(Wired) Scientists are developing the most precise gravity sensors ever made, by wielding the rules of quantum mechanics. Physicist Babak Saif, who works at NASA’s Goddard Space Flight Center, in Maryland, has built an instrument that uses atoms to sense gravity. Since an object’s gravitational attraction is directly related to how massive it is, this device essentially weighs nearby material. The instrument is so sensitive that while they were testing it, it yielded different gravity measurements before and after the scientists broke for lunch, says Saif. “It was detecting the food in our stomachs,” he says.
The quantum sensor, which NASA has developed with Bay Area-based company AOSense, relies on some 100 million cesium atoms. The device launches the atoms inside a cylindrical column and times how quickly they fall. As dictated by quantum mechanics, the atoms behave both like particles and waves. Imagine them sloshing in the column like water waves; as an atom wave ripples up the column and back down, it overlaps with itself to create an interference pattern of crests and troughs.
Researchers want to launch a version of this machine into space to map Earth’s gravitational field, says NASA Goddard geophysicist Scott Luthcke.

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