Physics meets philosophy at the Planck scale
Contemporary Theories in Quantum Gravity
Edited by Craig Callender
Edited by Nick Huggett
Publisher: Cambridge University Press
Print Publication Year: 2001
Online Publication Date:December 2009
Online ISBN:9780511612909
Hardback ISBN:9780521662802
Paperback ISBN:9780521664455
Chapter DOI: http://dx.doi.org/10.1017/CBO9780511612909.013
Subjects: History, Philosophy and Foundations of Physics, Quantum Physics, Quantum Information and Quantum Computation
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Introduction
‘The term “3-geometry” makes sense as well in quantum geometrodynamics as in classical theory. So does superspace. But space-time does not. Give a 3-geometry, and give its time rate of change. That is enough, under typical circumstances to fix the whole time-evolution of the geometry; enough in other words, to determine the entire four-dimensional space-time geometry, provided one is considering the problem in the context of classical physics. In the real world of quantum physics, however, one cannot give both a dynamic variable and its time-rate of change. The principle of complementarity forbids. Given the precise 3-geometry at one instant, one cannot also know at that instant the time-rate of change of the 3-geometry. … The uncertainty principle thus deprives one of any way whatsoever to predict, or even to give meaning to, “the deterministic classical history of space evolving in time”. No prediction of spacetime, therefore no meaning for spacetime, is the verdict of the quantum principle’.
(Misner, Thorne, and Wheeler 1973)
One of the few propositions about quantum gravity that most physicists in the field would agree upon, that our notion of spacetime must, at best, be altered considerably in any theory conjoining the basic principles of quantum mechanics with those of general relativity, will be questioned in this chapter. We will argue, in fact, that most, if not all, of the conceptual problems in quantum gravity arise from the sort of thinking on display in the preceding quotation.
pp. i-vi
pp. vii-viii
pp. ix-x
pp. 1-30
Part I - Theories of Quantum Gravity and their Philosophical Dimensions : Read PDF
pp. 31-32
2 - Spacetime and the philosophical challenge of quantum gravity : Read PDF
pp. 33-89
3 - Naive quantum gravity : Read PDF
pp. 90-100
4 - Quantum spacetime: What do we know? : Read PDF
pp. 101-122
pp. 123-124
5 - Reflections on the fate of spacetime : Read PDF
pp. 125-137
6 - A philosopher looks at string theory : Read PDF
pp. 138-151
7 - Black holes, dumb holes, and entropy : Read PDF
pp. 152-174
Part III - Topological Quantum Field Theory : Read PDF
pp. 175-176
8 - Higher-dimensional algebra and Planck scale physics : Read PDF
pp. 177-196
Part IV - Quantum Gravity and the Interpretation of General Relativity : Read PDF
pp. 197-198
9 - On general covariance and best matching : Read PDF
pp. 199-212
10 - Pre-Socratic quantum gravity : Read PDF
pp. 213-255
11 - The origin of the spacetime metric: Bell's ‘Lorentzian pedagogy’ and its significance in general relativity : Read PDF
pp. 256-272
Part V - Quantum Gravity and the Interpretation of Quantum Mechanics : Read PDF
pp. 273-274
12 - Quantum spacetime without observers: Ontological clarity and the conceptual foundations of quantum gravity : Read PDF
pp. 275-289
13 - On gravity's role in quantum state reduction : Read PDF
pp. 290-304
14 - Why the quantum must yield to gravity : Read PDF
pp. 305-338
pp. 339-356
Notes on contributors : Read PDF
pp. 357-360
pp. 361-365