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On the canonical approach to quantum gravity
Physical Review D, 1982General relativity has the property that, under the natural projection mapping, the image of the constraint surface in the phase space is a proper subset of the configuration space. This feature is not shared by other field theories of direct physical interest such as the Yang-Mills theory, nor by constrained systems which have been modeled after ...
Abhay Ashtekar, Gary T. Horowitz
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Unimodular theory of canonical quantum gravity
Physical Review D, 1989Einstein's theory of gravity is reformulated so that the cosmological constant becomes an integration constant of the theory, rather than a "coupling" constant. However, in the Hamiltonian form of the theory, the Hamiltonian constraint is missing, while the usual momentum constraints are still present.
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1992
Dirac’s theory of constrained Hamiltonian systems is first described, discussing in detail primary and secondary constraints, first-class and second-class constraints, Dirac brackets, effective Hamiltonian, total Hamiltonian and extended Hamiltonian. On quantization, the operator versions of first-class constraints become supplementary conditions on ...
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Dirac’s theory of constrained Hamiltonian systems is first described, discussing in detail primary and secondary constraints, first-class and second-class constraints, Dirac brackets, effective Hamiltonian, total Hamiltonian and extended Hamiltonian. On quantization, the operator versions of first-class constraints become supplementary conditions on ...
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2017
Letting aside temporarily the possibility to unify all forces in a single consistent framework, a question one can ask oneself is whether quantum mechanics can resolve a particular singularity, such as the big bang or that inside a black hole.
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Letting aside temporarily the possibility to unify all forces in a single consistent framework, a question one can ask oneself is whether quantum mechanics can resolve a particular singularity, such as the big bang or that inside a black hole.
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A constraint on canonical quantum gravity?
Nature, 2003Gamma rays from the γ-ray burst (GRB) 021206 have been reported to be strongly linearly polarized1, with the estimated degree of polarization (80 ± 20%) being close to the absolute maximum of 100% — affording us the opportunity to constrain models of quantum gravity, which has had 1010 years to act on the photons as they travelled towards us.
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Time and complex numbers in canonical quantum gravity
Physical Review D, 1993It is noted that not only time but also the imaginary unit is absent from the Wheeler-DeWitt equation (WDE), the basic equation of canonical quantum gravity. This leads to a severe problem in an attempt to recover the time-dependent Schrodinger equation from the WDE. It is suggested that the problem will be solved if the WDE is actually complex and not
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Canonical Quantum Gravity on the Space of Vassiliev Invariants
International Journal of Theoretical Physics, 1999zbMATH Open Web Interface contents unavailable due to conflicting licenses.
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Canonical Quantum Gravity and Effective Theory
2009Effective actions provide a powerful way to understand low-energy, semiclassical or other regimes of quantum field theories. Although canonical quantum gravity theories, such as loop quantum gravity, are not directly accessible to the usual techniques of computing effective actions, equivalent methods to derive an effective Hamiltonian and effective ...
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Canonical Loop Quantum Gravity
This article presents a comprehensive and self-contained review of Loop Quantum Gravity (LQG), focusing on both its canonical (Hamiltonian) formulation and covariant (spin foam) path integral approach. Beginning with the reformulation of General Relativity using Ashtekar–Barbero variables, it systematically constructs the kinematical Hilbert space ...openaire +1 more source