On Wigner's clock and the detectability of spacetime foam with gravitational-wave interferometers

TL;DR

The paper defends previous claims that future gravitational-wave detectors could observe spacetime foam, addressing criticisms and clarifying the theoretical basis, including connections to the holographic principle.

Contribution

It clarifies the validity of using Wigner's clock in spacetime foam detectability estimates and counters recent criticisms, reinforcing the potential for experimental detection.

Findings

Critiques of the quantum uncertainty limit are flawed.

Spacetime foam may be detectable with advanced interferometers.

Connections to the holographic principle support the feasibility.

Abstract

A recent paper (gr-qc/9909017) criticizes our work on the structure of spacetime foam. Its authors argue that the quantum uncertainty limit for the position of the quantum clock in a gedanken timing experiment, obtained by Wigner and used by us, is based on unrealistic assumptions. Here we point out some flaws in their argument. We also discuss their other comments and some other issues related to our work, including a simple connection to the holographic principle. We see no reason to change our cautious optimism on the detectability of spacetime foam with future refinements of modern gravitational-wave interferometers like LIGO/VIRGO and LISA.