astronomy

lemming, 4 dni temu w Dark Matter Black Holes Could Fly through the Solar System Once a Decade

I thought these were disproved by lack of gravitational microlensing?

InvertedParallax, 4 dni temu

The main way you’d see that kind of microlensing is if they aggregated.

But given the way gravity works, they should aggregate, otherwise why call them black holes?

Classy, 4 dni temu

If they were relatively evenly distributed would that counteract lensing?

InvertedParallax, 4 dni temu

Yes, it would just be surprising because, gravity should make them not be evenly distributed.

The whole thing with dark matter is that it’s this magic stuff that causes gravity but isn’t affected by it, which… is not how gravity normally works.

Though there is still room for it, we just need a better framework other than “I added 3 and 5 and got 12, so obviously I must mean to add 3 and 5 and 4 too”.

MartianSands, 4 dni temu

You’re mistaken. Dark matter, whatever it is, isn’t affected by anything except gravity. It interacts with gravity just like “normal” matter.

The evidence is also significantly better than you’re describing

InvertedParallax, 4 dni temu

Then it should also coelescce, particularly since it doesn’t have the em force to keep it repelled, the universe should be dominated by massive dark matter black holes.

Yes, there’s math that explains part of the distribution, but also there is 0 force opposing any collapse we’d have a lot more neutron stars and other degenerate matter catalyzed by dark matter.

We have hypotheses like this when our observations don’t make sense and we need to explain them, it’s definitely a possibility but we still have room to understand the large scale physics at play.

MartianSands, 4 dni temu

You don’t need a force to prevent collapse if there’s no drag force to slow things down. It would actually be almost impossible for a cloud of dark matter to collapse since any individual particle has momentum and no way to slow down, so they’ll all be in some sort of mutual orbit

InvertedParallax, 4 dni temu

I’m guessing you’ve seen as many lorentz attractor simulations as I have, what always happens is something like tidal effects or angular momentum means 90% slow down while a few particles get shot out of hell at ludicrous speed.

The effect is similar to drag, and is basically how we get entropy even without em effects.

Gork, 4 dni temu w Dark Matter Black Holes Could Fly through the Solar System Once a Decade

What would happen if one of these tiny black holes hit Earth? The article doesn’t really talk about it.

Donjuanme, 4 dni temu

Absolutely nothing.

Also not sure why they wouldn’t evaporate nearly instantaneously. Sounds to me like more dark matter bunk.

deegeese, 4 dni temu

Passing near the earth, we’d get some strange tides. Passing through the earth, it would eat earth.

Rhaedas, 4 dni temu

Nonsense. The event horizon on such things is incredibly small, as is the mass vs. that of Earth.

deegeese, 4 dni temu

You don’t need the event horizon, you just need local gravity around 1G. For the masses described in the article, that radius is from hundreds of meters to 10s of kilometers.

Rhaedas, 4 dni temu

Which still wouldn't do what you suggest. The mass is the same, so it has the same effect from a distance. Unless by "eat earth" you meant it would take in dirt until it suck to the core, still about the same mass.

Bluetreefrog, 4 dni temu w Dark Matter Black Holes Could Fly through the Solar System Once a Decade

The book, Seven Eves is about one of these hitting the moon.

Davel23, 4 dni temu

The cause of the incident is never specified in the book.

thebardingreen, 4 dni temu

The book Earth by David Brin is about one of these hitting the Earth

Lemming6969, 3 dni temu w Dark Matter Black Holes Could Fly through the Solar System Once a Decade

What if dark matter is some form of black hole or exotic ultra dense material made entirely out of the missing antimatter, which for whatever reason doesn’t otherwise interact with electromagnetism? 2 birds, 1 stone.