How to see quantum gravity in Big Bang traces
Gravitons could be detectable in the cosmic microwave background.
Can a quantum of gravity ever be detected? Two physicists suggest that it can — using the entire Universe as a detector.
Researchers think that the gravitational force is transmitted by an elementary particle called the graviton, just as the electromagnetic force is carried by photons. But most of them despair about ever recording individual gravitons. That is because gravity is so weak that any interactions between gravitons and matter are thought to be beyond human ability to detect in the foreseeable future.
Some physicists, including Freeman Dyson at the Institute for Advanced Study in Princeton, New Jersey, have gone further and claimed that building a graviton detector may actually be physically impossible. Several kinds of detectors have been proposed, but they would fail owing to a combination of instrumental and quantum noise, Dyson said at a conference in Singapore last month in honour of his 90th birthday.