Answers are grounded in this paper and cite their sources.
The conversion of positive-frequency waves into negative-frequency waves at the event horizon is the mechanism at the heart of the Hawking radiation of black holes. In black-hole analogues, horizons are formed for waves propagating in a medium against the current when and where the flow exceeds the wave velocity. We report on the first direct observation of negative-frequency waves converted from positive-frequency waves in a moving medium. The measured degree of mode conversion is significantly higher than that expected from the theory.
No takes yet. Share an insight, caveat, or question.
Rousseaux et al. (2008) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: