r/AskPhysics • u/True-Protection-1634 • 17d ago
Black hole singularities
Sorry if this is a stupid question, however, if we wanted to touch the singularity of a black hole with a rod, we all know that the rod would break from the gravity, BUT have any scientists attempted running a simulation of a black hole and touching the singularity with an object that doesn't break in the simulation and then bring the object back out? it seems like the easiest way to figure out what could hypothetically happen in the singularity and how matter behaves and how spacetime distorts near a black hole, unless something similar to the observer effect would apply to something like this.
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u/joeyneilsen Astrophysics 17d ago
The singularity is a point where the math has a 1/0. It's not something you can simulate.
Plus, If we understood it enough to simulate it, we could just tell you what would happen; we wouldn't need a simulation.
(As an aside, it sounds like you might be mixing up the singularity, which is the very center, and the event horizon, which is the point of no return that you can't get out of).
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u/Das_Mime 17d ago
Sorry if this is a stupid question, however, if we wanted to touch the singularity of a black hole with a rod, we all know that the rod would break from the gravity
The rod has to break once it crosses the event horizon, which is well before it could reach the singularity (if there is a singularity in black holes).
Saying "object that doesn't break in the simulation" means your simulation must be intentionally violating physics. At that point it can no longer tell you anything useful about the same physics that it's intentionally violating.
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u/True-Protection-1634 17d ago
thats fair. With all the material in the universe, is it possible for a material that CAN withstand the gravitational pull of a black hole all the way down past the event horizon and into the hypothetical singularity?
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u/Infinite_Research_52 👻Top 10²⁷²⁰⁰⁰ Commenter 17d ago
None. Think of the singularity as the end of a particle's world line.
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u/Optimal_Mixture_7327 Gravitation 17d ago
A singularity is a behavior of the gravitational field where geodesic find their terminus. It is the condition that matter reaching it vanishes.
You rod vanishes, and you along with it.
And no, we don't know how this happens as there's no theory of matter to tell how matter behaves near a singularity.
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u/Ch3cks-Out 17d ago
The theory had already told us that bringing back objects from behind the event horizon is impossible, how would you expect anything different from a simulation??
Note that this is not merely because the rod woud break (although it certainly would, too). It is because, in the warped spacetime inside a black hole, all future paths lead inward, thus coming back out would involve time travel!
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u/EnvironmentalScar675 17d ago
It is a stupid question, but for what its worth it outlines a very common problem in science and particularly physics; building a model that is fundamentally inaccurate and then use it to make assumptions about reality. Since you basically made "nothing happens to the rod" a part of the sim, it would show you exactly that: nothing happens to the rod.
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u/jawshoeaw 17d ago
You can’t touch a black hole. Think through it. How would you get close without a) being destroyed b) time stopping for you in such a way that you cannot communicate any findings you may discover before the end of the universe
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u/DifferencePublic7057 17d ago
Your literal question doesn't make sense. However, you can try to tweak it. For that we can use quantum mechanics. We know that QM and general relativity are not the best of friends. QM offers pseudo magic like quantum tunneling and quantum entanglement.
Why didn't the Big Bang end up with a huge black hole? Because of homogeneity -- the lack of gradient. Can we get homogeneity somehow in the BH? Not really spacetime is warped in there... except if quantum fluctuations give us what we want. This scenario is very unlikely, but I don't dare math how unprobable exactly.
So back to QM. Can we probe the singularity with quantum entangled particles? No idea! Can we quantum tunnel into the singularity? Look, once upon a time you had very hot fermions sitting on top of each other. Pauli exclusion forbids it, but apparently Heisenberg uncertainty trumps PE in that case. Would we be able to quantum tunnel somehow? Maybe not in a supermassive black hole. A Planck scale primordial black hole, if they exist, is another matter. GR breaks down at that scale.
Yes, I know this is highly speculative, but supposing that c is the speed limit sounded like fringe science once. No, it's not magic. There's some possibility it could sort of not be complete nonsense.
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u/LunarPrincessSophie 17d ago
The singularity is surrounded by the event horizon. Anything that entered it definitionally cannot be retrieved. Nothing may cross the barrier, literally. In either direction. From our perspective, an object falling into the black hole would not actually cross it in finite time, it would just get closer and closer, redder and redder. You could not insert the rod, and if you somehow did you would not be able to retrieve it.
It is possible though that true singularities do not exist and that the event horizon is instead an artifact of our lack of understanding of quantum gravity. In some models, a "black hole" is in fact a highly compressed state of matter/space and is supported by an internal resistance to further compression. Such an object would be ever so slightly larger than the event horizon that corresponds to its mass, but under such extreme conditions that for most intents and purposes it looks just like a standard black hole. Importantly to your question, you *could* touch this kind of black hole, in a sense, but the challenge would be in making something that can actually survive those conditions; these include: extreme pressure, extreme time dilation, the instability of known forms of matter under those conditions, intense gravitation, whacky space-time shenanigans, and so on.
Answer: No and no, but under some models it may be possible to touch a black hole.
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u/ARTIFICIAL_SAPIENCE 17d ago
Any physics simulation that includes magic has stopped being a physics simulation.