4 ms·

Not a physicist, but isn't the whole point of black hole that they can grow. The way I picture it, is once you reach the black-hole state, there is a regime ch

Not a physicist, but isn't the whole point of black hole that they can grow. The way I picture it, is once you reach the black-hole state, there is a regime change which make it more easy to gulp matter in. I guess how big and how fast it grows depends how much mass there is nearby to concentrate. Once formed they tend to an equilibrium with their surrounding dictated by the balance mass-in/evaporation-out.

SiempreViernes 7y ago
Not really: (stellar) black holes have less mass than whatever object they were born from, and the mass is the only way by which they interact with matter. It's true that they don't have a stellar wind that pushes gas away, but they are born in the void left by their progenitor star, and once they start accreting there will be radiation pushing things again.
- Retric 7y ago
  That accretion disk represents constant growth via new mass. So, either way the black hole is is sucking up mass faster than a star.
  - SiempreViernes 7y ago
    No, most black holes have no visible accretion, and of those that have all have variable emission, meaning variable accretion rates. Black holes are not constantly growing.
    - Retric 7y ago
      We are not talking about rapid growth but... Hawking radiation for a 1 solar mass black hole represents less than 1 atom of material lost per billion years (~10^67 years vs ~10^57 atoms) They gain more than that even without a noticeable accretion disk inside our current galaxy. It’s only very very long time frames after black holes collect this material that they start losing mass on average.
theandrewbailey 7y ago
A black hole is a... hole, in terms of gravity[0]. Things fall into it. Unless you're not in a stable orbit, or being washed into it by gas (like water going down a drain), it's not going to 'suck' you into it. [0] https://i.stack.imgur.com/ZUKsw.png https://i.stack.imgur.com/ZUKsw.png
- GistNoesis 7y ago
  Yes I was aware of this misconception, but I was thinking that there could be strange effects, like tide effect ripping away the stars passing nearby. I was also thinking of the possibility of the hole getting wider transforming once stable orbit into non-stable one which will end-up inside the black hole. From what I've gathered, evaporation seems to be a really slow process. So I figured that it only gets bigger. The remaining question is how fast. We know there are very big black holes, though they were formed when conditions were different. I was wondering if there were possibility of a small one slowly by accretion growing into one, and was thinking maybe that if you are already very close to the black hole limit, maybe the neighborhood is also crowded and you could start a snow-ball effect. There is also the dark-matter/dark-energy issue if it exists, when you are a neutron star, you can pass freely but once a black hole you should collect it as you go.

SiempreViernes 7y ago

Not really: (stellar) black holes have less mass than whatever object they were born from, and the mass is the only way by which they interact with matter. It's true that they don't have a stellar wind that pushes gas away, but they are born in the void left by their progenitor star, and once they start accreting there will be radiation pushing things again.

Retric 7y ago
That accretion disk represents constant growth via new mass. So, either way the black hole is is sucking up mass faster than a star.
- SiempreViernes 7y ago
  No, most black holes have no visible accretion, and of those that have all have variable emission, meaning variable accretion rates. Black holes are not constantly growing.
  - Retric 7y ago
    We are not talking about rapid growth but... Hawking radiation for a 1 solar mass black hole represents less than 1 atom of material lost per billion years (~10^67 years vs ~10^57 atoms) They gain more than that even without a noticeable accretion disk inside our current galaxy. It’s only very very long time frames after black holes collect this material that they start losing mass on average.

theandrewbailey 7y ago

A black hole is a... hole, in terms of gravity[0]. Things fall into it. Unless you're not in a stable orbit, or being washed into it by gas (like water going down a drain), it's not going to 'suck' you into it. [0] https://i.stack.imgur.com/ZUKsw.png https://i.stack.imgur.com/ZUKsw.png

GistNoesis 7y ago
Yes I was aware of this misconception, but I was thinking that there could be strange effects, like tide effect ripping away the stars passing nearby. I was also thinking of the possibility of the hole getting wider transforming once stable orbit into non-stable one which will end-up inside the black hole. From what I've gathered, evaporation seems to be a really slow process. So I figured that it only gets bigger. The remaining question is how fast. We know there are very big black holes, though they were formed when conditions were different. I was wondering if there were possibility of a small one slowly by accretion growing into one, and was thinking maybe that if you are already very close to the black hole limit, maybe the neighborhood is also crowded and you could start a snow-ball effect. There is also the dark-matter/dark-energy issue if it exists, when you are a neutron star, you can pass freely but once a black hole you should collect it as you go.