s there were the very interesting attempts by Theodor Kaluza, then by Oskar Klein, to unify the relativistic theory of gravitation with Maxwell’s theory by introducing a new geometrical framework within which electromagnetism could be coupled with gravity (at least theoretically). The Kaluza-Klein theories, purely geometrical in character, have been worked out in order to...
Chapter 16 Creation of Universes from Nothing
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The standard hot cosmological model of the universe gives a successful description of many features of its evolution. But the model is not totally satisfactory, for it requires that the Big Bang be preceded by rather unnatural initial conditions. One has to postulate that the universe began in a homogeneous and isotropic state with tiny density fluctuations that would evolve into galaxies. Homogeneity ...
Chapter 17 String Landscape and Vacuum Energy: The Emergence of a Multidimensional World from Geometrical Possibilities
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Let us examine in more detail the concluding idea of chapter 16. One possible starting point of the string picture is that the solution to Einstein’s field equations (roughly speaking, they say that matter tells space- time how to curve, and space- time tells matter how to move) is not unique, and many different geometries are therefore allowed. The case of 5- dimensional Kaluza-Klein geometry ...
Chapter 18 Concluding Remarks
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In these chapters, I have tried to stress the point that relativistic quantum field theory makes a very clear distinction between what we would intuitively under-stand to be an absolute void and what we experience as the vacuum of space. And as we had occasion to remark, even in the deepest reaches of space we will find an atom or molecule here or there, and photons of energy flying through...
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Page Count: 256
Illustrations: 5 halftones, 40 line drawings
Publication Year: 2011