The graviton – a hypothetical particle that carries the force of gravity – has eluded detection for over a century. But now physicists have designed an experimental setup that could in theory detect these tiny quantum objects.
In the same way individual particles called photons are force carriers for the electromagnetic field, gravitational fields could theoretically have its own force-carrying particles called gravitons.
The problem is, they interact so weakly that they've never been detected, and some physicists believe they never will.
But a new study, led by Stockholm University, is more optimistic. The team has described an experiment that could measure what they call the "gravito-phononic effect" and capture individual gravitons for the first time.
The experiment would involve cooling a massive, 1,800 kilogram (nearly 4,000 pound) bar of aluminum to a hair above absolute zero, hooking it up to continuous quantum sensors, and waiting patiently for gravitational waves to wash over it. When one does, the instrument would vibrate at very tiny scales, which the sensors could see as a series of discrete steps between energy levels.
Each of those steps (or quantum jumps) would mark the detection of a single graviton.
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