Nonequilibrium issues in macroscopic experiments

Gravitational wave ( G W) detectors are macroscopic instruments with displacement sensitivity approaching the limit set by the uncertainty principle. To this end, reducing the thermal noise down to negligible levels is often a major challenge to the experimentalists. Moreover , making a detect or with noise of pure stationary Gaussian statistics has proven to be as difficult as making a very sensitive one, these two requirements often being contrasting. From the thermodynamic viewpoint , G W experiments are usually modeled as equilibrium systems, but it is doubtful that this description is justified. We discuss the potential impact of non-equilibrium statistics on the performance of G W detectors. We also outline the research plan of the RareNoise project , which addresses this issue, and show so me experimental results on non-equilibrium macroscopic oscillators.