Quantum Nature of the Big Bang: Improved dynamics

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

1,041 citations recorded by the source corpus.

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. The scalar field continues to serve as ''emergent time'', the big bang is again replaced by a quantum bounce, and quantum evolution remains deterministic across the deep Planck regime. However, while with the Hamiltonian constraint used so far in loop quantum cosmology the quantum bounce can occur even at low matter densities, with the new Hamiltonian constraint it occurs only at a Planck-scale density. Thus, the new quantum dynamics retains the attractive features of current evolutions in loop quantum cosmology but, at the same time, cures their main weakness.

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

View Paper: https://www.semanticscholar.org/paper/94aade0b0e04ec92e659333516b34d53a477757a

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Citations in the corpus

Anomaly freedom in perturbative loop quantum gravity (2008, background): “This behavior is indeed well-motivated based on lattice refinements (where the physical vertex density is constant) and was introduced in [61] based on scaling arguments.”
The pre-inflationary dynamics of loop quantum cosmology: confronting quantum gravity with observations (2012, background): “Mathematically as well as physically, the deparametrization procedure outlined above is straightforward in the case when the scalar field potential V (φ) vanishes (for details, see [7, 23, 24]).”
The matter bounce scenario in loop quantum cosmology (2012, background): “, sharply peaked around a classical solution at late times), there exist a set of effective equations that provide an excellent approximation to the full quantum dynamics of the states at all times, even during the bounce [8, 9].”
Loop quantum cosmology: a status report (2011, methodology): “Therefore, the framework enables us to ask and answer physical questions such as: How do the expectation value of (or fluctuations in) the volume or matter density operator evolve with φ? These questions were first analyzed in detail by starting with a unit lapse in the classical theory (so that the”
Quantum extension of the Kruskal spacetime (2018, positive): “In FLRW models, limitations of the μo scheme were overcome through the so-called μ̄ scheme [22].”
Loop quantum dynamics of the Schwarzschild interior (2007, background): “An improved quantization of loop quantum cosmology whereby the parameter is assumed to explicitly depend on the scale factor has been applied in [5] and leads to the correct semi-classical behavior as well as more physically sensible quantum corrections to the standard cosmological dynamics.”