Vacuum fluctuations produce a force acting on a rigid Casimir cavity in a
weak gravitational field. Such a force is here evaluated and is found to have
opposite direction with respect to the gravitational acceleration; the order of
magnitude for a multi-layer cavity configuration is analyzed and experimental
detection is discussed, bearing in mind the current technological resources.Comment: 7 pages, Latex. Talk given at the Fifth Leipzig Workshop on Quantum
Field Theory under the Influence of External Conditions, September 200
