Hawking predicted that black holes should radiate thermal radiation, the temperature being a function solely of the geometry near the horizon of the black hole. The same arguments show that one would also expect thermal radiation from other horizons, like the sonic horizon formed in a trans-sonic flow, or the horizon to fluid surface gravity waves formed by a blocking flow. This talk will discuss the phenomenon of black hole thermal emission, problems with its derivation, the ubiquity of such thermal emission by horizons, and the measurements made in the past year of the thermal spectrum of such radiation from a horizon for surface water waves in a flume.
Mot(s) clés libre(s) : Black holes, Hawking, Gravity

Combining the principles of general relativity and quantum theory still remains as elusive as ever. Recent work, that concentrated on the points of conflict and contact between quantum theory and general relativity, suggests a new perspective on gravity. It appears that the field equations of gravity in a wide class of theories - including, but not limited to, standard Einstein's theory - can be given a purely thermodynamic interpretation. In this approach gravity appears as an emergent phenomenon, like e.g., gas or fluid dynamics. I will describe the necessary background, key results, and their implications.
Mot(s) clés libre(s) : Gravity, General Relativity, Quantum Theory