hypnosec writes: Researchers at University college of London have applied principles of radar used in defense and designed a detector using home based Wi-Fi router to spy on people across walls. Using the principles behind the Doppler effect, wherein radio wave reflects off a moving object, Karl Woodbridge and Kevin Chetty, at University College London, have built a prototype unit that uses Wi-Fi signals and recognizes frequency changes to detect moving objects. The size of the prototype unit is more or less the size of a suitcase. The unit contains a radio receiver comprising of two antennas and a signal-processing unit. The duo carried out test runs and the results were interesting. They managed to determine a person’s location, speed and direction and that too even through a one-foot-thick brick wall. The device can be used to spot intruders, monitor children or the elderly, and can even be used in military. Link to Original Source
"The urge to destroy is also a creative urge."
[ed. note - I would say: The urge to destroy may sometimes be a creative urge.]