In the 1950s, astronomers discovered that our galaxy rotated as if it had more matter than its stars allowed, five times more in fact. They attributed this to dark matter, dark because it can’t be seen and matter because it caused gravity. The rotation curves of other galaxies suggested they were the same, so astronomers now estimate that about 85% of the matter of the universe is dark. Based on its effects, dark matter seems to exist as a halo around the black hole at the center of most galaxies, including ours.
What then is dark matter? It isn’t the matter we see because light can’t detect it, it isn’t anti-matter because it has no gamma ray signature, and it isn’t a black hole because there is no gravitational lensing, yet it holds galaxies together so their stars don’t fly off. It made our galaxy stable, so the matter-producing factories we call stars had time to make the atoms needed for life and us. Dark matter is the glue that binds galaxies together, but its cause is unknown.
The standard model proposed that WIMPs (weakly interacting massive particles) cause dark matter, but the result was just another wild-goose chase. Despite talk of super-WIMPs (Feng, Rajaraman, & Takayama, 2003), the search for WIMPs, like gravitons, proton decay, and squarks, led nowhere. A particle like that should have been seen by now so currently, physics can’t explain 85% of the matter in our universe.
What then is the processing alternative? If mass is the net processing that repeats at a point, could a halo do that? We expect the black hole at the center of our galaxy to trap light in a halo around it. Light near the black hole is pulled in and light far away escapes but at some radius, it will constantly circle it (Figure 4.27).
This halo of light will build-up over time as more photons join, until it is a dense flow of wave-fronts that move on each cycle. Light circling the opposite way would be the same, as light in our world vibrates first up and then down. No particles are created because this light isn’t colliding, but if the result is a constant net processing excess at every point, that is mass. A dense halo of light around a black hole could then cause mass as usual but without visible particles.
Yet the halo passes on photon tails as well as heads, so wouldn’t the result cancel out? Current research suggests that dark matter has a tiny negative charge, about a millionth of an electron’s charge (ScienceAlert), so it seems that at each halo point, more heads are processed than tails. The effect is very weak, but over a huge halo it adds a lot of mass. If so, a permanent net processing excess throughout the halo will create mass.
The halo of light circling a black hole would then generate mass as particles like electrons do, but instead of being at a point, it is spread through a stream of light. If extreme light trapped at a point causes particle matter, then dense light trapped in orbit around a black hole can do the same. This explains why the halos of galaxies don’t collide when they do, but remain around each galaxy when they separate. Note that small galaxies can exist with no black holes, and galaxies that have lost their stars can consist of 99.9% dark matter.
Ordinary and dark matter then arise in similar ways, but while particles can be seen, dark matter can’t, because photons either pass through the halo at an angle or join the stream. The standard model search for WIMPs was then fruitless because dark matter isn’t based on particles at all.