Searching for dark matter in Minnesota's deepest iron mine.

After a titillating rumor last week seemed to be debunked, it looks as though physicists in Minnesota may have indeed discovered the weakly interacting particles (WIMPs) that constitute dark matter.

Dark matter has been an invisible lurker up until now. But scientists believe that it makes up approximately 25 percent of the universe, based on its gravitational effects on the visible universe. Unrelated dark energy makes up nearly 70 percent of the universe, and the more familiar atomic matter represents just 4 percent.

The mine’s dark matter particles may have revealed themselves as two tiny heat signatures in germanium and silicon that have cooled to a near absolute-zero temperature. Still, scientists caution that there’s a 20 percent chance the heat signatures just represent background radioactivity in the underground cavern.

If confirmed, the find could represent the first evidence of supersymmetry, or the theory that predicts a shadow partner for every known particle.

The international team investigating the Minnesota mine, called the Cryogenic Dark Matter Search, announced the new results during simultaneous talks. They also plan to post their findings online in a paper, and have begun planning to deploy a larger dark matter detector called SuperCDMS.

A physicist told the New York Times that the discovery had triggered “a high level of serious hysteria” among dark matter experts. But true confirmation might not occur until more sensitive dark matter detectors, such as the xenon detector located deep beneath the Italian Alps, weigh in.

[via New York Times]