We see you. Wi-Fi signals are everywhere. They’re in our homes, outside, and they pass through most solid materials. Now researchers think they can use Wi-Fi ubiquity for things like detecting the number of people in a room – through a wall. If it sounds like this is a surveillance scheme, it partly is, but researchers think it could also be used for managing office heating, cooling, and lighting systems. Why run the stuff when no one is there? For now, it’s little more than a science experiment, so don’t start freaking out about how your Wi-Fi signal is being used…yet.