Researchers in London have devised a system that gives off no radio waves so it can’t be detected. By sniffing Wi-Fi signals, it can pinpoint a person’s movement inside a building. The UK Military of Defense is exploring whether it might be used in ‘urban warfare,’ for scanning buildings. Technology that starts off for military or law enforcement use often bleeds out and onto the public for covert surveillance. As we move forward and more covert surveillance tech that was previously science fiction becomes real-life technology, it will continue to clash with civil liberties.”]