Is the Copenhagen Interpretation Inapplicable to Quantum Cosmology?

Shestakova, T. P.

doi:10.3390/universe6090128

Cited by 6 publications

(6 citation statements)

References 45 publications

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“…In the Wheeler-DeWitt approach, the lapse and shift functions, being gauge (non-physical) degrees of freedom, are believed to be irrelevant. However, it means the destruction of spacetime in quantum geometrodynamics (see [38] for a detailed discussion). The wave function of the Universe is declared to be not depending on the lapse and shift functions, which fix a reference frame.…”

Section: Discussionmentioning

confidence: 99%

The Birth of the Universe as a Result of the Change of the Metric Signature

Shestakova

2022

Physics

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In this paper, I discuss the idea that the birth of our Universe may be a result of a quantum transition from a physical continuum with the Euclidean signature to a Lorentzian spacetime. A similar idea was expressed by Andrei D. Sakharov At the classical level, the idea was studied by George F. R. Ellis and his collaborators, who explored if solutions to the classical Einstein equation exist which admit a change of metric signature. The present paper aims at examining possible realizations of this idea at the level of quantum gravity, in the framework of the Wheeler–DeWitt theory and in the extended phase space approach to quantization of gravity. I intend to answer the questions: to answer the questions: Does the Hartle–Hawking wave function imply such a realization? How can this idea be realized in the extended phase space approach to quantum gravity, where the change of signature is described by imposing special conditions on g00-component of the metric in different regions of the physical continuum? The conclusion is that the idea can be realized from a formal mathematical point of view, but it can hardly help in understanding how spacetime structure and time itself appeared from a timeless continuum.

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Section: Discussionmentioning

confidence: 99%

The Birth of the Universe as a Result of the Change of the Metric Signature

Shestakova

2022

Physics

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“…In the Wheeler -DeWitt approach, the lapse and shift functions, being gauge (nonphysical) degrees of freedom, are believed to be irrelevant. But it means the destruction of spacetime in quantum geometrodynamics (see a more detailed discussion in [38]). The wave function of the Universe is declared to be not depending on the lapse and shift functions, which fix a reference frame.…”

Section: Discussionmentioning

confidence: 99%

The birth of the Universe as a result of the change of the metric signature

Shestakova

2022

Preprint

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In this paper, I discuss the idea that the birth of our Universe may be a result of a quantum transition from a physical continuum with the Euclidean signature to a Lorentzian spacetime. A similar idea was expressed by Andrei D. Sakharov. At the classical level, the idea was studied by George F. R. Ellis and his collaborators, who explored if solutions to the classical Einstein equation exist which admit a change of metric signature. The present paper aims at examining possible realizations of this idea at the level of quantum gravity, in the framework of the Wheeler -DeWitt theory and in the extended phase space approach to quantization of gravity. I intend to answer the questions: Does the Hartle -Hawking wave function imply such a realization? How can this idea be realized in the extended phase space approach to quantum gravity, where the change of signature is described by imposing special conditions on g 00component of the metric in different regions of the physical continuum? The conclusion is that the idea can be realized from a formal mathematical point of view, but it can hardly help in understanding how spacetime structure and time itself appeared from a timeless continuum.

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“…An explanation that one can find in the literature suggests validity of a semiclassical approximation to quantum gravity that leads to an approximate Schrödinger equation of non-gravitational fields with respect to the semiclassical background (see, for example, [30]). However making use of the semiclassical approximation implies that a classical spacetime has already come into being [31].…”

Section: Time Coordinates and Evolution In Timementioning

confidence: 99%

On A. D. Sakharov’s Hypothesis of Cosmological Transitions with Changes in the Signature of the Metric

Shestakova

2021

Universe

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The paper discusses possible consequences of A. D. Sakharov’s hypothesis of cosmological transitions with changes in the signature of the metric, based on the path integral approach. This hypothesis raises a number of mathematical and philosophical questions. Mathematical questions concern the definition of the path integral to include integration over spacetime regions with different signatures of the metric. One possible way to describe the changes in the signature is to admit time and space coordinates to be purely imaginary. It may look like a generalization of what we have in the case of pseudo-Riemannian manifolds with a non-trivial topology. The signature in these regions can be fixed by special gauge conditions on components of the metric tensor. The problem is what boundary conditions should be imposed on the boundaries of these regions and how they should be taken into account in the definition of the path integral. The philosophical question is what distinguishes the time coordinate among other coordinates but the sign of the corresponding principal value of the metric tensor. In particular, there is an attempt in speculating how the existence of the regions with different signature can affect the evolution of the Universe.

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Is the Copenhagen Interpretation Inapplicable to Quantum Cosmology?

Cited by 6 publications

References 45 publications

The Birth of the Universe as a Result of the Change of the Metric Signature

The Birth of the Universe as a Result of the Change of the Metric Signature

The birth of the Universe as a result of the change of the metric signature

On A. D. Sakharov’s Hypothesis of Cosmological Transitions with Changes in the Signature of the Metric

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