We have no idea what dark matter is. We know a lot about dark matter and how it acts, so we know what physical properties it must have. However, no known substance has all of the requisite dark matter qualities. So we’re at a loss.

Neutrinos are the closest thing we have. They only have a weak interaction with other matter and have a weak interaction with light, hence they can be classified as dark matter. The main difficulty is that the three types of neutrinos that have been discovered all have incredibly minuscule masses. As a result, they travel across space at nearly the speed of light. As a result, neutrinos are a type of “hot” dark matter, similar to how a hot gas consists of fast-moving molecules. We know that cosmic dark matter must be predominantly cold based on dark matter measurements such as galaxies clustering. Although neutrinos may make up a small amount of dark matter, the majority must be made up of something else.

However, because neutrinos come so near to fulfilling the characteristics of dark matter, some scientists believe dark matter might be a previously unknown kind known as sterile neutrinos. Neutrinos, like other elementary particles, have a property known as helicity. A neutrino can spin clockwise (left-handed helicity) or counter-clockwise (right-handed helicity) throughout its journey (right-handed). Neutrinos, on the other hand, are unusual in that they can have either form of helicity. Left-handed neutrinos and right-handed anti-neutrinos are the only ones we observe.

The helicity of neutrinos and anti-neutrinos. Credit: Universe Review


This suggests that if right-handed neutrinos exist, they interact solely with gravity and not with normal matter. As a result, they are “sterile.” Sterile neutrinos would be “cold,” and might be the answer to the dark matter problem if they had a considerably bigger mass than ordinary neutrinos. It’s a fantastic notion, but it doesn’t appear to be true, according to a recent research.

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The data for this new study came from Fermilab’s MicroBooNE team. The MicroBooNE detector was bombarded with neutrinos to investigate what kinds of interactions they have with ordinary stuff. Earlier experiments, such as Los Alamos’ Liquid Scintillator Neutrino Detector and Fermilab’s MiniBooNE, have found more events than the conventional model predicted. One theory is that sterile neutrinos interacting with other neutrinos produce an overabundance of electrons in the observed occurrences. Another possibility is that the data was skewed by background radiation. Both of these alternatives are ruled out by the MicroBooNE cooperation, which is precise enough to look at both of them. Background photons are ruled out with 95 percent certainty, while sterile neutrinos are ruled out with 99 percent certainty.

Something strange is going on if the earlier excess found in MiniBooNE is a true consequence (and we have no reason to believe it isn’t). There may still be sterile neutrinos, but their interactions must be more delicate than theories suggest. There might potentially be some intricate interactions between normal neutrinos that the conventional model does not account for. In any case, there’s a lot more to learn, and we’ve just scratched the surface of the problem.

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