At the end of the 19th century, the ghosthunt became a matter of technology. The observations became more accurate and the evidence more visible. The most important invastigation methods are nocturnal wakes and tracing technology. The equipment exist out of a tape-recorder, a camcorder, a camera, EMF-sensors, infrared equipment, a thermometer, a laptop computer, ... According to Robin Laurence, leader of one of UK's most active ghostunits, ghost do exist for a long time. He doesn't know the exact meaning of ghosts. His favorite explanation is the 'stone-tape'-theory. This theory says that a picture can be taped in the structure of a building, something like a videotape. Thus, under the right conditions, an event which happened 200 years ago, can be 'rewinded'.