Some implications of signature-change in cosmological models of loop quantum gravity

Journal Article · Sat Aug 01 00:00:00 EDT 2015 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2015/08/052· OSTI ID:22525498

Bojowald, Martin ^[1]; Mielczarek, Jakub ^[2]

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1. Institute for Gravitation and the Cosmos, The Pennsylvania State University, 104 Davey Lab, University Park, PA 16802 (United States)
2. Laboratoire de Physique Subatomique et de Cosmologie, UJF, INPG, CNRS, IN2P3 53, avenue des Martyrs, 38026 Grenoble cedex (France)

Signature change at high density has been obtained as a possible consequence of deformed space-time structures in models of loop quantum gravity. This article provides a conceptual discussion of implications for cosmological scenarios, based on an application of mathematical results for mixed-type partial differential equations (the Tricomi problem). While the effective equations from which signature change has been derived are shown to be locally regular and therefore reliable, the underlying theory of loop quantum gravity may face several global problems in its semiclassical solutions.

• OSTI ID: 22525498
• Journal Information: Journal of Cosmology and Astroparticle Physics, Vol. 2015, Issue 08; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
COSMOLOGICAL MODELS
DENSITY
LOOP QUANTUM GRAVITY
MATHEMATICAL SOLUTIONS
PARTIAL DIFFERENTIAL EQUATIONS
SEMICLASSICAL APPROXIMATION
SPACE-TIME