Dear students, dear colleagues Please join us for today's colloquium by Oskar Painter California Institute of Technology, Pasadena, USA who will talk about Quantum Back-Action in Recent Cavity-Optomechanics Experiments Please visit our web page http://www.colloquium.phys.ethz.ch for details. Best regards Thomas Gehrmann Michael M. Meyer Juerg Osterwalder Renato Renner