Hongyu Li

One night, a star at the edge of the sky suddenly flickered and brightened for a few days. It wasn't a supernova, and no cloud passed by — an invisible planet drifted between the star and Earth. Its gravity bent the light of the distant star like a pair of glasses focusing a sunbeam.

In a room with a dead corner, sound doesn’t travel. On the wall there’s a smart mirror: it catches the sound and re-reflects it, making the hidden audible. That’s how a reflective surface works in wireless communication. But if the source is right in front of you, the mirror only creates an echo.

Radio waves from a smartphone, traveling at the speed of light, easily reflect off walls and corners, losing strength. Smart surfaces are programmable mirrors: they catch the scattered signal and redirect it precisely to its target, like a deft magician making a beam bypass obstacles.