Thread: Black Hole Question

There seem to be many galaxies on collision courses, and I've heard that most, if not all galaxies have a black hole at the center. My question is what happens when black holes collide?

Well, the thing is that we don't really know that much about the subject. Black hole-black hole and black hole-neutron star collisions are what's "in" in experimental physics today. What I think happens is that the accretion disk of one is stripped away by the other until they get pulled into each otherand become one larger black hole. But remember, this is just my opinion!

You can't begin to imagine how much I love you guys for asking awesome questions!

I'm not an adept on the subject of black holes, but from what I have read they effectively devour each other. They will orbit in long periods for quite a while as they grow closer together. This sometimes actually causes a black hole to be kicked out the galaxy altogether. But at some point the singularities do merge. Now this is what I have read, and just like Pelletier said, this is the IN ZONE of experimental/theoretical physics today. Black holes are, by default, where our current theories break down entirely, so we're not 100% sure as to what happens when two infinitely dense objects collide. Definitely something to look up as the years pass.

Oh, one cool thing. According to a paper published a while back, a physicist (whose name I cannot recall), suggested that if you two black holes were orbiting close enough and you could go all the way around the both of them (just outside the event horizon) then you would return to your origin before you left for your journey. This is because space-time would be so warped as to lose meaning in a lot of ways. Not sure if that paper was ever confirmed mathematically, though.

If one black hole did merge with another, would it be like two drops of water on a window "amoeba-ing"(technical term) to make a mega drop of water? From what I know about quasars(very little) i would think that there would be a possibility that if two supermassive black holes met one might get all "quasar-y"(another technical term) but instead up sparaying energy/matter from the poles it would be too much matter too quickly and pop like a balloon with too much air, and let out all the the matter it sucked up at once. That would be REALLY coool to see. Either that or I need to read up on quasars.

You could certainly think of black holes amoeba-ing together, since they would be merging into an even larger black hole. What's interesting, though, is that these black holes can create binary quasars, where both supermassive black holes are spewing material out into space. The black holes wouldn't pop, however, but when black holes are evaporating (something that won't happen for an un-godly amount of time), once they get to a certain point they effectively rupture and explode, spewing forth particles and energy that have been kept inside for eons. This is a hypothetical view, but to the best of my knowledge is pretty accurate.

...but instead up sparaying energy/matter from the poles it would be too much matter too quickly and pop like a balloon with too much air, and let out all the the matter it sucked up at once.

...once they get to a certain point they effectively rupture and explode, spewing forth particles and energy that have been kept inside for eons.

AWESOME! Kind of like one enormous mega-super-supernova? Except instead of a star's worth of material, 100 million stars' worth of material...
By the way, I would live a billion years just to see that. You've just made my day.

Heh. Glad to have made you happy.

Yeah, it's some interesting stuff. If you want a crash course, watch the show "The Universe" and look for the episode "Cosmic Apocalypse" (I think that's the title), and it goes over how black holes die and explode. It's catastrophic and amazing. This is why science is awesome: because reality is amazing.

I have a question of my own, though. Does anyone know whether or not a black hole would still be spinning? Since it is infinitely dense and effectively renders most frames of reference invalid, would it still obey the conservation of angular momentum? Anyone know about this one?

Originally Posted by jwluns

There seem to be many galaxies on collision courses, and I've heard that most, if not all galaxies have a black hole at the center. My question is what happens when black holes collide?

When black holes get within a certain proximity of each other the areas in between are in enough of a gravitational well that it creates an event horizon. M/D^2 so if two equal sized black holes came within 1 1/2 of their event horizon of each other they would combine into one massive BH. The other thing is that the combined momentum from the collision is conserved.

once they get to a certain point they effectively rupture and explode, spewing forth particles and energy that have been kept inside for eons. This is a hypothetical view, but to the best of my knowledge is pretty accurate.

I learned something today.

I thought the old theory said that when a back hole finally came to the end of its existence that it disappeared into nothingness and took everything (i.e. all information) with it, thus violating a commonly assumed tenet of science: that in principle complete information about a physical system at one point in time should determine its state at any other time. Basically, nothing is ever fully destroyed or disappears. An example would be if you were to blow something to smithereens, it's 100% theoretically possible to resemble it perfectly, because all matter of that "something" still exists, it's just in different place and possible forms. It's like playing a move backward. But Hawkins, created the "Information Paradox" that suggested physical information could "disappear" in a black hole, allowing many physical states to evolve into precisely the same state. Later he recanted and said that black holes just disappear into parallel universes along with all the information they've sucked up; universes where black holes don't exist, thus the information is still saved! Dead black holes in universes with no black holes. LOL. Anyway, after reading these posts and watching the videos posted, I can see I need to read up some more!

Peace and God's Blessings....

(for some reason my last reply didn't go through, so I have to re-type it)


Basically the "detonation" (that wouldn't be the proper term, though) of a black hole comes down to Hawking Radiation. Apparently the more a black hole evaporates, the faster it will do so, so it effectively "explodes" at the end of its life.