Search for Quantum Gravity

TL;DR

This paper reviews theoretical approaches to quantum gravity and discusses potential experimental tests, suggesting that current and near-future observations could detect quantum space-time structures at the Planck scale.

Contribution

It provides an overview of quantum gravity theories and highlights feasible experimental tests using astrophysical and laboratory data to detect quantum space-time effects.

Findings

Current experiments are nearing sensitivity to Planck-scale effects.

Observations of distant astrophysical sources can test quantum gravity.

Laboratory experiments like kaon decays can probe quantum space-time.

Abstract

A satisfactory theory of quantum gravity may necessitate a drastic modification of our perception of space-time, by giving it a foamy structure at distances comparable to the Planck length. It is argued in this essay that the experimental detection of such structures may be a realistic possibility in the foreseeable future. After a brief review of different theoretical approaches to quantum gravity and the relationships between them, we discuss various possible experimental tests of the quantum nature of space-time. Observations of photons from distant astrophysical sources such as Gamma-Ray Bursters and laboratory experiments on neutral kaon decays may be sensitive to quantum-gravitational effects if they are only minimally suppressed. Experimental limits from the Whipple Observatory and the CPLEAR Collaboration are already probing close to the Planck scale, and significant increases in sensitivity are feasible.