In the last few years it’s become generally accepted knowledge that our universe is full of mysterious dark matter which has mass but is not obviously visible to us. A fringe of physicists have even made controversial claims that they have observed this dark matter in experiments, but now a new experiment makes this claim seem more unlikely.

Dark matter is a type of subatomic particle which is theorized to exist to explain the mass of galaxies, which calculations have shown to be heavier than we would expect. The theorized dark matter must exist in order to explain the way that matter clumps together as well as the movements of stars within galaxies. Although the mathematical evidence of the existence of dark matter is strong, no one has yet been able to identify a dark matter particle despite many attempts. Two primary types of experiment have been used to search for dark matter so far: direct detection experiments, which attempt to record particles of dark matter directly when they pass through the Earth, or indirect detection experiments, which search for the subatomic particles which are created by the decay of dark matter.

Earlier this year, an experiment in Italy called DAMA/LIBRA claimed to have detected dark matter in the galactic halo using social iodide crystal detectors. The crystals of sodium iodide should produce a tiny spark of light when a dark matter particle collides with them, which is what DAMA/LIBRA observed. However, the latest experiment on the topic from South Korea has failed to detect the signal that DAMA/LIBRA found.

The South Korean experiment is called COSINE-100 and used the same type of detector as DAMA/LIBRA, and is the latest in a series of experiments which have failed to replicate the DAMA/LIBRA observations. There is a possibility that the difference in results between the two labs is due to yearly variations in the rate of collisions, with them occurring more at some times of the year than others. But most physicists are skeptical of the DAMA/LIBRA data: “I think this is one more nail in the coffin,” astrophysicist Dan Hooper of Fermilab told Science News.

The latest findings from the COSINE-100 experiment are published in Nature.

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