title: Quantum nature of the big bang.
abstract: Some long-standing issues concerning the quantum nature of the big bang are resolved in the context of homogeneous isotropic models with a scalar field. Specifically, the known results on the resolution of the big-bang singularity in loop quantum cosmology are significantly extended as follows: (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.
authors.affiliation: Institute for Gravitational Physics and Geometry, Physics Department, The Pennsylvania State University, University Park, PA 16802, USA. ashtekar@gravity.psu.edu
authors.forename: Abhay
authors.initials: A
authors.lastname: Ashtekar
authors.forename: Tomasz
authors.initials: T
authors.lastname: Pawlowski
authors.forename: Parampreet
authors.initials: P
authors.lastname: Singh