6 ms·

A bit off topic: Is there any theoretical upper limit on the mass of a black hole?

cft 1y ago
https://youtu.be/EGzvGgNmaiY?t=58s https://youtu.be/EGzvGgNmaiY?t=58s
jameskilton 1y ago
Given things like https://en.wikipedia.org/wiki/TON_618 https://en.wikipedia.org/wiki/TON_618 and https://en.wikipedia.org/wiki/Phoenix_Cluster#Supermassive_black_hole https://en.wikipedia.org/wiki/Phoenix_Cluster#Supermassive_b..., probably not. Seems like you can just keep shoving mass into it.
- bee_rider 1y ago
  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 1y 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
MurkyLabs 1y 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.
- zamadatix 1y ago
  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 1y 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 1y 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 1y 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 https://www.youtube.com/watch?v=NVlEQlz6n1k
    - ghurtado 1y ago
      > I'm 100% an armchair physician Not to be that guy, but a physician is a doctor.
      - dotancohen 1y ago
        But that's not important right now.
tromp 1y ago
https://en.wikipedia.org/wiki/List_of_most_massive_black_holes https://en.wikipedia.org/wiki/List_of_most_massive_black_hol... shows the maximal theoretical limit as 270B solar masses.
- BurningFrog 1y ago
  So what happens if two such black holes collide?
  - msk-lywenn 1y ago
    Can black holes even collide? I guess their horizons can merge somehow... Probably a spectacular show.
    - ryandamm 1y ago
      That’s precisely what LIGO measures, the gravitational waves from black hole mergers (or neutron star mergers, etc).
      - bookofjoe 1y ago
        >Cosmic Heavyweights Collide – LIGO Detects Largest, Fastest-Spinning Black Holes Yet https://scitechdaily.com/cosmic-heavyweights-collide-ligo-detects-largest-fastest-spinning-black-holes-yet/ https://scitechdaily.com/cosmic-heavyweights-collide-ligo-de...
    - 20k 1y ago
      Disclaimer: This is my own work https://www.youtube.com/watch?v=doS85Mh78Vc https://www.youtube.com/watch?v=doS85Mh78Vc This is what they look like when they merge, its pretty darn cool
    - boothby 1y ago
      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.
bell-cot 1y 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?
radicalbyte 1y ago
There is this whole theory that the observable universe is inside a black hole.
- nashashmi 1y ago
  So the upper limit is the weight of the universe.

cft 1y ago

https://youtu.be/EGzvGgNmaiY?t=58s https://youtu.be/EGzvGgNmaiY?t=58s

Given things like https://en.wikipedia.org/wiki/TON_618 https://en.wikipedia.org/wiki/TON_618 and https://en.wikipedia.org/wiki/Phoenix_Cluster#Supermassive_black_hole https://en.wikipedia.org/wiki/Phoenix_Cluster#Supermassive_b..., probably not. Seems like you can just keep shoving mass into it.

bee_rider 1y ago
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 1y 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

MurkyLabs 1y 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.

zamadatix 1y ago
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 1y 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 1y 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 1y 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 https://www.youtube.com/watch?v=NVlEQlz6n1k
  - ghurtado 1y ago
    > I'm 100% an armchair physician Not to be that guy, but a physician is a doctor.
    - dotancohen 1y ago
      But that's not important right now.

tromp 1y ago

https://en.wikipedia.org/wiki/List_of_most_massive_black_holes https://en.wikipedia.org/wiki/List_of_most_massive_black_hol... shows the maximal theoretical limit as 270B solar masses.

BurningFrog 1y ago
So what happens if two such black holes collide?
- msk-lywenn 1y ago
  Can black holes even collide? I guess their horizons can merge somehow... Probably a spectacular show.
  - ryandamm 1y ago
    That’s precisely what LIGO measures, the gravitational waves from black hole mergers (or neutron star mergers, etc).
    - bookofjoe 1y ago
      >Cosmic Heavyweights Collide – LIGO Detects Largest, Fastest-Spinning Black Holes Yet https://scitechdaily.com/cosmic-heavyweights-collide-ligo-detects-largest-fastest-spinning-black-holes-yet/ https://scitechdaily.com/cosmic-heavyweights-collide-ligo-de...
  - 20k 1y ago
    Disclaimer: This is my own work https://www.youtube.com/watch?v=doS85Mh78Vc https://www.youtube.com/watch?v=doS85Mh78Vc This is what they look like when they merge, its pretty darn cool
  - boothby 1y ago
    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.

bell-cot 1y 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?

radicalbyte 1y ago

There is this whole theory that the observable universe is inside a black hole.

nashashmi 1y ago
So the upper limit is the weight of the universe.