Gravitational-Wave Research Seminar
Quantum electrodynamics predicts that light slows down in the presence of external magnetic or electric fields. Since this slow-down depends on the orientation of the external fields with respect to the polarization of the light, a birefringence of the vacuum results. Vacuum birefringence is very weak, and has not yet been observed, even though a number of experiments world-wide has tried and continues to do so. I will report on these attempts to detect birefringence of the vacuum, highlighting recent progress of the PVLAS experiment located in Italy. All of these experiments measure the polarization of the light, but a different approach to this problem may be to use ultra-sensitive length measurement devices, as has been proposed by different researchers in the past. Gravitational wave detectors are among the most sensitive of such devices, and I will try to shed some light on the possibility of using gravitational wave detectors for this purpose.