WiFi is everywhere and still growing in 2018. This video from 2013 seems to support the odd claim that WiFi could potentially be used as part of a monitoring technology to map the layout of your house, your location inside it and even your movements, including hand gestures.
An article May 5, 2017 in Physics is titled, “The Wi-Fi signals that provide internet access can also produce images of the transmitter’s 3D surroundings, even through walls.”
Two researchers in Germany borrowed techniques from the field of holography to demonstrate Wi-Fi imaging. They found that the technique could potentially allow users to peer through walls and could provide images 10 times per second.
A post by Ryan F. Mandelbaum on Gizmodo explains:
Your WiFi router is probably sitting passively in some corner of your room, beaming out invisible light (and the internet). But it’s also sending information on all the stuff the light passes through and around. It’s essentially carrying a holographic image of the room with it.
Researchers have tried using WiFi signals to make images before, but not with an out-of-the-box commercial router, according to a release in the American Physical Society’s Physics. That’s exactly what a team of researchers at the Technical University of Munich has now done, imaging a cross in a room using an unmodified commercial Wi-Fi router.
The method has some drawbacks—it’s slow, and there’s only a set cone of light from the router inside of which accurate images can be produced, outside of which things are blurry. And the whole thing takes a long time, electronic engineer Karl Woodbridge of University College London told Physics. That issue could be fixed with more antennae. Such a system could be used for various indoor imaging purposes; Woodbridge even recommended a set of antennae attached to a “drone or truck” as a promising imaging system.
But the researchers imply that the study should elicit a sense of worry in the reader. “Even encrypted communication transmits a three-dimensional picture of its surrounding to the outer world,” they write.
At this point, we’ve pretty much entered a reality where simply having WiFi in your house can reveal sensitive information.
It is increasingly difficult to avoid WiFi signals, especially in cities, but some choose to turn WiFi routers and other wireless transmitters within their control off at night. This includes cell phones, computers, tablets, laptops and, where possible, smart appliances.