A Quantum-Gravity Perspective on Semiclassical vs. Strong-Quantum Duality

TL;DR

This paper demonstrates that the symmetry relating semiclassical and strong-quantum regimes in quantum gravity is equivalent to the exchange of long and short distances, establishing a fundamental length scale and classifying duality groups.

Contribution

It proves the equivalence between semiclassical/strong-quantum duality and long/short distance exchange, providing a framework to classify duality groups in quantum gravity.

Findings

Semiclassical vs. strong-quantum symmetry is equivalent to long-short distance exchange.

This symmetry enforces the existence of a fundamental length scale.

A classification scheme for duality groups in spacetime actions is developed.

Abstract

It has been argued that, underlying M-theoretic dualities, there should exist a symmetry relating the semiclassical and the strong-quantum regimes of a given action integral. On the other hand, a field-theoretic exchange between long and short distances (similar in nature to the T-duality of strings) has been shown to provide a starting point for quantum gravity, in that this exchange enforces the existence of a fundamental length scale on spacetime. In this letter we prove that the above semiclassical vs. strong-quantum symmetry is equivalent to the exchange of long and short distances. Hence the former symmetry, as much as the latter, also enforces the existence of a length scale. We apply these facts in order to classify all possible duality groups of a given action integral on spacetime, regardless of its specific nature and of its degrees of freedom.