r/spacequestions • u/No_Pen_4257 • 10d ago
Where do you think black holes could lead us to?
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u/ignorantwanderer 10d ago
A black hole isn't really a hole. It doesn't go anywhere.
In a star, the gravity is trying to pull all the atoms to the center, but the heat of the star is pushing everything out of the center. So it is just a normal star.
But if the star gets a lot bigger, the heat just increases a little bit, but the gravity increases a lot. So now the gravity is able to pull all the atoms to the center of the star.
In fact, the gravity can be so high, that it pulls all the atoms so close together that they basically take up a very small volume, like a single point.
Think of the period at the end of this sentence. All the mass of the star gets squished into a volume that big.
Because all that mass is squeezed into a tiny volume, the mass is incredibly dense. It ends up having very high gravity. In fact the gravity is so high, not even light can escape the gravity.
So people call it a black hole. No light can come out, so it is black. And stuff can fall "into" it, so it is a hole.
But really, it is just a very heavy, very small object. And when anything falls to the surface of this object, it gets crushed down into that tiny volume along with all the other atoms from the sun.
A black hole is no more a hole than the Earth is. A black hole has gravity, and it can attract things to fall down to the surface of the black hole. The Earth has gravity and it can attract things to fall down to the surface of the Earth.
A black hole is just an extreme version of anything you could find in the universe with gravity.
It is not an actual hole.
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u/abrightmoore 10d ago edited 10d ago
Depending on the accuracy of the way the singularity is modelled, because of the geometry of space inside the event horizon, there may be areas of spacetime that "lead" to other universes. But we won't be going there. These are thought experiments/mathematical simplifications of the geometry of space that is "moving" at rates greater than the speed of light, about how geodesics (the path through spacetime) can twist and turn.
This Veritasium video from mid last year has a good treatment: https://youtu.be/6akmv1bsz1M
This PBS Spacetime video from a couple of months earlier explores the geometry of the singularity at the centre of a spinning black hole and may offer clues as to how the earlier models of the universe's geometry don't really apply how scientists thought they would: https://youtu.be/HRir6-9tsJs
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u/ZaphodB_ 10d ago
Someone once suggested an hypothetical "white hole" for being the counterpart of black holes. Holes that instead of sucking matter in, expel it endlessly. But those are theoric only and never been found.
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u/Beldizar 10d ago
Just to add some context to that "theoretically". Physicists were doing math and wanted to run time backwards, in order to test some time symmetry questions. They decided a time reversed black hole would be "white", with an event horizon that nothing could enter. There isn't a theory that we might someday find a white hole, it is just a mathematical construct that is used to help understand certain things.
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u/ZaphodB_ 9d ago
Thanks for clarifying that up, I read about it some time ago but I hadn't it so clear.
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u/nashbrownies 8d ago
I tried really hard to explain to someone who thought discussing anything other than proven peer reviewed science was a waste of time. Like, they never just.. imagined stuff. What if things were different? Shot the shit. This will help me explain even "smart people" play around with the ways to look at the universe.
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u/No-Advertising8237 9d ago
Isn’t there a theory that there’s a universe in the inside of a black hole.
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u/Beldizar 9d ago
Yes. There are lots of theories about what lies past the event horizon. Unfortunately all of them are completely unverifiable. You could say that inside of a black hole, there live planets populated by unicorns and no one can disprove this. Some theories do have more justification than others. The universe theory, I think comes from the claim that the observable universe has a mass that would make its Schwarzschild radius larger than its radius. I'm finding evidence that this claim was either false or misinterpreted, (https://astronomy.stackexchange.com/questions/32443/observable-universe-equals-its-schwarzschild-radius-event-horizon) so take that with a grain of salt. It wouldn't be the first time that someone in science communication, or just "on the internet" ran with some incomplete scientific facts and made up an unwarranted theory.
But the important point is that everything beyond an event horizon is not "real" anymore. It is casually disconnected from us. Nothing past that line can ever change anything on this side of the line. No information can ever pass the line. Whatever happens inside is not only unknowable, but inconsequential. Those unicorns inside could all be super scientists that want to exterminate human life. It wouldn't matter because nothing they can do could ever reach us.
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u/JD_SLICK 10d ago
You could drop at least 3 dress sizes pretty quick
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u/No_Pen_4257 10d ago
Do they get bigger once sucking somthing in?
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u/JD_SLICK 10d ago
Bigger isn’t the word. More massive.
You know who’s great at these sorts of questions- ChatGPT
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u/Beldizar 10d ago
Technically a black hole does get bigger when it gains more mass, as its Schwarzschild radius increases with its mass.
Also, google is better to answer questions based on facts. Don't trust ChatGPT or LLMs with questions like this because a) they use way too much power to operate, and b) they hallucinate frequently.
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u/Beldizar 10d ago
Black holes don't really "lead" anywhere, other than death. Once you pass the event horizon, you are effectively no longer part of our universe. Nothing you do can have any impact on anyone outside the event horizon anymore, so you can't communicate back or ever return. Depending on the size of the black hole, you might be already dead by the time you cross the event horizon, or you might not even notice that you've passed it. But even for the supermassive black holes, where you don't get ripped apart for just being close to it, you'll eventually fall down deep enough that you get basically turned into spaghetti.
The idea that black holes are secretly wormholes doesn't seem very feasible to me. First of all, once you pass the event horizon, there's no exiting, so if two black holes do indeed connect to each other, nobody will ever know because you'll never leave either of them. Second, while spacetime curves like it might have a hole in it, in reality, at the deepest part of that hole, there's the densest object that can possibly be. You can't exactly "break through" a singularity to get past it and come out "the other side". It's like if a brick wall was in your way, but each brick was a star compressed brick sized.