> "At the beginning of time and the center of every black hole lies a point of infinite density called a singularity"
my understanding was that this was d̶i̶s̶p̶r̶o̶v̶e̶n̶ mathematically incorrect:
- https://news.ycombinator.com/item?id=38636225
- sabine's take: https://www.youtube.com/watch?v=nz55jONtFAU
edit: disproven -> mathematically incorrect
PBS Space Time's take on Kerr's paper:
https://www.pbs.org/video/what-if-singularities-do-not-exist...
Echoing JumpCrisscross' sentiment, though. "Disproven" is way too strong of a word.
> my understanding was that this was disproven
To the extent anything in this discussion can be absolute, it's the wrongness of your statement. Nothing about singularities has been empirically proven (or disproven).
You don’t seem to be new around here, so this quote from this forum’s guidelines is more for the benefit of others
> When disagreeing, please reply to the argument instead of calling names. "That is idiotic; 1 + 1 is 2, not 3" can be shortened to "1 + 1 is 2, not 3."You’re right. My apologies to OP and y’all. Can’t edit, but the snark was uncalled for.
I don't see any name calling. Could you eplicitly state what the problem is?
We can empirically prove that gravitation cancels out in the gravitational center of an object, if we will dig into Moon.
What does this have to do with singularities? No one expects any kind of singularity anywhere around or in the moon.
Singularity is not possible at 0G, isn't?
> Singularity is not possible at 0G, isn't?
One divided by zero is a singularity. Singularity, mathematically speaking, means your math breaks. Calculus gets around this problem with limits. But there is absolutely nothing about physics that prohibits singularities, even gravitational singularities, in a zero G space because by definition a gravitational singularity per se has an undefined G.
Singularity means that at least some barions will be at the same place in the same time, which against nature of fermions.
Moreover, it hard to imagine that Higgs bosons will act at same place and time with same effectiveness.
So, I cannot believe in a singularity unless it will be physically demonstrated.
Sounds like you mean fermions. Bosons absolutely can occupy the same quantum states, look up the Bose-Einstein condensate.
Also, no one serious claims that singularities exist when taking quantum mechanics into account. It's completely unknown territory.
They’re mixing up barycentres [1] and baryons [2].
Anyway, I propose to dig tunnel to the center of the Moon with plasma cutters and make a lab there. IMHO, the result will be worthy.
As non-native speaker, it's hard for me to argue with native speakers (especially when I sick, tired, in army, and at war), and I refuse to use AI to translate, because I suspect that such messages will be automatically rejected by future archivists.
If they don’t doesn’t that imply that a superextremal black hole could exist since there would be no naked singularity whose observation is forbidden by any cosmic censorship hypothesis?
I wrote «barions», but yes, you are right, I meant «fermions». Fixed.
> Singularity means that at least some barions will be at the same place in the same time
The singularity in a black hole has no conception of baryons, hadrons or fermions. Those are quantum particles. The singularity is in general relativity.
Also, 0G doesn’t mean zero gravity. An object in freefall is still subject to gravity despite experiencing 0G.
(Side note: fermions can occupy the same place at the same time. They cannot occupy the same state. This seeming mathematic fuckery goes on to describe many real-world weirdos like neutron stars.)
If matter falling into a singularity never reaches it because time slows down infinitely as you approach, wouldn’t this be a physical representation of a mathematical limit from calculus? The actual literal 1d singularity never forms but it is approached infinitely close.
They are singularities in the framework of general relativity, i.e. while ignoring quantum mechanics. I think most people expect the right version of quantum gravity to make the singularities go away, but studying classical GR is worth it on its own, so it's often ignored like in this statement you quoted.
What if gravity is non-linear and thus collapses the wave function? I think Penrose has suggested gravity as an objective collapse interpretation. The measurement problem still hasn't been resolved, but we observe a classical world around us, despite the fact that decoherence simply spreads the superposition of interacting quantum systems to the world. Gravity could be what prevents the linearity of quantum systems from putting the entire universe into superposition.
Gravity is non-linear (as in: the Einstein field equations are non-linear differential equations).
That has nothing to do with the measurement problem. Also, the measurement problem is only a problem of the Copenhagen interpretation. It doesn't exist in the many worlds interpretation.
Gravity as in the actual force or field, not the current equations. You mentioned quantizing gravity, a few physicists like Penrose doubt it can be done. MWI is not a consensus, and there are more than two interpretations. Objective collapse theories have also been proposed, at least one involves gravity as the mechanism.
In the GR model of black holes, the singularity is at the end of time inside the hole, not the beginning.
I think the "singularity at the beginning of time" being referenced here is the one postulated before / at the instant of the Big Bang.
Ah, I see, I was parsing the sentence wrong.
Your first link goes to a 2023 arXiv pre-print that never landed in any journals as far as I can tell (could be wrong though). And there seems to be some controversy about whether Kerr's math shows what he says it shows.
This is the danger of trying to sensationalize science and putting any special weight on science influencers, especially ones who very often seem gung-ho about any story that challenges the status quo despite the evidence.
To be fair, it's written by literal Roy Kerr.
Sabine doesn't even say it's disproven, and the paper doesn't claim that it's disproven, it just claims that one of the earliest proofs that it was a singularity was incorrect. There's an important distinction there. If someone points out a flaw in a proof of the pythagorean theorem, that doesn't mean the theorem is disproved, it just means that the proof was wrong.
A more diplomatic and uncontroversial way to put it is that the event horizon is the only thing we have any evidence for.
We don't have evidence for event horizon. Black hole is a hypothetical object to begin with, it exists only in mathematics, what evidence.
Two event horizons, because gravitation cancels out in the center of a black hole.
ps. Energy is sucked up from the center by second event horizon, but matter is pushed inside, forming a dense and cool crystal, a solid foundation for second order effects to play.
That assumes there is gravity, or even universe, "inside" the black hole. We don't have any evidence of that.
Black holes are a prediction of general relativity. The same theory predicts that all properties of spacetime exist up until the singularity. You cannot simultaneously believe in black holes and some sort of discontinuation of spacetime before the singularity.
That is a theory that makes predictions, not evidence. As you may note in my comments above, I am speaking exclusively to evidence.
It doesn't make sense to talk about black holes outside the context of GR. What do you even mean by black hole if you can't describe it in the language of GR?
> What do you even mean by black hole if you can't describe it in the language of GR?
You’re right. But playing devil’s advocate, there are QM objects that look like black holes [1] as well as observations of a supermassive object at Sagittarius A*.
The parts of GR we trust in order to interpret the data from our instruments is trusted precisely because there is evidence to back up those parts of the theory. We have no idea if that theory holds on the other side of a boundary across which no causation can occur.
Occam's razor says that you must present a proof that they are not existing in a black hole.
> Occam's razor says that you must present a proof that they are not existing in a black hole
Occam’s razor absolutely doesn’t predict that the weird thing that breaks physics occurs twice and then precipitates a crystal.
Physics is fine, it just model, which breaks.
However, we can see that stars are eaten by black holes, and then can be partially released back years later, so it's proven that 1) «an event horizon» exists, 2) matter can pass the «event horizon» in both directions, 3) light cannot pass the «event horizon» in one direction.
I do not introduce a new physics, like a «singularity», without any evidence. Occam's razor is in my hands now.
> 2) matter can pass the «event horizon» in both directions
Where was this proven?
These are ejecta from the black hole’s accretion disk.
Of course, but it looks like this accretion disk was below the «event horizon», because speed is much higher, 50% of speed of light, instead of typical 10%.
> it looks like this accretion disk was below the «event horizon»
No it doesn’t.
> because speed is much higher, 50% of speed of light
Spin the singularity.
I’d love to see a source for the authors claiming they believe matter exited the event horizon. That’s literally Nobel prize groundbreaking.
> > it looks like this accretion disk was below the «event horizon»
> No it doesn’t.
It is, because of the silence before the sudden «burp». Something consumed all the radiation produced by the accretion disk. I know the only one possible solution: the «event horizon».
Astronomers says that they are not sure:
> "Black holes are very extreme gravitational environments even before you pass that event horizon, and that's what’s really driving this," Cendes said. "We don’t fully understand if the material observed in radio waves is coming from the accretion disk or if it is being stored somewhere closer to the black hole. Black holes are definitely messy eaters, though."
but I can use this as evidence that the center of black hole contains a dense and cold crystal. Why not?
Moreover, if fractal theory is right, then we are inside infinite number of black holes of increasing sizes (or other objects). But, if we are inside a black hole, why sky is black and space is cold then?
> I know the only one possible solution: the «event horizon»
Try the unstable region between the ISCO and EH.
> Astronomers says that they are not sure
They’re not sure where outside the EH.
> I can use this as evidence that the center of black hole contains a dense and cold crystal. Why not?
You’re bordering on trolling, but simply, it’s because the evidence doesn’t work.
The comment you're responding to didn't assert that it is proven, but regardless: https://en.wikipedia.org/wiki/Hawking_radiation#Emission_pro...
Hawking radiation is almost painfully constructed to avoid the problem of anything, even information, crossing back through the event horizon.
Layman opinion here: If a black hole forms, the point where it forms is an event horizon, but not a singularity. Then, while things get worse, it disappear from the universe.
So why would a singularity ever form? And what can't be formed, can't exist.
Cosmologist here, the event horizon is not a true singularity. There is a singularity in certain coordinates, but it goes away when doing a coordinate transformation. There is nothing physically strange going on at the event horizon. The physical singularity is only at the center.
I have the (layman) impression that there is no inside - that spacetime is so stretched around the event horizon that there is no spacetime beyond it.
But, then, I've never seen anywhere that the mass of the black hole (which is very much a real thing that exists in spacetime) is distributed over the event horizon, which would be at the biggest amount of mass a given region of spacetime can hold, and is not concentrated on a point with infinite density inside it.
black holes have an interior, you wouldn't notice if you passed the event horizon of a large enough black hole.
can confirm just delivered an amazon package in one
trying to find the PBS Space Time for that but meanwhile enjoy