Emergence of gravity from spinfoams

TL;DR

This paper demonstrates that a specific limit in spinfoam quantum gravity reproduces Einstein's classical equations, providing evidence for the correctness of the covariant quantization approach and revealing new quantum corrections related to spacetime discreteness.

Contribution

It identifies a double scaling limit in spinfoam models that yields classical gravity, highlighting the role of the Immirzi parameter and quantum corrections.

Findings

Reproduction of Einstein equations in a specific spinfoam limit

Discovery of new quantum corrections from spacetime discreteness

Evidence supporting the classical limit of covariant quantum gravity

Abstract

We find a nontrivial regime of spinfoam quantum gravity that reproduces classical Einstein equations. This is the double scaling limit of small Immirzi parameter (gamma), large spins (j) with physical area (gamma times j) constant. In addition to quantum corrections in the Planck constant, we find new corrections in the Immirzi parameter due to the quantum discreteness of spacetime. The result is a strong evidence that the spinfoam covariant quantization of general relativity possesses the correct classical limit.