On the Ground State of Quantum Gravity

TL;DR

This paper proposes that the ground state of quantum gravity is best described by a space-time filled with a gas of Planck-scale wormholes, supporting Wheeler's quantum foam model.

Contribution

It introduces a variational calculation showing that quantum fluctuations favor a wormhole gas over flat space as the quantum gravity ground state.

Findings

Quantum gravity favors a wormhole gas as the ground state.

Space-time can be modeled as a Planck lattice with wormholes.

Supports Wheeler's quantum foam hypothesis.

Abstract

In order to gain insight into the possible Ground State of Quantized Einstein's Gravity, we have devised a variational calculation of the energy of the quantum gravitational field in an open space, as measured by an asymptotic observer living in an asymptotically flat space-time. We find that for Quantum Gravity (QG) it is energetically favourable to perform its quantum fluctuations not upon flat space-time but around a ``gas'' of wormholes, whose size is the Planck length $a_p$ ($a_p\simeq 10^{-33}$cm). As a result, assuming such configuration to be a good approximation to the true Ground State of Quantum Gravity, space-time, the arena of physical reality, turns out to be well described by Wheeler's Quantum Foam and adequately modeled by a space-time lattice with lattice constant $a_p$, the Planck lattice.