U.S. Navy researchers stumbled upon the concept of radar when they noticed that a plane flying past a radio tower reflected radio waves.
Scientists have now applied that same principle to make the first device that tracks existing Wi-Fi signals to spy on people through walls.
When a radio wave reflects off a moving object, its frequency changes—a phenomenon called the Doppler effect. Their radar prototype identifies frequency changes to detect moving objects. It’s about the size of a suitcase and contains a radio receiver composed of two antennas and a signal-processing unit.
In tests, they have used it to determine a person’s location, speed and direction—even through a one-foot-thick brick wall. Because the device itself doesn’t emit any radio waves, it can’t be detected.
A group of more than 85 scientists have issued a joint rebuttal to a recent U.S....
Kate Adamala had been working on something dangerous.
At her synthetic biology lab, Adamala had been taking...
An ancient and “nearly naked” black hole that astronomers believe may have been created in the.../https://tf-cmsv2-smithsonianmag-media.s3.amazonaws.com/filer_public/28/42/284283dd-663b-4e1a-a610-c2b440c84f65/ezgif-34f9a279a9f974.jpg)
Early humans who made some of the oldest known stone tools might have traveled miles to...
