These mfers are like glitches in reality. Even trying to wrap my head around wtf they are freaks me out. How the hell can there be a thing in this universe that has infinite density? That doesn't even make sense.
Ugh
Black holes: baby shit, who cares, turning into spaghetti? Sounds delicious.
Going to social function: terrifying, monumental task, what if they are mean to me and make fun of my outfit
Me: everyone will think I'm weird and ugly and pelt me with rocks and half-empty sodas
Also me: makes everyone laugh, gets compliments on my insight and encouragement on all of my efforts, get told to write more by literally everyone who reads a shred of my writing
Me: As expected everyone hates me and is silently willing me to spontaneously combust
Black holes are not infinitely dense because physical infinities do no exist, you are correct that it doesn't make sense and anyone claiming this is wrong.
The foundation of quantum mechanics is that the universe is quantum, which is to say, it is made up of a finite quantity of discrete "bits." An area of one Planck Length by one Planck Length contains one bit of information, either it contains mass or it doesn't. The concept of infinite density violates this by claiming that an infinite amount of information can be stored in an area smaller than that, which contradicts our understanding of quantum mechanics on a very fundamental level. The highest density something can have is to contain one bit of mass in every Planck area.
The reality is that black holes come from stars, with finite mass, and they occur when the force of gravity becomes so great that it overpowers the nuclear forces holding an atom together, causing electrons to collapse into the nucleus, and even for the subatomic particles to break down. However, the mass still occupies a discrete area, incredibly small but not infintismally so.
Now having said that, black holes are currently a controversial and unresolved subject because no consensus has formed around a satisfying resolution to what's called the Black Hole Information Paradox, which pits several fundamental principles against each other.
Information, in the context of physics, cannot be destroyed, because the destruction of information would mean reducing the complexity of the universe, reducing entropy and violating the second law of thermodynamics. What this means is that it's hypothetically possible, given sufficient knowledge of the physical world, to reconstruct everything that has ever happened. Every event that occurs leaves behind evidence, and that evidence can be jumbled up and garbled beyond recognition, but never completely erased from history.
For this to be true in the context of black holes, it is necessary for there to be some method of extracting information from a black hole - but there isn't. Or at least, nobody has been able to explain how that would work. Some have speculated that the information is emitted in Hawking radiation, but this doesn't really make any sense because of what Hawking radiation is. Others have speculated that the information could be stored on the event horizon, but this has been rejected as the event horizon is just a mathematical abstraction (this is sometimes referred to as a question of whether black holes have "hair," with most physicists agreeing that "black holes have no hair"). Various other hypotheses have been proposed over the decades, but all of them seem to contradict some principle that we have very good reasons for believing in, and we can't overturn any of those principles without solid evidence, which we don't have.
To restate the problem: if black holes can consume physical things that have high entropy, and reduce them to a state of low physical complexity, then they are capable of reducing entropy in a closed system, and our understanding thermodynamics is fundamentally wrong. If they are capable of storing that entropy in an infintesmally small area, then our understanding of quantum mechanics is fundamentally wrong. If it's possible to retrieve information from a black hole, then our understanding of relativity is fundamentally wrong. So either some fundamental principle in physics is wrong, or someone will eventually come up with some very clever solution that reconciles these competing principles.
So either some fundamental principle in physics is wrong, or someone will eventually come up with some very clever solution that reconciles these competing principles.
I hope something is wrong, that's more fun.
Since I found someone willing to explain this in the wild, could you say more about Planck units?
If so
Am I understanding the implication correctly that, as far as our ability to measure things is concerned, the universe is organized into something analogous to voxels (in the true sense) and frames? How does movement work, is it just the rate at which quanta blip from one unit of Planck space to the next? If laterally adjacent spaces have the same mass, does that mean if they move laterally at the same speed, at each interval one space remains the same while one loses mass and another gains it? i.e. if you have 01100 and move it one to the right, you have 00110, with the middle one not changing.
It's been years since I studied it so I may need to brush up my knowledge to explain it properly.
One thing to note is that there are different interpretations of QM, so one might agree with the interpretation of flipping bits, while another might argue that the object is moving through infinitely-divisible space, on a smaller scale than it is possible to observe, and the bits are just the limits of what is measurable. For practical purposes, either works and it's more of a philosophical question of whether we can extend scientific principles to things and scales where it's impossible to test or observe.
I definitely recall something about using two-dimensional pixels rather than three-dimensional voxels in this context, even though it seems extremely counter-intuitive. It has something to do with surface areas but I definitely can't explain it on my lunch break lol.
Black holes are not infinitely dense because physical infinities do no exist
counterpoint Elon Musk is infinitely dense
i gotta get a degree or something cuz this shit still makes no fuckin sense to me
I have a physics bachelor's and it's helpful when this stuff comes up, but I gotta tell you, there is not a lot of money in understanding black holes
I actually think all of that makes sense to me. Incredibly fascinating stuff, this has made black holes seem slightly less alien. And it's not like humanity is at all new to the idea of fundamental principles we thought we figured out actually being wrong.
That actually leads to the concept of plank stars, where once the mass reaches the planck length it rebounds
Interesting, I wasn't familiar with that term bc it was coined shortly after I studied this stuff but it seems to be referring to similar stuff to I described (the ideas behind it are older than the term itself).
I used to have existential dread as a kid about the possibility of a wandering black hole swallowing up the solar system.
Like the fact that it is technically physically possible and that we would not even see it coming and if we could we would have no way of doing anything about it still haunts me.
Another potential problem is a gamma ray burst. It will travel at the speed of light (duh) so no advance warning, and one aimed at us would destroy our atmosphere which would be very bad.
The hardest part to wrap your head around is the fact that the interior quite literally does not exist from your perspective, nor will it ever. From our perspective outside of a black hole, everything that has ever fallen into a black hole is not actually inside it yet, it is actually squashed up against the surface impossibly thin, asymptotically approaching the radius we observe as the event horizon. Due to time dilation, there is in fact no black hole yet; just a collapsing star paused in time approaching infinitely close to the moment where its mass is contained within its Schwarzschild radius. We can't observe these objects squished up against that boundary because the light they emit gets red shifted into infinity, but that's where they are and will remain forever.
But from the perspective of an object falling in, nothing special happens at the event horizon. It observes the flow of time to be as normal, and it simply becomes causally disconnected from the entire rest of the universe as it enters a space that does not exist for us.
I'm not exactly sure how black hole evaporation works into this, though. Just when you think you got something about physics understood, you realize you actually don't.
I'm not exactly sure how black hole evaporation works into this
Yeah I thought I was with you but then this doesn't make sense at all. If black holes can cease to exist then surely anything that was "frozen" at the event horizon should just get flung off into space
Hawking Radiation, I believe is the term for however something, uh... I guess escapes the black hole.
So, what, a black hole is like a cosmic grinder that just converts all that matter into hawking radiation ("instantly" from the perspective of the thing being destroyed) and nothing ever actually reaches the singularity?
Ask three physicists this question and you will get three completely different answers to it. This question is one of the biggest unresolved questions in physics.
It seems like maybe they do, but if so, then they're able to reduce matter from a complex state to a simple one, meaning they can reduce entropy in a closed system, which isn't supposed to be possible.
From my understanding, pairs of particles pop into existence everywhere in the universe, all the time. These particles have a negative and a positive charge, and they cancel each other out moments after popping into existence. However, these pairs of particles can pop into existence in a way that causes one of them to appear inside the event horizon of a black hole, while the other pops into existence outside of the event horizon. Over time, this ??? and the black hole evaporates.
The particle-antiparticle pair thing is an imperfect analogy. PBS explains it well here https://youtu.be/qPKj0YnKANw
But from the perspective of an object falling in, nothing special happens at the event horizon. It observes the flow of time to be as normal, and it simply becomes causally disconnected from the entire rest of the universe as it enters a space that does not exist for us.
Not quite true, the observer crosses the event horizon in finite time, but I believe they're capable of observing the end of the universe. But as you said, not sure how black hole evaporation effects this either.
When I was a kid an astrophysicist in my family explained black holes to me using a simplified model like this.
Imagine the fabric of space-time as a literal fabric, a trampoline. When you put a heavy object like a planet, or a bowling ball onto that trampoline it warps and distorts the shape of the surface. You can see how other objects will be attracted to that heavy object, how two heavy objects might be attracted to each other, and to some degree how an object might orbit around that heavy object, like one of those spinning coin funnels. If we imagine that bowling ball being much heavier, much denser, we can imagine how it will distort the fabric more and more, making its effect on other objects more dramatic, until eventually it is so dense and heavy that it tears through the fabric of that trampoline. Unlike the trampoline though, the fabric of space-time won't spring back when the ball tears through, and that heavy hole in the middle of the trampoline will continue to very dramatically affect other objects.
So it isn't that it has infinite density, but that it doesn't matter if it's denser than the point at which it tears a hole, it's still going to tear the hole either way. So it's more like the "speed limit" of density.
I'm not sure exactly how accurate that is, but to an 8-year-old Emma it made sense and was a lot less scary than the perception that black holes were some sort of a "glitch in The Matrix"
Imagining spacetime as something which can be torn by a star getting too thicc does not make the situation any less scary
Help, I'm trying to peacefully orbit the barycenter, but I'm dummy thicc and the mass of my accretion disk keeps accelerating my collapse
Still the most terrifying way to die I can imagine is falling into a supermassive black hole.
On a regular stellar mass black hole, the point at which it rips you apart atom-by-atom due to the difference in force being exerted on one end of your body versus the opposite end by gravity (a process lovingly referred to as "spaghettification") exists outside the event horizon, so you're dead long before you reach the point of no return. Still horrifying beyond measure, but at least it's a quick death.
On a supermassive black hole, however, the event horizon is so obscenely massive that you hit it before you get spaghettified, which means someone falling into one could theoretically fall past the event horizon without dying first and indeed might actually die of dehydration/starvation before reaching a point where gravity tears you apart if it's big enough. What would you experience? Would the neurons in your brain just stop working from physics breaking down, or would you exist in an infinite plane of pure darkness just wondering when it's going to end with no warning, or something else entirely?
I've been stressing like this almost non stop since my mom got diagnosed with cancer. I don't need a black hole to be horrified by dying
you couldn't fall into a black hole as you got close the gravity would spin you around and throw you away before you got close enough to be sucked near
I'm gonna go with you dying because your neurons dont work and call it a day.
The real worry is how will you time dialation as you approach the event horizion?
The way time functions near an event horizon is crazy.
Say your friend is jusy chilling near a black hole and you fall in.
From his point of view it would take an infinite time for you to fall in.
From your point of view it will be rather quick.
From your point of view however, even though you'll probably die before realizing it, the entire rest of time will pass outside of the black hole. You'll see stars be born and die, and the universe come to an end.
They're fucking weird man.
that would probably be the coolest way to die, hope they shoot me out into space next to one when i’m like 100
I think your body gets torn apart by tidal forces long before you get the cool relativistic effects
. Can't have anything cool.If the black hole is big enough you can survive past the event horizon. What rips you apart is the steepness of the gravity well, but the larger the black hole the less steep the well
Doesn't really bother me. They're just goofy stellar phenomena. Like there's a pulsar or something that acts like a relativistic flamethrower, firing out jets of atomic death that could sterilize planets lightyears away. No one would even know what hit them. Or like neutron stars? Or how the milky way and andromeda are going to collide in a few billion years? Space is wild but there's really nothing to do about it but sit back and grill.
Eh, the Andromeda and Milky Way colliding is going to be such a slow event that you wouldn't even notice it's happening.
I won't notice it because I don't have long-term plans to accommodate it into my own life 😌
firing out jets of atomic death that could sterilize planets lightyears away.
And that doesn't bother me either, if one of those hit us or the sun shit will go from everything's fine to instant death. Like visiting the Titanic in a fiber carbon submersible, either I get to tell a cool story lying about how cool the experience was, or I don't have nothing to worry about ever again.
Tho if the death ray hits Jupiter maybe we survive long enough for things to be fucked.
If it hits the sun, is the idea that the sun's explosion owns us and not merely that the sun is obliterated?
I googled it and there are low chances of the sun getting hit by a gamma ray large enough to make it explode, my bad
To be fair, we don't quite know if they have infinite density or not. Our understanding of physics breaks down at that point, so that's the only explanation we can give. But yes, black holes are very freaky.
It's shit that's so dense it might as well be infinitely dense since we really have no way of telling the difference, and it's not like it would really matter in a practical sense
We don’t have the theory to understand the inside of black holes. Spacetime itself seems to break down, so it may even be invalid to talk of a “space” inside a black hole. It’s best to talk about what we know for sure (black holes have “no hair”), which is entirely encoded on the surface of the black hole.
I dunno, the idea of a black hole doesn't seem too frightening to me from what I understand.
If the sun was replaced by a black hole of the same mass as the sun, the earth's orbit would remain the same, right? Aside from the change in temperature/electromagnetism, that is.
It's hard to understand and their gravity fuck with our understanding of physics, but there were things on earth that once were unknown and scary.
I don't want to be in a room with a black hole, but I think they're remote enough that we don't have to worry about them in our lifetimes.
But there's something about the existential dread that comes from feeling so small and powerless in our growing understanding of the universe.
Yeah, honestly, same, j'm'en calisse about a black hole. There are more slower, painful things to die from. But as a concept, it is morbidly fascinating.
"Hahahahahahahaha How The Fuck Is Chandrasekhar's Math Real Hahahaha Just Walk Away From The Notepad Like Close Your Eyes Haha"
In the movie Sorry to Bother You, one of the early scenes is the main character Cassius ruefully wondering about his tiny existence in the cosmos. I related to that scene, because we humans do feel unfathomably small and powerless to the potential of the universe. These kinds of things used to cause me a little bit of existential dread.
But this fixation on these forces that are so beyond our human capability occupy his thoughts because he is personally directionless. He hasn't yet found something to live for, or something which is significant enough to him to give his life meaning. So he considers himself a meaningless piece of space dust.
By the end of the movie, Cassius does find something more tangible, more immediately relevant, and very meaningful to him. It's his solidarity with the workers against the hyper-exploitative Amazon-esque company. It's his fight to have a decent life here on Earth. I read this as a commitment to solving solvable human problems rather than dashing yourself against the immutable wider universe.
The problems of the stars stop crushing his inner thoughts, because finds that he has real work to do that matters to him. And that's how I feel about it, now, too. I think the space stuff can be scary. It's mostly fascinating. And either way, it affects me little and is truly out of my control, so I shouldn't have to fear it.
In the movie Sorry to Bother You, one of the early scenes is the main character Cassius ruefully wondering about his tiny existence in the cosmos. I related to that scene, because we humans do feel unfathomably small and powerless to the potential of the universe
I don't get that why does the universe being big make you less significant. If you were twice as big would you be twice as significant
I don't get either school of thought because my life would be the same if every stat went dead tomorrow or an alternate universe version of me started killing people. I care about the things in my life specifically, not relative to some abstract "true meaning."
How the hell can there be a thing in this universe that has infinite density?
That's the craziest bit. We're not even sure it does. We can't see through the event horizon to see what actually does go on inside there.
Won't their gravitational pull give them away before they get anywhere near us?
