"Invisible forces that explain events, in mysterious ways" The cold dark matter component of the standard cosmology is not the first time anomalous momentum wa

"Invisible forces that explain events, in mysterious ways" The cold dark matter component of the standard cosmology is not the first time anomalous momentum was attributed to invisible (as in, does not experience electromagnetism) matter. Twenty-six or so years from proposal (which incidentally was about two years before the discovery of the neutron) to direct detection: https://www.wikiwand.com/en/Neutrino#/History https://www.wikiwand.com/en/Neutrino#/History Note that neutrinos are hot dark matter; hot because they move quickly compared to the speed of light. While neutrinos are definitely part of the dark matter sector, they cannot be the sole component because their hotness would smear out galaxies. A colder neutrino would work very well to match all the observations associated with observed anomalous momentum that strongly suggests dark matter, and hunts are on for direct detections of a cold (implying high rest-mass) neutrino-like particle. There are other options, of course, but the four key things are: there is non-ignorable anomalous momentum; matter generates momentum (in this case, through gravitation); there is no visible matter associated with the momentum in question (that's why it's anomalous); and we have discovered non-visible matter in the past while trying to explain other cases of anomalous momentum.