Results 111 to 120 of about 1,549,437 (171)

Further results on geometric operators in quantum gravity [PDF]

, 1996
We investigate some properties of geometric operators in canonical quantum gravity in the connection approach `a la Ashtekar, which are associated with volume, area and length of spatial regions.
Loll, Renate, Loll, R.
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A First Class Constraint Generates Not a Gauge Transformation, But a Bad Physical Change: The Case of Electromagnetism [PDF]

, 2013
In Dirac-Bergmann constrained dynamics, a first-class constraint typically does not _alone_ generate a gauge transformation. By direct calculation it is found that each first-class constraint in Maxwell's theory generates a change in the electric field ...
Pitts, J. Brian, J. Brian Pitts
core   +2 more sources

Symplectic Structure of Intrinsic Time Gravity

Universe, 2016
The Poisson structure of intrinsic time gravity is analysed. With the starting point comprising a unimodular three-metric with traceless momentum, a trace-induced anomaly results upon quantization.
Eyo Eyo Ita, Amos S. Kubeka
doaj   +1 more source

Non-perturbative 3d Lorentzian quantum gravity [PDF]

, 2001
We have recently introduced a discrete model of Lorentzian quantum gravity, given as a regularized non-perturbative state sum over simplicial Lorentzian spacetimes, each possessing a uniqueWick rotation to Euclidean signature.
Ambj¢rn, J., Ambjørn, J., Loll, Renate, Ambjörn, Jan, Jurkiewicz, J., Dep Natuurkunde, Ambjørn, Jan, Quantum Gravity, Strings and Elementary Particles, Ambjörn, J., Jurkiewicz, Jerzy, Loll, R., Universiteit Utrecht   +11 more
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String Theory – Nomological Unification and the Epicycles of the Quantum Field Theory Paradigm [PDF]

, 2011
String Theory is the result of the conjunction of three conceptually independent elements: (i) the metaphysical idea of a nomological unity of the forces, (ii) the model-theoretical paradigm of Quantum Field Theory, and (iii) the conflict resulting from ...
Hedrich, Reiner
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Tunnelling to holographic traversable wormholes

SciPost Physics
We study nonperturbative effects of quantum gravity in a system consisting of a coupled pair of holographic CFTs. The AdS$_4$/CFT$_3$ system has three possible ground states: two copies of empty AdS, a pair of extremal AdS black holes, and an eternal AdS
Suzanne Bintanja, Ben Freivogel, Andrew Rolph
doaj   +1 more source

From Timeless Physical Theories to Timelessness

Humana.Mente: Journal of Philosophical Studies, 2018
This paper addresses the extent to which both Julian Barbour‘s Machian formulation of general relativity and his interpretation of canonical quantum gravity can be called timeless. We differentiate two types of timelessness in Barbour‘s (1994a, 1994b and
Samuel Baron, Peter Evans, Kristie Miller   +2 more
doaj  

Emergent Time and Time Travel in Quantum Physics

Universe
Entertaining the possibility of time travel will invariably challenge dearly-held concepts in fundamental physics. It becomes relatively easy to construct multiple logical contradictions using differing starting points from various well-established ...
Ana Alonso-Serrano, Sebastian Schuster, Matt Visser   +2 more
doaj   +1 more source

A quantum theory of gravity

European Physical Journal C: Particles and Fields
We develop a covariant Hamiltonian formalism in which evolution is measured along the proper-time flow of an observer congruence, replacing the external coordinate-time derivative with the Lie derivative. Our formalism keeps the Hamiltonian split between
Antonio Peña Peña
doaj   +1 more source

Emergent spacetime and empirical (in)coherence [PDF]

, 2012
Numerous approaches to a quantum theory of gravity posit fundamental ontologies that exclude spacetime, either partially or wholly. This situation raises deep questions about how such theories could relate to the empirical realm, since arguably only ...
Wuthrich, Christian, Huggett, Nick, Nick Huggett   +2 more
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