Quantum nature of the big bang: An analytical and numerical investigation

By Abhay Ashtekar, T. Pawłowski, Parampreet Singh. 2006

567 citations recorded by the source corpus.

Analytical and numerical methods are developed to analyze the quantum nature of the big bang in the setting of loop quantum cosmology. They enable one to explore the effects of quantum geometry both on the gravitational and matter sectors and significantly extend the known results on the resolution of the big bang singularity. Specifically, the following results are established for the homogeneous isotropic model with a massless scalar field: (i) the scalar field is shown to serve as an internal clock, thereby providing a detailed realization of the 'emergent time' idea; (ii) the physical Hilbert space, Dirac observables, and semiclassical states are constructed rigorously; (iii) the Hamiltonian constraint is solved numerically to show that the big bang is replaced by a big bounce. Thanks to the nonperturbative, background independent methods, unlike in other approaches the quantum evolution is deterministic across the deep Planck regime. Our constructions also provide a conceptual framework and technical tools which can be used in more general models. In this sense, they provide foundations for analyzing physical issues associated with the Planck regime of loop quantum cosmology as a whole.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/661f706f00a0095842d5716b6b86a6b3bc4998b9

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Nuclear and High Energy Physics

In Statistical and Nonlinear Physics

Citations in the corpus

FUNDAMENTAL STRUCTURE OF LOOP QUANTUM GRAVITY (2005, methodology): “tly, semiclassical states are used to understand the quantum evolution of the universe across the deep Planck regime [29]. It turns out that the classical big bang is replaced by a quantum big bounce [30][31]. The predictions from loop quantum cosmology are reliable in the sense that the quantum dyn”
Introduction to Loop Quantum Cosmology (2011, methodology): “After the early papers by Bojowald, the kinematic structure of LQC was revised and more rigorously established [9], which made it possible to complete the quantization of the model in presence of a homogeneous massless scalar field minimally coupled to the geometry, as well as to study the resulting”
Loop Quantum Cosmology (2005, background): “However, the situation is not fully clarified since the original versions, where the magnitudes of higher power and inverse volume corrections were compared numerically [26, 27, 28], were based on formulations of isotropic loop quantum cosmology, where inverse volume corrections are artificially sup”
Towards spinfoam cosmology (2010, background): “[44] Abhay Ashtekar, Tomasz Pawlowski, and Parampreet Singh.”
Anomaly freedom in perturbative loop quantum gravity (2008, background): “(The latter is itself subject to the coordinate changes by transformations generated by the constraints.)”
Quantum extension of the Kruskal spacetime (2018, unknown): “Similarly, the μ̄-dynamics in homogeneous isotropic LQC was introduced by using well-motivated choices [20] but initially it was far from being clear that there aren’t other viable choices as well.”
Loop quantum cosmology: an overview (2008, methodology): “Secondly, in the μ̄ scheme, ∆lPl was at first taken to be the lowest non-zero eigenvalue 2 √ 3πγlPl [20, 23, 33, 48] (where γ is the Barbero-Immirzi parameter).”
The pre-inflationary dynamics of loop quantum cosmology: confronting quantum gravity with observations (2012, methodology): “A careful analysis [58–60] of constrained systems implies that the physical Hilbert space Ho is spanned by states that satisfy a mathematically ‘sharper’ Hamiltonian constraint, which can be intuitively thought of as the ‘positive frequency square-root’ of Ŝo o = 0 [23]: −i ∂φ o(ν, φ) = Ĥo o(ν, φ) (”
Loop quantization of the Schwarzschild interior revisited (2015, methodology): “black hole interior [6], the strategy followed a particular quantization of isotropic FLRW models [11, 12].”
Loop quantum cosmology of Bianchi I models (2009, background): “That they do was first shown by numerical simulations of the exact quantum equations [9, 10] in the k=0, Λ=0 case.”
Extension of the quantum theory of cosmological perturbations to the Planck era (2012, background): “Then, in the Schrödinger representation, one can introduce ‘coherent states’ Ψo(ν, φo) in Ho phy which are sharply peaked at γo [12].”