We observe a thermal distribution of Hawking radiation, stimulated by quantum
vacuum fluctuations, emanating from an analogue black hole. This confirms
Hawking's prediction regarding black hole thermodynamics. The thermal
distribution is accompanied by correlations between the Hawking particles
outside the black hole and the partner particles inside. We find that the high
energy pairs of Hawking and partner particles are entangled, while the low
energy pairs are not. This has implications for the problem of information loss
in a black hole. The observation of Hawking radiation reported here verifies
Hawking's semiclassical calculation, which is viewed as a milestone in the
quest for quantum gravity.