A suspicious signal in a dark-matter detector has physicists excited

On June 16th 2023 a strange blip showed up in the detectors of the LUX-ZEPLIN (LZ) experiment, an underground dark-matter detector in South Dakota. That should raise eyebrows. Physicists have been trying and failing to detect dark matter for almost a century. Speaking on the experiment's behalf at the TeV Particle Astrophysics conference on September 1st, Sam Eriksen of the University of Bristol announced that the team has reason to believe the blip could be a "weakly interacting massive particle" (WIMP), a long-suspected candidate for the universe's elusive dark matter.

Physicists are pretty sure dark matter exists. Their best measurements suggest it makes up around 85% of the universe's total mass and is responsible for a number of important jobs, such as making sure galaxies do not break apart. But nothing is known of what the stuff is actually made from. It does not emit, absorb or reflect light or other electromagnetic radiation, and is "seen" only by its gravitational pull.

Over the years, physicists have come up with a motley crew of suspects that could be behind the phenomena. WIMPs are one of the most promising. These hypothetical heavy, sluggish particles interact with other matter only through gravity and an esoteric phenomenon called the weak nuclear force.