Remarkably, in 2007 Rousseaux et al.  reported the first direct observation of negative-frequency waves, converted from positive-frequency waves in a moving medium, albeit the degree of mode conversion appears to be significantly higher than that expected from theory. The same group has now set up a more compact experiment based on the hydraulic jump, wherein measurements of the “Froude cones” convincingly demonstrate the presence of a surface-wave white hole , (as described in Sections 4.1.3 and 4.1.4 and possibly implicit in the results of Badulin et al. ).
A related experiment, with a smaller water basin, performed under the auspices of the gravitation theory group (Physics) and the fluid mechanics group (Civil Engineering) at the University of British Columbia, has recently (August 2010) reported the detection of stimulated Hawking emission . This stimulated Hawking emission is a classical effect that (via the usual discussion in terms of Einstein and coefficients) is rather closely related to spontaneous quantum Hawking emission. A central result of the Weinfurtner et al. group is that the relevant Bogoliubov coefficients have been experimentally measured and are observed to satisfy the expected Boltzmann relation, and additional details will soon be available in planned follow-up articles.
Living Rev. Relativity 14, (2011), 3
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