Realistic Observable in Background-Free Quantum Gravity: the Planck-Star Tunnelling-Time

Marios Christodoulou (1, 2, 3) , Carlo Rovelli (3, 2) , Simone Speziale (3, 2) , Ilya Vilensky (2, 3)

1 University of Cyprus = Université de Chypre
2 CPT - E4 Gravité quantique
3 CPT - Centre de Physique Théorique - UMR 7332

A gravitationally collapsed object can bounce-out from its horizon via a tunnelling process that violates the classical equations in a finite region. Since tunnelling is a non-perturbative phenomenon, it cannot be described in terms of quantum fluctuations around a classical solution and a background-free formulation of quantum gravity is needed to analyze it. Here we use Loop Quantum Gravity to compute the amplitude for this process, in a first approximation. The amplitude determines the tunnelling time as a function of the mass. This is the key information to evaluate the astrophysical relevance of this process. The calculation offers a template and a concrete example of how a background-free quantum theory of gravity can be used to compute a realistical observable quantity.

Domaines: Relativité Générale et Cosmologie Quantique [gr-qc]; Phénomènes cosmiques de haute energie [astro-ph.HE]

Marios Christodoulou, Carlo Rovelli, Simone Speziale, Ilya Vilensky. Realistic Observable in Background-Free Quantum Gravity: the Planck-Star Tunnelling-Time. Physical Review D, 2016, 94 (8). ⟨hal-01476559⟩