Dark matter, the invisible substance thought to make up around 85 percent of all mass in the universe, forms an essential part of the standard cosmological model, providing the gravitational glue that holds together entire galaxies. What it actually is, though — and even if it truly exists — remains one of the great mysteries of science.Now, a bizarre event that occurred nearly a mile underground at the world’s largest dark matter detector in South Dakota, the LZ detector, could be the first direct evidence of the substance. Or it could be something else entirely. Either way, it has scientists mystified and excited.In a new paper published Tuesday and has been submitted to the journal Physical Review Letters, physicists running the LZ Dark Matter Experiment say that their detector recorded a stunning subatomic interaction that doesn’t fit anything else ever documented in physics.Again, it’s not necessarily a dark matter discovery — but it’s so unusual that it warranted sharing.“How do you even make sense of one event?” Tom Shutt, a particle astrophysicist at SLAC National Accelerator Laboratory and cofounder of the LZ project, told Science magazine. “We just decided we should publish and think really, really, really hard about what that event could be.”Dark matter is a sort of ghost haunting the cosmos. We can’t see it because it doesn’t emit, absorb, or reflect light, or otherwise interact with any ordinary matter — except through gravity. We see the fingerprints of its gravitational pull all around the universe, in fact. Galaxies aren’t massive enough to hold themselves together with their own gravity, so without the invisible presence of something with incredible mass, the very realms that define the universe, and which we call home, would fly apart.There are countless candidates for what dark matter is, but the prevailing theory is that it’s made up of weakly interacting massive particles, or WIMPs. As their feeble acronym suggests, WIMPs are thought to be a hundred times as massive as a proton, but have such a weak nuclear force that they don’t interact with ordinary particles. Because of their mass, they move much slower than ordinary particles, too, allowing them to clump together and form giant “halos” that provide the gravitational pull for galaxies to form in. There is no single agreed-upon definition of a WIMP, though, and it’s possible that WIMPs could be a whole family of particles, rather than just one.If these theories are correct, then every once in a while, errant WIMPs can bump into the nucleus of an unsuspecting atom and create a trace amount of energy.This is what the LZ detector is built to find. It’s essentially a tank filled with seven tons of liquid xenon, placed 1,480 meters underground in a former gold mine. At such a depth, the preponderance of xenon is shielded from the space radiation that our planet is routinely bombarded with (though there is a still a background level of other interactions that scientists can’t control, but can account for.) Anything that causes a a big enough stir in this controlled, quiet environment would be significant.After spending years poring over the data the detector has collected so far, the physicists found a striking interaction that took place in 2023. Something, we don’t know what, smashed into a xenon particle, and produced a flash of light. If it was dark matter, it produced more energy than traditional WIMP models predict.The scientists say that the detection has about a one in 400 chance of being a fluke. Scientific discoveries, though, need to meet at least a five sigma threshold, meaning that there should be only as roughly one in 3.5 million that it’s a fluke.Still, physicists are absolutely thrilled. Even if this event isn’t a smoking gun by itself, there are other, larger dark matter detectors coming online, such as China’s PandaX experiment and Italy’s XENONnT, that should be able to hunt for the same high energy type of event.“We can perform this study independently with a blind analysis to validate or invalidate LZ’s claim,” Elena Aprile, a physicist at Columbia University and spokesperson for the XENON experiment, told Science.More on dark matter: Physicist Proposes Dark Matter Is Made of Black Holes That Survived Dead UniversesThe post Something Strange Just Happened With the World’s Largest Dark Matter Detector appeared first on Futurism.