Classical aspects of Hawking radiation verified in analogue gravity experiment

TL;DR

This study demonstrates classical Hawking radiation analogues in a water wave experiment, showing wave pair production, classical correlations, and a Boltzmann-distributed spectrum consistent with theoretical predictions.

Contribution

The paper provides experimental verification of classical Hawking radiation features using water wave analogues, including wave pair creation and spectral distribution analysis.

Findings

Wave pairs are observed in the experiment.

The spectra follow a Boltzmann distribution.

Wave conversion is classically correlated.

Abstract

There is an analogy between the propagation of fields on a curved spacetime and shallow water waves in an open channel flow. By placing a streamlined obstacle into an open channel flow we create a region of high velocity over the obstacle that can include wave horizons. Long (shallow water) waves propagating upstream towards this region are blocked and converted into short (deep water) waves. This is the analogue of the stimulated Hawking emission by a white hole (the time inverse of a black hole). The measurements of amplitudes of the converted waves demonstrate that they appear in pairs and are classically correlated; the spectra of the conversion process is described by a Boltzmann-distribution; and the Boltzmann-distribution is determined by the determined by the change in flow across the white hole horizon.