Introduction to general relativity in a setting with comparatively strong gravitational fields. This has become possible thanks to precision observations of binary pulsars. In such a star system, two highly compact neutron stars orbit each other. At least one of them is a pulsar – an astronomical object that emits a tight beam of radiowaves. These beams strike the Earth at very regular intervals, similarly to the way that the rotating beam of a lighthouse means that an observer sees the lighthouse blink, and can be observed as a highly regular series of pulses. General relativity predicts specific deviations from the regularity of these
Optical beam-induced current Optical beam-induced current Optical beam induced current (OBIC) is a semiconductor analysis technique performed using laser signal injection. The technique uses a scanning laser beam to create electron–hole pairs in a semiconductor sample. This induces a current which may be analyzed to determine the sample's properties, especially defects or anomalies. Conventional OBIC scans an ultrafast laser beam over the surface of the sample, exciting some electrons into the conduction band through what is known as 'single-photon absorption'. As its name implies, single-photon absorption involves just a single photon to excite the electron into conduction. This can only occur if that