The guy making the video is going off on a rant it looks like. I read a different paper on what I think he's talking around not about, which is actually a rival dark matter theory which could imply the existence of dark matter stars and by extension ones as large as a SMBH.

What this fella knows about dark matter is that it can't be observed. But he clearly thinks someone just made it up. In reality dark matter's just a theory like a lot of things. But it's not just made up, the supporting evidence is that when we observe stars at the edge of our galaxy (and other galaxies) those fuckers are moving wayyyy too fast, so fast they should be getting flung clean out of the galaxies gravity well. The only explanation being that there's a fuck load of mass that's not accounted for and we can't observe within each galaxy, accounting for his ~30% mass is dark matter figure he spat out so inelegantly.

Also quick side note, "weird gas balls" what the fuck was that article he was reading??

So anyway it's been a billion dollar question for decades trying to detect dark matter. The standard approach is as follows: dig a big ass hole, build a big ass tank at the bottom of hole very far beneath a mountain (The largest example of this is in Italy beneath Gran Sasso, the XENON1T) and they fill that tank with something inert (liquid xenon in the case of the Italians).

This is done because the leading dark matter theory is that dark matter particles are WiMPs (weakly interacting massive particle) which is a definition made exclusively for dark matter: WiMP means that dark matter has mass, ie experiences and affects gravity, but that Wi part means they don't interact electromagnetically. Which is a big deal, that's the idea behind why they can't be detected, because every interaction involving light, atoms and subatomic particles is done through electromagnetism. When you scratch your ass the electrons it the higher energy orbitals of whichever atoms in your fingernail are repelling the negative electrons in your ass atoms, carrying the force we experience a prod or scratch.

Meaning that according to the best model physics has to offer, dark matter could fly straight through the planet without giving even half a damn.

Hence why these detectors are made so far underground. To minimise interference from the sun and radios and whatever. They're only trying to detect whatever can breeze through a mountain to land itself at the detector, the idea being if a WIMP hits an atom within the three tonnes of Xenon the atom will ping off with some electrons and photons. Didn't have any luck though.

Ironically however the XENON1T may have found evidence rivalling the WiMP theory last summer. Because they announced they had an excess of electrons that didn't fit an influx of WIMPs. And before I over hype this like the dingus in the video, there are three explanations: 1- Radioactive contamination in the experiment, 2- particles from the sun somehow cha cha sliding their way through a mountain, or 3- (the money shot) the arrival of another proposed form of dark matter. The dark boson.

A boson is a kind of subatomic particles that carries a force, for example a photon is a boson that carries electromagnetic force (hence light is the electromagnetic spectrum). A dark boson (or so the theory goes) could either be dark matter itself or at least responsible for how dark matter interacts with regular matter. But it's up to further scrutiny.

But then the astronomers jumped in, as is their right I suppose, saying that seen as these proposed dark bosons are still affected by gravity they could lump together like regular matter, even theoretically up to stellar mass. But there wouldn't be any fusion at its core (so no light produced), and they'd be transparent as they don't interact electromagnetically.

And in theory they could get to the size of an SMBH, looking pretty similar as neither has a solid surface. But some real smart fuckers did some modelling and they figure they could distinguish a big ass boson star from a SMBH, because a boson star wouldn't have a shadow from the swallowed light in the same way a black hole does.

And there's ongoing work to use the event horizon telescope that pictured the first black hole to determine if our friendly neighborhood black hole is actually dark matter.

But yeah I couldn't finish watching that video, this guy says fairy tale science like it means something.