Scientists in England can now see through walls ­— kind of. Researchers have created a luggage-sized device that can detect human activity behind a one-foot thick brick wall based on Wi-Fi signal frequencies that ricochet as people move around.

 

According to Popular Science, the "passive radar system" works much the same as regular radar does and is able to accurately detect the speed, location and direction of a person as they move about. However, if you stay still, you'll stay invisible, because the system works by measuring Wi-Fi strength and frequency changes.

 

While the device has the potential for peaceful, civilian applications such as monitoring children or home protection, CNET reports the military has already taken an interest in the technology as a potential tool in urban warfare.