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I'm sure this is an oversimplified view, but doesn't it seem like, because black holes are more dense, they'd naturally tend to fall toward and gather around th

I'm sure this is an oversimplified view, but doesn't it seem like, because black holes are more dense, they'd naturally tend to fall toward and gather around the center of the galaxy? Sort of like how more dense objects tend to be found at the bottom of a pond? So then perhaps it makes a lot of sense that the galactic center would contain a lot of black holes.

Boxxed 9y ago
In a pond, you have the force of gravity (i.e., buoyant force) to do this sorting. This force doesn't exist in space, or at least not in a way that's analogous to the pond.
- davesque 9y ago
  Interesting. Can you provide any more details? Obviously the force of gravity exists in space. So what's a better way to describe the difference?
  - Boxxed 9y ago
    In a pond, gravity is uniform in all directions and not dependent on the distribution of objects -- everything is competing to get to the bottom.
rcthompson 9y ago
Imagine that our sun suddenly collapsed into a 1-solar-mass black hole. What would happen to the orbits of the planets? Nothing. The black hole would still exert the same gravitational pull as the sun did. The same is true if you replace all the planets with equivalent-mass black holes. Denser objects in an atmosphere or other fluid, where there is friction and buoyancy, will tend to sink to the bottom. However, if you're in the vacuum of space, there is no concept of "sinking". There is nothing to sink in unless you enter the atmosphere of a planet or star. However, maybe there is enough interstellar dust near the center of the galaxy to produce a non-negligible amount of friction over millions or billions of years.
- davesque 9y ago
  Mkay. I see my confusion. You need something like a fluid and also in a non-inertial reference frame which is under some force of gravity or acceleration. I guess a supermassive black hole such as Sagittarius A (assuming it exists) could provide a force of gravity. Then you'd need enough dust or something to exert pressure on the objects around it. It seems likely there's not enough of anything remotely like a fluid dispersed throughout the galaxy to have such an effect though who knows? I'm clearly no physicist :).

Boxxed 9y ago

In a pond, you have the force of gravity (i.e., buoyant force) to do this sorting. This force doesn't exist in space, or at least not in a way that's analogous to the pond.

davesque 9y ago
Interesting. Can you provide any more details? Obviously the force of gravity exists in space. So what's a better way to describe the difference?
- Boxxed 9y ago
  In a pond, gravity is uniform in all directions and not dependent on the distribution of objects -- everything is competing to get to the bottom.

rcthompson 9y ago

Imagine that our sun suddenly collapsed into a 1-solar-mass black hole. What would happen to the orbits of the planets? Nothing. The black hole would still exert the same gravitational pull as the sun did. The same is true if you replace all the planets with equivalent-mass black holes. Denser objects in an atmosphere or other fluid, where there is friction and buoyancy, will tend to sink to the bottom. However, if you're in the vacuum of space, there is no concept of "sinking". There is nothing to sink in unless you enter the atmosphere of a planet or star. However, maybe there is enough interstellar dust near the center of the galaxy to produce a non-negligible amount of friction over millions or billions of years.

davesque 9y ago
Mkay. I see my confusion. You need something like a fluid and also in a non-inertial reference frame which is under some force of gravity or acceleration. I guess a supermassive black hole such as Sagittarius A (assuming it exists) could provide a force of gravity. Then you'd need enough dust or something to exert pressure on the objects around it. It seems likely there's not enough of anything remotely like a fluid dispersed throughout the galaxy to have such an effect though who knows? I'm clearly no physicist :).