Gravity slows time: clocks on the ground floor tick slower than those on the roof. A new quantum experiment with entangled photons turns this tiny difference into a noticeable signal, amplifying it many times over. Soon, we might witness "altitude-dependent time" right in the lab.
🎯 Over a year, the clock-time difference between a basement and an attic is less than a billionth of a second—the new method makes it noticeable in just a couple of seconds.
🎬 In the movie "Interstellar," time slows dramatically near a black hole; here, it's a modest but real laboratory echo.