Two Kinds of Matter
The first kind is the one we’re familiar with, the matter that we can touch and feel. We’ve been studying that matter as long as we’ve existed. Whether it’s Plato’s forms, or Einstein’s space-time continuum, or Heisenberg’s Uncertainty Principle, we’ve been studying it and measuring it forever. Physicists have developed a detailed model, the Standard Model, that describes this kind of matter with enormous accuracy, down to hundreds of decimal places. It’s the most-tested and most accurate model ever created by science. Well, that and General Relativity, which we’ll get to later.
Anyway, that’s one kind of matter, a kind we understand in detail.
What’s the evidence for two kinds of matter?
Back in 1933, Fritz Zwicky started to observe something unusual about the rotation of galaxies. He could measure the speed of galactic rotation and roughly calculate the mass of the galaxies. His calculations showed that the rotation was so fast that the galaxies should fly apart, that there wasn’t enough mass to hold them together.
Zwicky was a meticulous scientist, so no one argued with his measurements. However, he was also a snarky kind of guy, and no one liked talking to him. The easiest thing to do was to just ignore him, his snark, and his puzzling observations, which is what happened for the next forty years or so.
Eventually, however, it became obvious he was onto something, especially thanks to Vera Rubin’s work in the 1970s. It eventually became clear that a halo of invisible matter surrounded almost all galaxies, and this invisible matter was the extra mass needed to hold them together. We know this matter exists because we can observe its gravitational effects. It’s what’s holding galaxies together despite their rapid spin. Detailed measurements of the cosmic background radiation provided even more, if indirect, confirmation of this invisible halo.
We call this invisible matter “dark” because we can’t see it directly. In particular, it doesn’t interact with photons.
Whatever it is, we know from its gravitational effects how much of it there must be. The answer is a lot. There’s about six times as much dark matter as regular matter in the Universe.
Dark Matter
Getting back to regular matter and the Standard Model, it’s natural to think there must be an unknown component of that model, a particle or maybe a field, that accounts for dark matter. Perhaps dark matter arises from something similar to, say, the Higgs Boson which accounts for the mass of ordinary matter.
There’s something called “supersymmetry” which gives candidates, WIMPS and Axions for example, for such a particle or field. Physicists have been looking at candidates for a couple of decades with increasingly sensitive experiments. They have found exactly nothing. Well, not quite nothing. They’ve managed to restrict range of possible places to look. It’s pretty narrow at this point. It’s bad enough that some physicists are starting to think this is a dead end.
There’s an emerging theory that supposes an entire “dark universe” that coexists with the one of our senses, the one of the Standard Model. This theory hypothesizes that this “dark universe” has its own version of a “Standard Model.” The dark universe and our universe interact primarily, or maybe only, through gravity.
Einstein teaches us that gravity involves the shape of space-time, so the dark universe would share the same space-time continuum as us. But, if this new idea is right, the dark universe might have different laws of physics. Different laws of physics mean that anything is possible in this universe, a universe that’s right here, occupying the same space-time that we occupy. It might even have had its own equivalent of the Big Bang, but not contemporaneous with ours, whatever “contemporaneous” might mean in this context.
This idea is brand new, having only been proposed in the last year or so. It’s intriguing, especially in light of the failure to find evidence consistent with the Standard Model for dark matter. In fact, the primary evidence for the theory is the failure of these experiments. Not the only evidence, though. It might also explain some problems related to the earliest nanoseconds of our universe. The jury’s out on that, and it’s right to be skeptical about a radical new theory like this one.
In any case, finding out the nature of dark matter is a Big Open Problem in physics.
I’ll relate this back to fantasy worlds and the idea of a “wheft” later, but next I want to mention the Big Bang and dark energy.
Two Kinds of Matter
The first kind is the one we’re familiar with, the matter that we can touch and feel. We’ve been studying that matter as long as we’ve existed. Whether it’s Plato’s forms, or Einstein’s space-time continuum, or Heisenberg’s Uncertainty Principle, we’ve been studying it and measuring it forever. Physicists have developed a detailed model, the Standard Model, that describes this kind of matter with enormous accuracy, down to hundreds of decimal places. It’s the most-tested and most accurate model ever created by science. Well, that and General Relativity, which we’ll get to later.
Anyway, that’s one kind of matter, a kind we understand in detail.
What’s the evidence for two kinds of matter?
Back in 1933, Fritz Zwicky started to observe something unusual about the rotation of galaxies. He could measure the speed of galactic rotation and roughly calculate the mass of the galaxies. His calculations showed that the rotation was so fast that the galaxies should fly apart, that there wasn’t enough mass to hold them together.
Zwicky was a meticulous scientist, so no one argued with his measurements. However, he was also a snarky kind of guy, and no one liked talking to him. The easiest thing to do was to just ignore him, his snark, and his puzzling observations, which is what happened for the next forty years or so.
Eventually, however, it became obvious he was onto something, especially thanks to Vera Rubin’s work in the 1970s. It eventually became clear that a halo of invisible matter surrounded almost all galaxies, and this invisible matter was the extra mass needed to hold them together. We know this matter exists because we can observe its gravitational effects. It’s what’s holding galaxies together despite their rapid spin. Detailed measurements of the cosmic background radiation provided even more, if indirect, confirmation of this invisible halo.
We call this invisible matter “dark” because we can’t see it directly. In particular, it doesn’t interact with photons.
Whatever it is, we know from its gravitational effects how much of it there must be. The answer is a lot. There’s about six times as much dark matter as regular matter in the Universe.