Using the formula for black hole density, a black hole of this mass would have an average density about the same as the near-vacuum atmosphere of Mars(!)
That calculation of density is nice, but since we don’t know what’s inside a black hole, it doesn’t mean anything.
Passing the event horizon doesn’t mean you’ve reached the potentially ultra dense singularity, but it does mean you won’t escape.
agos 2 hours ago [-]
we don't know how the mass inside a black hole is doing, but we have a pretty solid understanding of the volume and the total mass of black holes
tlogan 19 hours ago [-]
And it would take 10 days from event horizon to the singularity.
somat 14 hours ago [-]
from which perspective? I have yet to wrap my head around it(this usually means I am wrong about something), but there may be no singularity because it takes matter an infinite amount of time to reach the center due to time dilation effects.
This is the origin of my favorite science fiction theory. (little to no actual science but you could write a fun space romp around it) If you get a large enough black hole where the tidal forces will not rip you to shreds instantly, you could just scoot across the event horizon right, now what happens? you can still move around, everything feels normal, but really you have lost half a dimension, everything "out" from the center is completely gone from the universe. Now the theory, back to our universe, What happened to time? why does time only go one way? we can accelerate and decelerate along the time axis, but can't reverse it. Where has our missing half of a time dimension gone?
GoblinSlayer 4 hours ago [-]
>To an external observer, an object falling into a black hole appears to slow down and never actually crosses the event horizon, seemingly freezing in time.
It takes infinite time to reach event horizon, not the center.
somat 3 hours ago [-]
Yeah, that is the tricky part. The problem is that black holes are eldritch interstellar cryptids, and for the most part physics gives up and goes to cry in the corner the minute you start asking about "what's in a black hole?"
But in this specific case, you get one odd conclusion. if it takes forever to enter a black hole. is it impossible for anything to pass the event horizon? It sounds like this is observation dependent. but from an external point of view you are unable to observe anything entering the black hole. and from an internal point of view, the universe will instantly age and die when you try and enter the hole.(and if hawking radiation actually exists you will see the black hole shrink and pop the instant you try and enter it) either way nothing is getting in.
Is most of the mass of the star that formed the black hole actually stuck in a time dilated shell just outside the event horizon? Or perhaps all the mass is eternally stuck collapsing. and never actually reaches the density required to pass the event horizon. is that another way to define the event horizon? the point where time stops.
Time dilation makes my head hurt.
tbrownaw 9 hours ago [-]
> but there may be no singularity because it takes matter an infinite amount of time to reach the center due to time dilation effects.
Wouldn't that just mean that the singularity is located infinitely far into the future?
nine_k 6 hours ago [-]
Isn't it another way of saying that the singularity is never going to exist?
idiotsecant 9 hours ago [-]
It's not quite true that everything feels normal. If I am standing with my feet toward the singularity, my hand cannot move above my head, the best it can do is fall toward the singularity slower than my head does. Especially at very slow speeds this has some very weird physical effects, not the least of which is the immediate impossibility of all systems that make you 'you' continuing to function.
lordfrito 49 minutes ago [-]
Is this true?
My understanding is that for extremely large black holes the tidal forces are negligible near the event horizon. So things should function pretty much the same other than you can't move in reverse and get out.
If two rockets fall past the horizon at the same time, one accelerating forward towards the singularity, and the other accelerating backwards away from the singularity, then shouldn't the distance between the rockets increase, even though they are both moving inexorably forward?
If the tidal forces are low, I'd assume that my muscles are still strong enough to "slow down my hand enough" to move it above my head.
dustingetz 2 hours ago [-]
nor can you swivel your head to look backwards, as all the particles in your head are tidal locked in a falling trajectory towards the center
dotancohen 19 hours ago [-]
How so?
proteal 18 hours ago [-]
The black hole has two conceptual parts - the event horizon and the singularity. The event horizon is a one-way imaginary shell where once you pass it, you will end up at the singularity which is a point at the center of the event horizon. It’s the hole in black hole. Because the radius of the spherical horizon grows linearly with mass, but the size of the hole is fixed at effectively 0, it allows for a bit of sightseeing on your way to impending doom if the mass of the hole is large enough.
reactordev 18 hours ago [-]
This is also the light barrier where light can no longer escape the gravitational forces (causing the blackness of the black hole).
Your “sightseeing tour” would be a kaleidoscope of light as it brushes past you on its way to the singularity.
lazide 11 hours ago [-]
Uh, that is the event horizon?
reactordev 9 hours ago [-]
Yup, you’re trapped, so is light, and as gravity bends you and everything around you into pretzels, you’ll see everything yet nothing, as even the light will escape your retinas, before they pop like little grapes.
Eventually your atoms will make their way to the center singularity.
kulahan 17 hours ago [-]
One of the more mind bending aspects of this is how the horizon becomes inescapable. The singularity is the only “forward” that exists anymore. You cannot conceivably go anywhere else. Every direction becomes “in”.
dustingetz 2 hours ago [-]
it is not that hard to understand, if you jump out of a plane, there is also a spacetime singularity in your future, the ground
kortinador 15 hours ago [-]
another way of saying it is that the singularity is a place in time, not in space. it's a place in your future, and you cannot escape your future.
in a black hole time and space get switched in a sense.
chatmasta 14 hours ago [-]
One could say the same thing about death (or life). Once you’re born, death is the only “forward” that exists. You can’t calculate its exact distance but it’s inevitable.
dur-randir 9 hours ago [-]
Hydras tend to disagree.
pasquinelli 15 hours ago [-]
space becomes time and the singularity becomes the future.
pizzathyme 12 hours ago [-]
Definitely a dumb question but I had read "a teaspoon of black hole is more dense than Mt Everest" or something like that.
The near-vacuum atmosphere of Mars seems very light...? What fundamental concept am I misunderstanding?
aw1621107 12 hours ago [-]
> but I had read "a teaspoon of black hole is more dense than Mt Everest" or something like that.
That sounds more like a description of the stuff neutron stars are made of. I don't think that description really works for black holes - how exactly do you take a teaspoon out of a black hole?
> The near-vacuum atmosphere of Mars seems very light...? What fundamental concept am I misunderstanding?
The linked Physics.SE answer does a decent job at explaining it, but the short of it is that for Schwarzchild black holes mass ~ event horizon radius, so if you define density as mass / (Schwarzchild volume) you get density ~ 1/(mass^2) - in other words, the more massive a black hole the less dense it is by that measure.
jfengel 11 hours ago [-]
You can't make a teaspoon of neutroniun, either. The neutrons would immediately drift off and quickly decay (half life about ten minutes). It's just a way of illustrating the density.
You actually can have a black hole with the volume of a teaspoon, and it's stable. It will eventually decay by Hawking radiation, but not for umpteen gazillion years until the CMB gets cold enough.
aw1621107 10 hours ago [-]
> You can't make a teaspoon of neutroniun, either. The neutrons would immediately drift off and quickly decay (half life about ten minutes).
Technically speaking that sure sounds like scooping out a teaspoon of neutronium to me. Nothing said it had to be stable :P
But in any case, I suppose what doesn't work for me is that when the teaspoon illustration is being used it's in the context of picking out some sample/subset of a larger whole - take a whole neutron star and examine the properties of this supposed representative part of it, same way one might scoop out some ice cream out of a container. While that's technically not totally correct for neutron stars since they don't exactly have a uniform density, I feel that it's usefully-close-enough compared to black holes, since as far as we know all the mass of a black hole is concentrated in a point at its center so your "scoop" is either going to get nothing or everything.
> You actually can have a black hole with the volume of a teaspoon, and it's stable.
Sure, but at that point I wouldn't use the wording "a teaspoon of black hole"; something more like "teaspoon-sized black hole" would be more appropriate (though to be fair that's still technically somewhat ambiguous).
rapnie 7 hours ago [-]
Saw some Youtube vid years ago about what happened if you accidentally dropped the content of your teaspoon on the carpet of your living room. Earth would be relatively fine for a long time afterwards was the gist, if I remember correctly.
lucketone 11 hours ago [-]
Black holes become less dense as they get bigger.
Radius is linearly proportional to the mass: r = 2GM/c²
(So volume grows faster than mass)
cma 8 hours ago [-]
Small black holes are light, a large black hole with the mass of our visible universe would have an event horizon larger than the visible universe, because the area, not volume, scales linearly with the contained mass.
physix 11 hours ago [-]
This reminds me of when I was a physics undergrad way back in the mid 80s. We used to spend nights drinking beer and hacking some simulations from the Computer Recreations section of Scientific American.
Once we wanted to simulate the dynamics of galaxies. I don'it think it was an SA article, but we did it the slow way by calculating the force on every star individually from each other star. It was excruciatingly slow and boring.
Then some time later, I don't recall where I picked that up, I updated the simulation to just model the force on each star coming from the galaxy's centre of mass.
I could simulate many more stars, have galaxies collide and see them spin off with their stars scattering around.
What struck me was that they looked like real galaxies we see out there.
I wasn't aware of the postulations made in the 60s/70s about there being supermassive black holes at the centre of galaxies, but to me, this simplified simulation was kind of like a smoking gun for that... from an 80286 IBM PC AT.
sebastiennight 11 hours ago [-]
If we're assuming that the galaxy is radially symmetrical, doesn't it immediately follow that the combined gravitational force on a given star is the same as if we applied the force from a combined mass at the center?
This wouldn't work for something like the Solar system with a very sparse distribution of mass, but at the galaxy level it seems right even without the presence of a black hole.
physix 10 hours ago [-]
Even when the distance between the centres of mass of two colliding galaxies become comparable to their size?
It's a long time ago, but what I remember was being fascinated by the shapes of the galaxies emerging from a collision under this centre-of-mass approximation, and that it created shapes we see out there. It was as if the main effect were a central mass in each galaxy dominating the dynamics.
ubercow13 6 hours ago [-]
Even the largest SMBHs mass is a minute fraction of their host galaxies' total mass so it is not the case that everything is just orbiting the SMBH.
BSOhealth 22 hours ago [-]
With all the lensing going on out there, is it possible for us to observe the light from our sun (and potentially our planet) billions of years ago?
A cool achievement would be, observe the moon/earth separation event(s)
throwup238 21 hours ago [-]
Theoretically yes but although this black hole is big enough to make that more realistic, the redirected light would be have lost so much energy we’d likely be unable to observe it. We’d need an orbital hypertelescope to even stand a chance. Even then we wouldn’t see the earth because it would be drowned out by the sun.
The bigger problem is all the dust and other stars in the way. I’m not aware of any black holes close enough that would have a direct path for the light to cross without being absorbed and scattered.
LeifCarrotson 20 hours ago [-]
The other problem is the angle at which the light must be redirected. The Cosmic Horseshoe is composed of two systems almost directly in line, the light comes from the farther system and bends infinitesimally around the black hole to come to us. I don't know if a 180 degree bend is possible.
Also, the foreground galaxy/supermassive black hole in the Cosmic Horseshoe is 5.6 billion light years away, so any light that could come from our solar system, go around the black hole, and come back to our hypothetical hypertelescope would be over 11 billion years old - almost triple the age of our sun.
Saggitarius A* in our own galaxy is, of course, directly in the elliptic and therefore badly occluded by dust, but it would be interesting to look at as it's only 27k light years away. In the absence of that pesky dust, it would give us a picture of the solar system as of the Paleolithic. Andromeda, at 2.5 million light years away, would give us 5-million-year-old light. There are other black holes in the Milky Way on the order of a thousand light years away which are not at the center of the galaxy but have masses comparable to or slightly larger than our sun, these are far closer (within a few thousand years) but have much smaller gravitational fields. Luminous intensity drops off with the square of the distance, but I'm not sure how the gravitational field strength affects the ability of a particular galaxy to bend light.
throwup238 19 hours ago [-]
> The other problem is the angle at which the light must be redirected. The Cosmic Horseshoe is composed of two systems almost directly in line, the light comes from the farther system and bends infinitesimally around the black hole to come to us. I don't know if a 180 degree bend is possible.
It is possible to get a deflection angle of 180 but under a few million solar masses, hitting the “sweet spot” in between the photon sphere and the boundary of the shadow would basically be a once in the lifetime of the universe type probability, if it were possible at all. At billions of solar masses that sweet spot become much bigger, but then those are much further away.
ghurtado 19 hours ago [-]
> almost triple the age of our sun.
In this insanely hypothetical scenario, would it be possible to see a sun before our sun? (In the same galactic vicinity)
stevenwoo 16 hours ago [-]
I was under the impression that our sun is not large enough to form the heavier elements on earth and this means supernova or collision of neutron stars had to be responsible for creating these elements, some of the stuff flying off this explosion formed our solar system, so we could see those progenitor stars.
21 hours ago [-]
chiffre01 21 hours ago [-]
How big would the diameter of this be ? Something like 8 light days ?
myrmidon 20 hours ago [-]
Sounds about right. Wiki has a correctly scaled picture with the two biggest known black hole event horizons and the solar system:
Interesting. Given that the horseshoe shape is due to gravitational lensing of one far off galaxy ~19 Gly away by another "only" 6 Gly away, wouldn't that mean that any motion of those galaxies, or our galaxy, would realign the lensing and alter the shape of the horseshoe?
So... how long before we see the shape change? How fast do galaxies move anyway?
AnimalMuppet 22 hours ago [-]
A bit off topic: Is there any theoretical upper limit on the mass of a black hole?
MurkyLabs 22 hours ago [-]
It doesn't seem like there's a limit to how big they can get just a limit to how quickly they can get bigger due to what's called the Eddington Limit which explains how matter falling into the black hole emits radiation and if enough radiation around the accretion disk builds up, it can overcome the pull of the black hole and push matter away, at least until enough matter is pushed away that the radiation levels fall back under the limit and matter starts falling in again.
qualeed 20 hours ago [-]
PBS Spacetime had an episode somewhat recently about a black hole which is growing at many (hundreds? thousands? I forget) times the Eddington Limit. And, as far as I remember, it isn't the only one to exceed the Eddington Limit - just the one with the record for how much it exceeded it.
I'll try to dig it up when I'm not at work (or if I remember the exact episode through the day).
orra 17 hours ago [-]
I remember this episode too. The answer is four thousand times bigger than the Eddington Limit. Blimey!
Importantly, the Eddington limit does not apply to black hole mergers, theoretically allowing as much growth rate as you're able to feed in from smaller black holes.
pixl97 16 hours ago [-]
This said, the final parsec problem isn't solved/understood. We know black holes do merge, but we don't understand what energy is being bled out of the system so supermassive black holes crash into each other in the timeframes we're seeing it occur.
allemagne 20 hours ago [-]
So then the only theoretical limit on black hole mass would just be how fast you can put matter in black holes and/or merge existing black holes versus how fast the universe expands?
MurkyLabs 19 hours ago [-]
I'm 100% an armchair physician so take my words with a grain of salt but it seems like according to the math there is no limit to how massive a black hole can get. There are limits on the size of how big and small things can get and how hot or cold they can get, the second part is pretty cool, Physics Explained on yt has a good video on it (he's got a lot of good videos) but I enjoyed this one on what the maximum temperature is in the universe: https://www.youtube.com/watch?v=NVlEQlz6n1k
ghurtado 19 hours ago [-]
> I'm 100% an armchair physician
Not to be that guy, but a physician is a doctor.
jfengel 11 hours ago [-]
Not to be cet homme, but in French a physicien is a physicist.
dotancohen 19 hours ago [-]
But that's not important right now.
andrekandre 11 hours ago [-]
shirley you cant be serious
ghurtado 17 hours ago [-]
Just pointing out a simple mistake.
In the time that it took you to type that response, you could have learned 10 new words.
I do it because I appreciate it when people do it for me.
That was the purpose of my comment. What was the purpose of yours?
throwaway81523 5 hours ago [-]
I heard a joke about a nerd who dies and finds himself in a very hot underground cavern. The devil is there, and says "Welcome to Hell! This over here is the lake of molten lava where you'll spend the rest of eternity". The nerd says "well actually, since it's underground it's called magma rather than lava". The devil replies, "um, you do understand why you're here, don't you?".
I try to remember that when I'm tempted to point out mistakes that are fine to overlook.
> [270B solar masses] is the maximum mass of a black hole that models predict, at least for luminous accreting SMBHs.
as well as:
> The limit is only 5×10^10 M [50B solar masses] for black holes with typical properties, but can reach 2.7×10^11 M [270B solar masses] at maximal prograde spin (a = 1).
However in the chapter before, it's stated:
> New discoveries suggest that many black holes, dubbed 'stupendously large', may exceed 100 billion or even 1 trillion M.
throwaway81523 20 hours ago [-]
There's a theory that the universe we live in is itself inside a giant black hole. No idea how it is supposed to have gotten so biig.
sesm 3 hours ago [-]
If you assume constant density, anything becomes a black hole at certain volume. The question is: is our universe big enough to be a black hole or not.
I know this article. It's citing a bunch of speculative hypothesis by mostly this one person which relies on something super exotic called Einstein Cartan theory. I stand by my statement. I even suspect the article was written by them.
I hate random links being thrown at me, because I don't know what you are trying to tell me. Perhaps you can spare a few key strokes.
For everyone else reading the thread, let me summarize. The article agrees with me:
> the entire observable universe exists within a black hole—except, that is, for all the evidence to the contrary
>....
> It does not seem likely that we live inside a rotating universe, let alone a black hole.
MarkusQ 19 hours ago [-]
You have elsewhere in this thread objected to people providing links without giving context, so I hope you won't mind being asked to unpack this claim a little. Why is it nonsense? If, as you say, it's principally pushed by one person, who is that, and why does that argue against it?
(I'm not thinking this is too much to ask; saying it's wrong might require empirical support, but the claim that it's "nonsense" should be easier to justify.)
mr_mitm 19 hours ago [-]
First of all, black holes have an interior and an exterior. Our universe only has an interior. Next, black holes have a singularity into which everything vanishes, or at least moves towards. Im our universe, everything moves away from a singularity. So if anything, it resembles a white hole more than a black hole. Also, our universe is expanding, whereas black holes shrink (unless matter falls into them, which can't happen to our universe because it has no exterior).
It really looks nothing like a black hole.
tejtm 17 hours ago [-]
Agreed, how do you feel about our universe being some sort of post evaporated BH-like-thing from a previous universe-like-thing?
pixl97 16 hours ago [-]
>Next, black holes have a singularity into which everything vanishes, or at least moves towards
I mean, everything in our universe does move towards something. The future.
abtinf 19 hours ago [-]
> giant
How would we know the size? Relative to what?
BurningFrog 22 hours ago [-]
So what happens if two such black holes collide?
msk-lywenn 22 hours ago [-]
Can black holes even collide? I guess their horizons can merge somehow... Probably a spectacular show.
I love to contemplate galactic-scale synchrotrons that accelerate supermassive charged black holes to collide at relativistic speeds. The thought never really goes anywhere, but I'm sure it'd be a spectacle to behold.
jfengel 10 hours ago [-]
It would be just about the only way we could get the data required to resolve the contradictions between the Standard Model and general relativity. The unification energy is simply stupendous.
Poking around those articles (and knowing nothing really), it is interesting to note a couple references to a 50B solar-mass limit for “luminous accreting black holes hosted by disc galaxies.” (In your Phoenix cluster link). I guess these ones are easier to spot, based entirely on the word “luminous.”
There are other larger ones out there, looming in the darkness.
pantalaimon 16 hours ago [-]
Those supermassive black holes are very old, from a time when the universe was much denser - they likely collapsed directly without any star formation
radicalbyte 17 hours ago [-]
There is this whole theory that the observable universe is inside a black hole.
nashashmi 11 hours ago [-]
So the upper limit is the weight of the universe.
bell-cot 18 hours ago [-]
Yes - but it's basically the same as the total mass of the universe.
EDIT: I believe the above could be incorrect - if the universe has too much electrical charge or angular momentum. (And some other cosmological properties, so you couldn't get around the charge & spin issues.)
Might there be a black hole astrophysicist in the house, to comment on this?
https://physics.stackexchange.com/questions/26515/what-is-ex...
Passing the event horizon doesn’t mean you’ve reached the potentially ultra dense singularity, but it does mean you won’t escape.
https://modern-physics.org/time-dilation-near-massive-bodies...
This is the origin of my favorite science fiction theory. (little to no actual science but you could write a fun space romp around it) If you get a large enough black hole where the tidal forces will not rip you to shreds instantly, you could just scoot across the event horizon right, now what happens? you can still move around, everything feels normal, but really you have lost half a dimension, everything "out" from the center is completely gone from the universe. Now the theory, back to our universe, What happened to time? why does time only go one way? we can accelerate and decelerate along the time axis, but can't reverse it. Where has our missing half of a time dimension gone?
It takes infinite time to reach event horizon, not the center.
But in this specific case, you get one odd conclusion. if it takes forever to enter a black hole. is it impossible for anything to pass the event horizon? It sounds like this is observation dependent. but from an external point of view you are unable to observe anything entering the black hole. and from an internal point of view, the universe will instantly age and die when you try and enter the hole.(and if hawking radiation actually exists you will see the black hole shrink and pop the instant you try and enter it) either way nothing is getting in.
Is most of the mass of the star that formed the black hole actually stuck in a time dilated shell just outside the event horizon? Or perhaps all the mass is eternally stuck collapsing. and never actually reaches the density required to pass the event horizon. is that another way to define the event horizon? the point where time stops.
Time dilation makes my head hurt.
Wouldn't that just mean that the singularity is located infinitely far into the future?
My understanding is that for extremely large black holes the tidal forces are negligible near the event horizon. So things should function pretty much the same other than you can't move in reverse and get out.
If two rockets fall past the horizon at the same time, one accelerating forward towards the singularity, and the other accelerating backwards away from the singularity, then shouldn't the distance between the rockets increase, even though they are both moving inexorably forward?
If the tidal forces are low, I'd assume that my muscles are still strong enough to "slow down my hand enough" to move it above my head.
Your “sightseeing tour” would be a kaleidoscope of light as it brushes past you on its way to the singularity.
Eventually your atoms will make their way to the center singularity.
in a black hole time and space get switched in a sense.
The near-vacuum atmosphere of Mars seems very light...? What fundamental concept am I misunderstanding?
That sounds more like a description of the stuff neutron stars are made of. I don't think that description really works for black holes - how exactly do you take a teaspoon out of a black hole?
> The near-vacuum atmosphere of Mars seems very light...? What fundamental concept am I misunderstanding?
The linked Physics.SE answer does a decent job at explaining it, but the short of it is that for Schwarzchild black holes mass ~ event horizon radius, so if you define density as mass / (Schwarzchild volume) you get density ~ 1/(mass^2) - in other words, the more massive a black hole the less dense it is by that measure.
You actually can have a black hole with the volume of a teaspoon, and it's stable. It will eventually decay by Hawking radiation, but not for umpteen gazillion years until the CMB gets cold enough.
Technically speaking that sure sounds like scooping out a teaspoon of neutronium to me. Nothing said it had to be stable :P
But in any case, I suppose what doesn't work for me is that when the teaspoon illustration is being used it's in the context of picking out some sample/subset of a larger whole - take a whole neutron star and examine the properties of this supposed representative part of it, same way one might scoop out some ice cream out of a container. While that's technically not totally correct for neutron stars since they don't exactly have a uniform density, I feel that it's usefully-close-enough compared to black holes, since as far as we know all the mass of a black hole is concentrated in a point at its center so your "scoop" is either going to get nothing or everything.
> You actually can have a black hole with the volume of a teaspoon, and it's stable.
Sure, but at that point I wouldn't use the wording "a teaspoon of black hole"; something more like "teaspoon-sized black hole" would be more appropriate (though to be fair that's still technically somewhat ambiguous).
Radius is linearly proportional to the mass: r = 2GM/c²
(So volume grows faster than mass)
Once we wanted to simulate the dynamics of galaxies. I don'it think it was an SA article, but we did it the slow way by calculating the force on every star individually from each other star. It was excruciatingly slow and boring.
Then some time later, I don't recall where I picked that up, I updated the simulation to just model the force on each star coming from the galaxy's centre of mass.
I could simulate many more stars, have galaxies collide and see them spin off with their stars scattering around.
What struck me was that they looked like real galaxies we see out there.
I wasn't aware of the postulations made in the 60s/70s about there being supermassive black holes at the centre of galaxies, but to me, this simplified simulation was kind of like a smoking gun for that... from an 80286 IBM PC AT.
This wouldn't work for something like the Solar system with a very sparse distribution of mass, but at the galaxy level it seems right even without the presence of a black hole.
It's a long time ago, but what I remember was being fascinated by the shapes of the galaxies emerging from a collision under this centre-of-mass approximation, and that it created shapes we see out there. It was as if the main effect were a central mass in each galaxy dominating the dynamics.
A cool achievement would be, observe the moon/earth separation event(s)
The bigger problem is all the dust and other stars in the way. I’m not aware of any black holes close enough that would have a direct path for the light to cross without being absorbed and scattered.
Also, the foreground galaxy/supermassive black hole in the Cosmic Horseshoe is 5.6 billion light years away, so any light that could come from our solar system, go around the black hole, and come back to our hypothetical hypertelescope would be over 11 billion years old - almost triple the age of our sun.
Saggitarius A* in our own galaxy is, of course, directly in the elliptic and therefore badly occluded by dust, but it would be interesting to look at as it's only 27k light years away. In the absence of that pesky dust, it would give us a picture of the solar system as of the Paleolithic. Andromeda, at 2.5 million light years away, would give us 5-million-year-old light. There are other black holes in the Milky Way on the order of a thousand light years away which are not at the center of the galaxy but have masses comparable to or slightly larger than our sun, these are far closer (within a few thousand years) but have much smaller gravitational fields. Luminous intensity drops off with the square of the distance, but I'm not sure how the gravitational field strength affects the ability of a particular galaxy to bend light.
It is possible to get a deflection angle of 180 but under a few million solar masses, hitting the “sweet spot” in between the photon sphere and the boundary of the shadow would basically be a once in the lifetime of the universe type probability, if it were possible at all. At billions of solar masses that sweet spot become much bigger, but then those are much further away.
In this insanely hypothetical scenario, would it be possible to see a sun before our sun? (In the same galactic vicinity)
https://en.wikipedia.org/wiki/TON_618
Event horizon radius would be about roughly 1000 times the distance between Earth/Sun.
https://en.m.wikipedia.org/wiki/Cosmic_Horseshoe
So... how long before we see the shape change? How fast do galaxies move anyway?
I'll try to dig it up when I'm not at work (or if I remember the exact episode through the day).
The episode is called “The NEW Ultimate Energy Limit of the Universe”. https://youtube.com/watch?v=0rzgYzbzq5Q
Not to be that guy, but a physician is a doctor.
In the time that it took you to type that response, you could have learned 10 new words.
I do it because I appreciate it when people do it for me.
That was the purpose of my comment. What was the purpose of yours?
I try to remember that when I'm tempted to point out mistakes that are fine to overlook.
> [270B solar masses] is the maximum mass of a black hole that models predict, at least for luminous accreting SMBHs.
as well as:
> The limit is only 5×10^10 M [50B solar masses] for black holes with typical properties, but can reach 2.7×10^11 M [270B solar masses] at maximal prograde spin (a = 1).
However in the chapter before, it's stated:
> New discoveries suggest that many black holes, dubbed 'stupendously large', may exceed 100 billion or even 1 trillion M.
For everyone else reading the thread, let me summarize. The article agrees with me:
> the entire observable universe exists within a black hole—except, that is, for all the evidence to the contrary
>....
> It does not seem likely that we live inside a rotating universe, let alone a black hole.
(I'm not thinking this is too much to ask; saying it's wrong might require empirical support, but the claim that it's "nonsense" should be easier to justify.)
It really looks nothing like a black hole.
I mean, everything in our universe does move towards something. The future.
How would we know the size? Relative to what?
https://www.youtube.com/watch?v=doS85Mh78Vc
This is what they look like when they merge, its pretty darn cool
https://scitechdaily.com/cosmic-heavyweights-collide-ligo-de...
There are other larger ones out there, looming in the darkness.
EDIT: I believe the above could be incorrect - if the universe has too much electrical charge or angular momentum. (And some other cosmological properties, so you couldn't get around the charge & spin issues.)
Might there be a black hole astrophysicist in the house, to comment on this?
(Sorry, I had to, with all the AI flood, I really was about to skip this info after the first 3 characters)
Hype is strong.