This thesis consists of two subjects, that are both a consequence of radiation pressure. In optomechanics, light is used to influence the motion of a trampoline resonator. It is possible to slow... Show moreThis thesis consists of two subjects, that are both a consequence of radiation pressure. In optomechanics, light is used to influence the motion of a trampoline resonator. It is possible to slow down this motion, cooling it from room temperature to an effective temperature of several milllikelvins, The other subject is how superconductivity influences the Casimir force between a niobium-titanium-nitride plate and a gold microsphere. This has been investigated both theoretically and experimentally. Show less