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Comment by cogman10 | Hacker News Reader

I'm sure I'm not the only one that's thought of this, but could this be "dark matter"? Is the universe simply filled with these rouge black holes?

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> rouge black holes

They makeup much of the stylish universe in the cosmos ;-)

Just kidding, I know you meant rogue.

I would assume we'd see a lot of more tricks of light bending if they did. Light lensing was used to confirm relativity by looking for multiple super novae signatures from the same event, which passed by large black holes on their way here!

Depends on the size, position, and number of black holes, right? We see lensing currently because of super massive black holes that we know about. But if there's a bunch that are basically as massive as our sun (or less) then we are dealing with event horizons ~3km or less. It'd be pretty hard to spot those as the diffraction would be rounding errors.

But are there enough of them that we're really the rogue matter that is abnormal?

My logical leap is that if blackholes constitute our measure of dark matter (25% of proportion) or dark energy (68% of proportion) that they'd attract each other and glob together. Also true of gravstars.[0]

[0] https://www.youtube.com/watch?v=BmUZ2wp1lM8

These would be 'primordial' black holes: https://en.m.wikipedia.org/wiki/Primordial_black_hole

This would certainly be some of it but the awkward fact is that we've positively identified so very little of the matter that makes the universe the shape that it appears to us to be that we could double the known matter in the universe with black holes and we'd still only be a 10th of the way there.

However if we could eliminate the false signals from invisible (singularity) matter I am hopeful that will give us a clearer idea of whatever the rest is.

I can't remember who I heard talk about this, but scientists have considered this. I think there was a good reason for why it doesn't seem to match observations.

If a significant portion of dark matter was made of these we would see a lot more gravitational lens distorions of distant objectes. There are further hard limits on how much baryonic dark matter there can be from big bang nuceleo synthesis. I think that would also put limits on contributions from lone black hole contribution.

That was my first thought too. A cursory search indicates we would see a lot more gravitational lensing in our observations if that was the case.

Found a couple of videos on it too

https://youtu.be/qy8MdewY_TY

https://youtu.be/d0wV5frSb6s

Probably not the main component of dark matter, but definitely a spooky and fascinating piece of the cosmic jigsaw

There are some theories that primordial black holes could be dark matter. It's not a mainstream view though.

You're not the only one. This is a fairly old idea.

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