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 concluded that this was due 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 almost every galaxy, 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 stars in galaxies together more tightly than their gravity allows, so they 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.
However, the standard model needed a particle to cause dark matter, so it suggested WIMPs (weakly interacting massive particles), 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, the standard model doesn’t explain 85% of the matter in our universe.
What then does a processing model suggest? If mass arises when net processing repeats at a point, what halo could do that? We expect the black hole at the galaxy center to trap light in a circle around it. Light close to the black hole is pulled in, and light far away escapes, but at some radius, it will constantly circle in a loop (Figure 4.27).
This halo of light will build-up over time, as more photons join, until it is a dense flow of only wave-fronts, with no tails to cancel them. Light circling the opposite way would be the same, as in our matter world all light vibrates first up and then down. No particles are created, because normal light doesn’t collide, but the result is a constant net processing excess at every point, which in this model represents mass. A dense halo of light around a black hole would then create mass as usual, but without particles that could be seen.
Recall that by the pass-it-on protocol (2.4.4), points of space are interrupt driven so each cycle, a halo point would first pass on the current photon, then process the next photon received. Hence a halo of dense light, where photons arrive every cycle, will only process photon heads not tails. This interrupt loop is stopped by expanding space, but it may not be sufficient in this case. If so, the result is a permanent net processing excess throughout the halo, which in this model causes mass.
It follows that the halo of light circling a black hole will generate mass. This mass, like that of ordinary matter, comes from light 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, it is no surprise that 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. It also lets small galaxies 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, a dark matter halo can’t, because photons either pass through it 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, and if most matter is dark, a model based on particles has no future.