Dark matter research is unsettling. Scientists were unnerved when they first noticed that galaxies don’t rotate by the same physics as a spinning plate. The stars at a galaxy’s edge rotate faster than expected. And their motion can only be explained by a lot of invisible matter that we can’t see.
That was exciting more than unsettling when the field was new and ideas were plentiful and had yet to be proven wrong. Researchers consolidated the possibilities into two main camps, complete with clever acronyms: MACHOs (Massive Compact Halo Objects) and WIMPs (Weakly Interacting Massive Particles).
MACHOs are the less exotic possibility. You and I don’t glow or reflect light terribly well, so it’s perfectly reasonable to suggest that space and galaxies contain lots of stuff — planets, stars not quite big enough to turn on and light up, world-gobbling space worms — that we simply can’t see because they are literally dark and we don’t have a big enough flashlight.