First proof that "plunging regions" exist around black holes in space
ox.ac.uk
ox.ac.uk
From an outside observer they never cross the event horizon, due to the time dilation mentioned by the other comment.
Doesn't that imply that if we look at a black hole from a safe distance, the event horizon will appear to be a cluttered frozen motionless ring, full of all the stuff that is in the process of falling in but which from out point of view, never will?
Also don't forget even if you freeze forever as viewed by an external observer, the blackhole is growing, and will at some point consume everything that had previously fallen in.
You won't actually see the frozen photons though, just the ones before it. Once you see them, though, the image on the horizon is gone.
An outsider will see in-falling objects slow down, redshift, and never cross the horizon; but if you're falling in, this happens in finite time, you don't get to see the universe rapidly age, the black hole doesn't evaporate from Hawking radiation before you reach it.
From the viewpoint of the one falling in, you just fall in and cross the horizon without noticing.
Does make you wonder if time dilation gets so extreme, could another black hole wonder by, offset the gravity of the black hole, and let you escape. Even if it takes a billion years.
This could even be the most likley scenario, since ultra massive black holes eats vast amounts of smaller over the course of billion years.
I don't know what would happen if two event horizons overlapped briefly, as two black holes passed by each other at significant speeds. That's definitely above my paygrade :P
The trick is can a blackhole approach quickly enough to catch you as you keep dropping as you past horizon. Normally I'd say no, but the time dilation significantly complicates things.
It's far from obvious that just because the event horizons (which is just a mathematical concept and a 3D area of space) should control the trajectory of the singularity.
With two identical blackholes, with a event horizon of radius R, why should a singularity 2R away be unable to escape?
Really their entire playlist on black holes (and entire catalog for that matter) is worth a watch.
X-ray astronomers, how weird is it that they show their fits in physical space and not in instrument space?
You people are becoming zombies. Get away from your computer and interact with the world. Humans with profound intellect are producing the content that LLMs regurgitate for you.
We know that there are things that computers can flat out do better than humans, because there are limits to human brains. If computers continue to grow in power, then the fact that someday there might be an AI (actual AI, not LLM) which can come up with novel solutions is totally plausible. And if we go past that point and computers continue to become more powerful, then it's likely that the AI will continue to grow and become more powerful as well. And if the AI eternally expands its thinking capabilities with time, then it will inevitably surpass humans one day.
Do we need to get to that point to solve physics? Probably not. We're not at the limits of human ingenuity yet. But mentioning AI doesn't mean "I think LLMs in the next 3 months will solve everything!" either. No need to be so defensive about someone wistfully pondering about the limits of humanity.
I'm sorry, I'm not buying "superintelligence", outside of sci-fi plots. Even there it's kind of irritating deus ex machina stuff.
There's one thing machines have that we don't: time. A human-level AI would be better than a human because you can ask it to solve a problem for years on end without ever resting.
OK, so, maybe there are paradigm shifts to be reached that way, and maybe technology (familiarity with tools) will be crucial for these paradigm shifts which are the only way to understand certain new things intuitively. But, maybe this has been going on already, even before there were computers.
https://archive.org/details/Science_Fiction_Quarterly_New_Se...
Equally if not more annoying is the smug disdain of those who criticize it.
Even more annoying than that is people too caught up in "the world" and "serious matters" to read some sci-fi.
Let's be clear: what we have today is LLMs. Not superintelligence. When people drool over the promise of superintelligence, to the exclusion of curiosity about the problems we intelligent humans can solve, they've bought into a thought-terminating utopian fantasy. That's a dead brain, that will not help humanity progress. Zombies.
Superintelligence, should it ever arise, is my enemy. The disdain that I have for its adherents is born of self-preservation.
edit to add clarity regarding my admonition to experience "the world": whoever receives all of their knowledge from computer sources is readily replaced by an automaton with access to the same. Those of us who are curious about the world around us are capable of making observations yet to be recorded in electronic form. Be curious, my friend, or succumb to zombiehood.
Unfortunately your view is altogether tiresome and much harder to scroll past than the juvenile LLM excitement because it could actually do some real harm in the long term. No 'The Terminator" was not a documentary, nor was "The Matrix" nor even is your favorite episode of "Black Mirror".
Watts is far more eloquent than I could ever be on this subject matter. I highly recommend this article in The Atlantic by him and if you havent picked up any of his work I highly recommend pretty much anything hes ever written.
https://www.theatlantic.com/ideas/archive/2024/03/ai-conscio...
I criticize blind techno-doomerism for its use of clanky old worn out cliches from the sci-fi of last century. I criticize LLM bros for being naive and blinded by advertising. Both groups completely misunderstood the relevant sci-fi from this century, if they actually bothered to read any.
Sometimes between the rabid hype-bros and the holier-than-thou doomers you can find actual conversation about the nature of human interaction with theoretical future machine intelligence, how LLMs relate to that and the technical aspects of creating such a thing. Its rare but it is out there.
Hope for the best, prepare for the worst.
I don't know the chemistry necessary to turn crude oil into any plastic, I don't know how to use a Lagrangian, I tried and failed to learn group theory (I've only got the basics, and I'm not confident about them), and I've still only got a toy model of special relativity (which is supposed to be the easier one) — and yet, not only are those all still useful, the four colour theorem is useful even though it's a non-surveyable proof: https://en.wikipedia.org/wiki/Non-surveyable_proof
We passed that limit ages ago. The underlying technology used to do so is called "writing", which is what allows for things like libraries and letters / email and personal scratchpad notes.
Or maybe spin it fast enough so the singularity is visible.
this doesnt precisely follow. observation or experiment is possible from within the event horizon, although this might limit plausible venues for publication
Not sure about the inner horizon, just saw a discussion of the paper for a spinning black hole recently, it described three distinct regions.
The discussion is more like, if we had infinitely resilient materials or biology, what could they observe and experience.
Observe? Nothing, once you're inside the event horizon, right? The event horizon isn't a solid wall, it's just the point at which light can only move further inward, never outward. So even inside the event horizon, we still can't observe anything further in.
The same is true for black holes. A rocket or a human diving into a stellar mass non–spinning black hole would be “spaghettified”; they would be broken up into a thin stream of debris as they crossed the Roche Limit before they crossed the event horizon. But they could cross the event horizon of a much larger black hole, such as a supermassive black hole at the center of a galaxy.
In fact, if the black hole were massive enough then the gravitational field near the event horizon would be so mild as to be Earth–like. If you were to stuff all of the mass of three or four Milky Way–type galaxies into one black hole, you could build an actively–stabilized structure around the black hole to create a livable environment of truly insane proportions with Earth–normal gravity. Look up Birch Worlds sometime.
Which was also a rocketship into the future, moving you super fast towards the heat death of the universe?
It might seem like this costs you a lot, since it halves the amount of time you can live near your black hole. However, the lifetime of that black hole will be somewhere between 10¹⁰⁰ and 10¹⁰⁶ years, which is pretty insane even if you only get to use half of them. Furthermore, this is many orders of magnitude longer than the lifetime of a galaxy, so your civilization could potentially outlive everything else in the universe. Large stars burn out the quickest, but with black holes it is the other way around: small black holes evaporate the soonest. You might think that storing hydrogen in brown dwarf planets for use in fusion reactors would power a civilization for a long time, but fusion reactors are surprisingly inefficient. A civilization built around a rotating supermassive black hole can take advantage of the Penrose process to extract more usable energy from the same mass than the fusion reactors would.
Even more fundamental: you'd need infinite fuel to hang out forever just outside the event horizon — once you're inside, the direction of the singularity is "future" not "forwards", so you can't resist getting there with any form of propulsion any more than you can resist getting to next Thursday with any form of propulsion.
I don't know how near the event horizon a safe orbit can be?
In fact, I know that as a local observer falling into a black hole you can still see some of the outside world after falling into the event horizon (by looking "behind you"), you just can't send anything back. This also seem to contradict the statement that all paths point inside (or I may misunderstanding something).
Edit again: I did some research and it looks like that while parent's comment may be true for simplified model of a black hole, it is conjured to be possible for rotating black holes where you can stay inside. Also Google "penrose diagram kerr black hole" for some weird physic if you want to follow this rabbit hole. Keep in mind that I'm not a physicist and this is my understanding after 40 minutes of watching YouTube and Wikipedia.
All paths inside the event horizon lead to singularity. Full stop. This is reinforced by the Penrose diagrams you mention.
https://en.m.wikipedia.org/wiki/Innermost_stable_circular_or...
For spinning blackholes not to much. The singularity turns into a ring, the center of which the gravity cancels out.
Recent Veritasium video: https://www.youtube.com/watch?v=6akmv1bsz1M
Spinning blackholes (Kerr) of are quite complicated in comparison. They have an outer ergosphere, inner ergosphere, outer event horizon, and an inner event horizon. Also the singularity is no longer a point, but a ring.
A quote from the Ring_singularity link below:
An observer crossing the event horizon of a non-rotating and uncharged black hole (a Schwarzschild black hole) cannot avoid the central singularity
This is not necessarily true with a Kerr black hole. An observer falling into a Kerr black hole may be able to avoid the central singularity by making clever use of the inner event horizon associated with this class of black hole.
More info at:
https://en.wikipedia.org/wiki/Rotating_black_hole
https://en.wikipedia.org/wiki/Ergosphere
https://en.wikipedia.org/wiki/Ring_singularity> Now my reply to instrumentalism consists in showing that there are profound differences between "pure" theories and technological computation rules, and that instrumentalism can give a perfect description of these rules but is quite unable to account for the difference between them and the theories.
I think that's the right quote, Popper often lets me down when I want something terse and uncomplicated.
I would direct you to the holographic principle and the AdS/CFT correspondence. Because current theory suggest that the information that falls into a black hole is not lost and can be recovered (resolving the information paradox). Similar to as we can deduce the inner workings of the sun, from the information it emits, we could be able to deduce such information from hawking radiation in case of black holes.
https://en.m.wikipedia.org/wiki/Kruskal–Szekeres_coordinates
We just don't know enough about black holes to say for sure that the insides can not be studied in some manner. That's kind of why a theory of quantum gravity is so relevant, without it, the inaccessibility of the inside of a black hole remains at odds with key components of quantum physics.
Eg The current theory is that black holes release Hawking radiation, and studying that over the lifetime of the black hole might reveal information about the matter that went in. Understanding how this information is encoded could reveal things about the inside. Other possible explanations are that near the point of evaporation, when the black hole shrinks down to a size where quantum effects dominate, the information within becomes accessible, which could again allow potentially studying the inside.
Edit: I forgot to add in my original post that there's also just the possibility that the mechanism by which this paradox is resolved still hides the inside.
Health and safety gone mad!
Weirdly, it's hard to actually find information about this using the phrase "plunging region", as if you search for it everyone is currently regurgitating the strange Oxford press release wording of "safely". Which is an ironic turn of phrase because the result of the plunge is falling into a black hole. Though I think they probably mean that the circular orbit itself would be safe, not that the particle is falling in deliberately to avoid orbiting in some unsafe manner within a circular orbit!
But the Wikipedia article is actually pretty clear: https://en.wikipedia.org/wiki/Innermost_stable_circular_orbi.... So closer than 3 Schwarzschild radii, you can in theory have an circular orbit instantaneously, at a speed lower than light (until the photon sphere at 1.5Rs, where you have to orbit at c). If it was Newtonian rules, you could just orbit here. But because spacetime is warped inwards, anything actually in such an orbit will tip off the circular orbit and into a lower orbit, where it tips inwards and so on, into an inward spiral.
It seems a bit like one of those coin spiral games/charity boxes where the coin spirals down a curved cone-like funnel into the central hole. Even a coin injected tangentially eventually falls in, because the continously curved inward slope of the surface always makes the coin turn inwards and resists a stable orbit (even if it had no friction or air resistance).