Inside a cylinder mounted on a rotating table top, Amherst College physicists are trying to detect tiny perturbations within mercury atoms, caused by long-range interactions with particles in the Earth’s interior.
Although it’s something of a scientific longshot, if the experiment detects anything, it could reveal new physics — exotic particles and a force of nature never before seen — that would shake up the physics world.
In a study published Thursday in the journal Science, the Amherst team and a collaborator at the University of Texas at Austin reported that they had not discovered new physics yet, but had put limits on the energy associated with the force that would be carried by hypothetical particles — which include the existentially evocative “unparticle.” The team is homing in on the sensitive measurements it might need to detect new physics; the new results demonstrate that the theoretical force, if it exists, is extraordinarily weak.
“We are all doing what physicists do, which is we’re trying to check around the edges and see if things hang together. Theorists have proposed these particles, as possible things that we don’t have any reason to believe they don’t exist,” said Larry Hunter, a physics professor at Amherst. (In full disclosure, Hunter was one of my professors.)
“The probability of finding something has got to be regarded as not high, but the payoff is tremendous if you turn up a signal,” he said.
The modest-size experiment fits easily in a room, and is an attempt to verify or rule out physics that lie beyond the widely accepted understanding of the fundamental building blocks of the universe, called the Standard Model. It’s an opposite tack from the one taken by the best-known physics experiments, such as the Large Hadron Collider, which require multinational teams of thousands of scientists and billions of dollars. The Amherst experiment uses precision measurements of a relatively small-scale setup, and drew on the efforts of a small team of five scientists.