The discussion explores the theoretical implications of black hole collisions, particularly focusing on whether it is possible for black holes to eject mass or split into smaller black holes during such events. Participants examine various scenarios involving glancing impacts, event horizons, and gravitational waves, while referencing concepts from general relativity and speculative ideas from literature.
Participants express multiple competing views regarding the outcomes of black hole collisions, including whether mass can escape or if black holes can split. The discussion remains unresolved, with no consensus on the implications of overlapping event horizons or the nature of gravitational interactions in these scenarios.
Participants note limitations in understanding due to the complexities of general relativity and the speculative nature of some claims. The discussion highlights the dependence on numerical simulations and theoretical models, which may not provide definitive answers.
Hurkyl said:To rephrase as a weaker question: can a black hole, oddly shaped or not, ever split into two black holes?
hexexpert said:If two black holes have a glancing impact at extremely high velocity what happens?
Vanadium 50 said:They merge.
That's a speculation based on numerical simulations, I don't think there are any known exact solutions which can prove beyond a doubt that this is what GR predicts.kista said:http://www.scientificamerican.com/article.cfm?id=naked-singularities
In this article author mentioned that naked singularities can form as a result of collision of two black holes.
Why would it necessarily mean that? A naked singularity could have a mass equal to the sum of the two black hole singularities.kista said:That means mass can be ejected from a black hole as a result of collision.
But gravity is not a "force" in GR, so this kind of analysis isn't sound. You'd need a more detailed analysis of the spacetime curvature as two black holes collided to see if anything that was formerly inside an event horizon could find itself outside of it (I imagine the answer is no, since an event horizon always seems to be moving outward at the speed of light as measured in a locally inertial frame of an observer infinitesimally close to it).kista said:Because if black holes collide such that there event horizons overlap then mass in the superimposing region gravity would be much weaker two black holes pulling in opposite directions with almost same force, so this mass can escape or it may fall in anyone of the black holes.
In GR gravity actually curves spacetime rather than space, with freefalling objects following paths through curved spacetime that locally maximize their proper time--the bent-trampoline image of matter curving the fabric of space is just meant as a vague analogy. Curved spacetime is not so easy to visualize, and even if there was a region of spacetime near the midpoint of the black hole's centers which was close to flat, it might well still be surrounded by more curved regions that prevented the possibility of anything escaping. Anyway, visual analogies in this context probably aren't very trustworthy, we'd really need to do the math.kista said:In GR gravity curves space and matter moves just moves in it. Imagine a prticle on the event horizon. In the presence of one black hole space would be curved to only one side, But in the presence of 2 black holes space would be curved on both sides of the test particle and it would be in a sort of unstable equilibrium and would be able to go anywhere.
kista said:http://www.scientificamerican.com/article.cfm?id=naked-singularities
In this article author mentioned that naked singularities can form as a result of collision of two black holes. That means mass can be ejected from a black hole as a result of collision. Because if black holes collide such that there event horizons overlap then mass in the superimposing region gravity would be much weaker two black holes pulling in opposite directions with almost same force, so this mass can escape or it may fall in anyone of the black holes.
Isn't it lower potential that's associated with being deeper in a gravity well, not increased potential? And being deeper in a potential well doesn't necessarily mean increased curvature, I remember reading that the region of spacetime inside a massive hollow sphere would be flat, but the potential inside the sphere is lower than outside, so clocks inside the sphere would tick slower than clocks outside (see this thread).kev said:Although the "force of gravity" in the region between two nearby black holes is weaker, the gravitational potential is actually stronger in that region because potential is additive. Increased potential means increased curvature and time dilation in that region.
JesseM said:Isn't it lower potential that's associated with being deeper in a gravity well, not increased potential? And being deeper in a potential well doesn't necessarily mean increased curvature, I remember reading that the region of spacetime inside a massive hollow sphere would be flat, but the potential inside the sphere is lower than outside, so clocks inside the sphere would tick slower than clocks outside (see this thread).