Results 81 to 90 of about 37,871 (243)
Observational Constraints on Loop Quantum Cosmology
Physical Review Letters, 2011 In the inflationary scenario of loop quantum cosmology in the presence of inverse-volume corrections, we give analytic formulas for the power spectra of scalar and tensor perturbations convenient to compare with observations. Since inverse-volume corrections can provide strong contributions to the running spectral indices, inclusion of terms higher ...
Bojowald, M. +2 more
openaire +5 more sources
Restrictions on curved cosmologies in modified gravity from metric considerations
Physics Letters B, 2015 This study uses very simple symmetry and consistency considerations to put constraints on possible Friedmann equations for modified gravity models in curved spaces. As an example, it is applied to loop quantum cosmology.
Linda Linsefors, Aurelien Barrau
doaj +1 more source
Symmetry Reduction of Loop Quantum Gravity
, 2011 The relation between standard Loop Quantum Cosmology and full Loop Quantum Gravity fails already at the first nontrivial step: The configuration space of Loop Quantum Cosmology can not be embedded into the configuration space of full Loop Quantum Gravity
Brunnemann, Johannes, Koslowski, Tim A.
core +1 more source
Journal of Geophysical Research: Planets, Volume 130, Issue 7, July 2025.Abstract The geology of a potential Artemis landing site on Mons Malapert is examined using remote sensing techniques and lessons learned from Apollo missions to the lunar surface. Orthomosaics, digital terrain models, illumination models, thermal conditions, crater size‐frequency distribution analyses, geomorphological mapping, spectral and ...
David A. Kring +21 more
wiley +1 more source
Christian Bohr. Discoverer of Homotropic and Heterotopic Allostery
Acta Physiologica, Volume 241, Issue S734, July 2025.ABSTRACT This essay recounts and revisits the scientific contributions of Christian Bohr, highlighting his pivotal role in discovering allostery about 120 years ago. Bohr's meticulous experimentation led to identifying two distinct forms of allostery: homotropic (single‐ligand) and heterotropic (multi‐ligand), the latter widely recognized as the Bohr ...
Niels Bindslev
wiley +1 more source
New Hamiltonian constraint operator for loop quantum gravity
Physics Letters B, 2015 A new symmetric Hamiltonian constraint operator is proposed for loop quantum gravity, which is well defined in the Hilbert space of diffeomorphism invariant states up to non-planar vertices with valence higher than three. It inherits the advantage of the
Jinsong Yang, Yongge Ma
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The picture of the Bianchi I model via gauge fixing in Loop Quantum Gravity
, 2012 The implications of the SU(2) gauge fixing associated with the choice of invariant triads in Loop Quantum Cosmology are discussed for a Bianchi I model.
A. Marchini +16 more
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Mimicking Symmetry‐Breaking Einstein Ring by Optical Lens
Advanced Photonics Research, Volume 6, Issue 6, June 2025.This article uses an optical lens to emulate the gravitational lensing effect and observe the Einstein ring (ER) patterns. The symmetry‐breaking ER, i.e., Einstein cross, is observed utilizing a rotation‐symmetry‐breaking hemi‐ellipsoid lens. Deformed Einstein cross patterns induced by noncollinearly alignment of the light source–lens–observer are ...
Jun‐Liang Duan +5 more
wiley +1 more source
Critical Evaluation of Common Claims in Loop Quantum Cosmology
Universe, 2020 A large number of models have been analyzed in loop quantum cosmology, using mainly minisuperspace constructions and perturbations. At the same time, general physics principles from effective field theory and covariance have often been ignored.
Martin Bojowald
doaj +1 more source
Quantum Nature of the Big Bang: Improved dynamics [PDF]
, 2006 An improved Hamiltonian constraint operator is introduced in loop quantum cosmology. Quantum dynamics of the spatially flat, isotropic model with a massless scalar field is then studied in detail using analytical and numerical methods.
A. Ashtekar +11 more
core +3 more sources