Black hole vs. Black hole, who wins?

[Chaos' lil bro Order]

Is there any theory that attempts to answer what would happen if two equally massive black holes collided?

Also, If one could isolate an entire galaxy like Andromeda, so that no external forces outside of its volume could interact with its contents, would Andromeda's core black hole slowly devour all surrounding galactic matter? Or would this matter simply hold orbit forever, or some other explantion?

thanks.

 

[mathman]

Is there any theory that attempts to answer what would happen if two equally massive black holes collided?

Also, If one could isolate an entire galaxy like Andromeda, so that no external forces outside of its volume could interact with its contents, would Andromeda's core black hole slowly devour all surrounding galactic matter? Or would this matter simply hold orbit forever, or some other explantion?

thanks.

If two black holes collide, they simply merge into one big black hole.

The question about a galaxy should be looked at independent of whether or not its massive center is a black hole or not. It is no diffferent from the question of the eventual fate of the solar system. In either case whether or not something falls in depends on it maintaining enough angular momentum. (for the solar system there is the extra problem of the sun becoming a red giant)

 

[james77]

Is there any theory that attempts to answer what would happen if two equally massive black holes collided?

I think that this situation would be very rare to actually observe i.e. where everything about each BH would be exactly the same or equal for a given period of time. There are two possible outcomes (a) (the most likely) they will simply merge and become one massive BH after a certain period of time due to the ever slightly weakening in the momentum of one of them with time (this could be due to the different physical composition of them and hence this would critically affect the momentum with of one of them with time) (b) They could at a certain distance from each other, remain for an infinitely long period of time close by, without ever actually merging, due to possible repulsion forces at the outer limits of each (c) (highly unlikely) Perhaps one of them could somehow "survive" in some new or diminished form by passing through it, like the storm spots on Jupiter that rotate in opposite directions, although I think this is very unlikely (Of course there's still a large amount of actual experimental data that we don't know about BHs)

 

[Katrex]

Well first of all two black holes coliding is sighly unlikly, but if it did happen what does "who wins mean?" What happens when two singularities conect? They probably just become one singularity infinatly small x 2 is sitll infinatly small.

as to galaxies colapsing on themselves with no external forces. I supose It COULD happen. But let's look at the with a realistic veiw of gravity, Just because there is nothing pulling things out doesn't mean its going colapse. Take the Earth and the sun, do you think if we removed Jupiter Earth would crash into the sun? No of course not, we still have the same total energy maybe our orbit would change a little but that's probably it.

As for galaxies as long as there isn't a colision things don't colapse the two masses orbit around their center of mass, asumedly a glalaxy acts in the same way the galaxy slowly spins((in terms of time not speed)) around its center of mass

 

[stevebd1]

While these 2 black holes are no where near equal (one of them a staggering 18 billion sol mass), I thought it would be of interest-

http://www.caha.es/18-billions-of-suns-support-einstein.html

see also-

http://www.astro.utu.fi/news/080419.shtml

http://space.newscientist.com/article/dn13166-biggest-black-hole-in-the-cosmos-discovered.html

http://www.skyandtelescope.com/news/13731992.html

Steve

 

[Chaos' lil bro Order]

While these 2 black holes are no where near equal (one of them a staggering 18 billion sol mass), I thought it would be of interest-

http://www.caha.es/18-billions-of-suns-support-einstein.html

see also-

http://www.astro.utu.fi/news/080419.shtml

http://space.newscientist.com/article/dn13166-biggest-black-hole-in-the-cosmos-discovered.html

http://www.skyandtelescope.com/news/13731992.html

Steve

very interestin, ty

 

[SarusVictoria]

If two black holes (though as unlikely as it may be) were to colide, they would most likely become nothing. Dew to the nature of a black hole, whitch is the destruction and consumtion of matter, two outcomes would occure.

1: Depending on if one of the black holes were larger and more powerful then the other, the less powerful and smaller of the two would be sucked in and become what matter becomes when entering a black hole...nothing.

2: Now, if both were the same size, had the same power, and could do the same damage, the outcome could be two different things:
A: They form together and become an evern more powerful and larger black hole.
B: They start to consume one another until there is nothing left but some left over matter from the outer parte of the black holes.

Now, I'm not an expert at all, I'm just a 20 year old military wife with a 1 year old daughter. But these things have always interested me. My ideas are only ideas, nothing more.[/FONT]

 

[Nabeshin]

Fairly confident no matter what the mass ratio between two black holes, a collision-event ultimately results in a merger with a black whole whose horizon is of greater or equal size to the sum of the previous two horizons.

 

[SarusVictoria]

...I have no idea what you said...remember, I'm just a military wife and mom...high school education only...

 

[chingkui]

what would we see as an outsider sitting far far away when the two collide?
For each BH, we see objects that fall into it takes infinite time to reach the event horizon. If the event horizons of the two BH touches, the objects that never quite pass the event horizons from our point of view would crash into each other, but it can't happen since the objects had long reach the BH center in some local frame. So what do we actually see? Also, does it take infinite time for them to merge as observed by us outsiders?

 

[DaleSwanson]

Dew to the nature of a black hole, whitch is the destruction and consumtion of matter, two outcomes would occure.

1: Depending on if one of the black holes were larger and more powerful then the other, the less powerful and smaller of the two would be sucked in and become what matter becomes when entering a black hole...nothing.

You seem to have a fairly common misconception about black holes, that they destroy matter. When anything falls into a black hole, matter, energy, or other black holes, it just adds to the mass of the black hole. Black holes are just very dense matter. The more mass they have the greater gravity they have. When some simply piece of matter falls into a black hole that mass is just added to the black hole increases in size slightly.

 

[Bernie G]

See the talk about merging black holes at:
https://www.physicsforums.com/showthread.php?t=226671

 

[Bernie G]

If two equal mass back holes merge, science and knowledge will be the winner, and gravity temporarily the loser. If two relatively small equal size black holes merge, at the point of contact of each BH's surface there will be no net gravitational force. If each BH contains something located at greater than 70% of the Schwarzschild radius, a large burst will occur. Probably about one of these BH-BH mergers occurs annually in other galaxies, and possibly they are observable and identifiable by a large gamma ray burst. The science of gamma ray bursts is growing rapidly so this might be confirmed in 10 - 20 years.

 

[vinayjain]

If two black holes collide, they simply merge into one big black hole.

The question about a galaxy should be looked at independent of whether or not its massive center is a black hole or not. It is no diffferent from the question of the eventual fate of the solar system. In either case whether or not something falls in depends on it maintaining enough angular momentum. (for the solar system there is the extra problem of the sun becoming a red giant)

can u please tell me that if there are only four dimensions exists in a black hole then which one of the black hole will be losing its other dimensions (what I understand till now is that there are 4 dimensions exists in a black hole i.e. 3 dimensions are of time and 1 is of space) but whole black hole has all the dimensions from outside.

Whose gravitational pull will be higher if they are of same mass.....

 

[Drakkith]

can u please tell me that if there are only four dimensions exists in a black hole then which one of the black hole will be losing its other dimensions (what I understand till now is that there are 4 dimensions exists in a black hole i.e. 3 dimensions are of time and 1 is of space) but whole black hole has all the dimensions from outside.

Whose gravitational pull will be higher if they are of same mass.....

Nothing will happen to dimensions in either black hole. Dimensions are not something that each object has individually. If dimensions were somehow different in a black hole, then both black holes would be equally different from the rest of the universe and upon merger they would be exactly the same except for being one bigger black hole instead of two.

 

[rgibbs421]

Wow, I really never thought I would get to the point of ever being able to ask a question on a thread this good but... Okay we got universe beginning and ending questions being asked here for the dreamers... So is gravity stronger then the mysterious energy causing the universe to still be expanding at an exponential rate? Say we take 10 then 20 and 40 and an entire galaxy becomes a black hole. Lay that theory on top of the hobbles deep field image and gravity loses up against the force behind the big bang.

 

[vinayjain]

Nothing will happen to dimensions in either black hole. Dimensions are not something that each object has individually. If dimensions were somehow different in a black hole, then both black holes would be equally different from the rest of the universe and upon merger they would be exactly the same except for being one bigger black hole instead of two.

Actually the thing is when two black holes collides either one of them will suck other one and in that case the black hole which gets sucked will be hitting singularity in other black hole but if both of them are of same mass and with same gravitational pull then what will happen at the time of there collision (which one will get sucked)?

 

[Drakkith]

Actually the thing is when two black holes collides either one of them will suck other one and in that case the black hole which gets sucked will be hitting singularity in other black hole but if both of them are of same mass and with same gravitational pull then what will happen at the time of there collision (which one will get sucked)?

I don't think this is true. Earth does not "suck" meteors to it, they simply fall into the atmosphere due to gravity. Both black holes would be attracted to each other and they would be both fall towards each other until they merged. Honestly they probably wouldn't even collide, at least not initially, but instead spiral around each other until the meet. What happens beyond the event horizon is beyond me.

 

[Drakkith]

Wow, I really never thought I would get to the point of ever being able to ask a question on a thread this good but... Okay we got universe beginning and ending questions being asked here for the dreamers... So is gravity stronger then the mysterious energy causing the universe to still be expanding at an exponential rate? Say we take 10 then 20 and 40 and an entire galaxy becomes a black hole. Lay that theory on top of the hobbles deep field image and gravity loses up against the force behind the big bang.

Current observations show that gravity is not strong enough to avoid the acceleration of the rate of expansion of the Universe. I don't even understand the rest of your question.

 

[PAllen]

One point is that in the very long run, two stellar mass objects closely orbiting (be they black holes, pulsars, stars, whatever) cannot maintain stability. Gravitational radiation will sap the angular momentum, and they will spiral towards each other. Thus, the answer to the original question is: if two black holes approach so as to get into a tight orbit (no need for collision), they will merge into a larger black hole, with immense gravitational radiation approaching merger.

 

[vinayjain]

One point is that in the very long run, two stellar mass objects closely orbiting (be they black holes, pulsars, stars, whatever) cannot maintain stability. Gravitational radiation will sap the angular momentum, and they will spiral towards each other. Thus, the answer to the original question is: if two black holes approach so as to get into a tight orbit (no need for collision), they will merge into a larger black hole, with immense gravitational radiation approaching merger.

that is what i am asking sir...that how can two objects merge together having there own gravitational pull...either they would have a collision or either one of them will fall down in other one and thus will lead to singularity as it will go closer to the centre...please suggest

 

[Drakkith]

that is what i am asking sir...that how can two objects merge together having there own gravitational pull...either they would have a collision or either one of them will fall down in other one and thus will lead to singularity as it will go closer to the centre...please suggest

I'm not sure you understand what merge means. If the moon fell to the Earth right now, it would effectively be merged to the Earth. They would become one object. When two black holes collide they will both fall into each other just like any other objects would. Note that a black hole is NOT a literal hole in space. It is simply an extremely dense object.

 

[vinayjain]

I'm not sure you understand what merge means. If the moon fell to the Earth right now, it would effectively be merged to the Earth. They would become one object. When two black holes collide they will both fall into each other just like any other objects would. Note that a black hole is NOT a literal hole in space. It is simply an extremely dense object.

like in this suggestion u have taken an example if at this point moon falls on Earth it will not merge it will collie with the ground surface of the earth

 

[Drakkith]

like in this suggestion u have taken an example if at this point moon falls on Earth it will not merge it will collie with the ground surface of the earth

And it will then merge with the Earth after this hypothetical collision.

 

[vinayjain]

And it will then merge with the Earth after this hypothetical collision.

exactly, they will have a hypothetical collision and same thing might happens when two black holes comes so close that they start orbiting each other and due to the gravitational pull they comes spiraling around each other and then they have a hypothetical collision and after that they will merge in each other.....but here there is a query of mine and it is when two massive black hole meet with such a collision then the outcome of this collision will produce lots of energy in the universe due to there density and speed or not? please reply

 

[PAllen]

exactly, they will have a hypothetical collision and same thing might happens when two black holes comes so close that they start orbiting each other and due to the gravitational pull they comes spiraling around each other and then they have a hypothetical collision and after that they will merge in each other.....but here there is a query of mine and it is when two massive black hole meet with such a collision then the outcome of this collision will produce lots of energy in the universe due to there density and speed or not? please reply

Mostly, you just get a bigger black hole (bigger horizon). What realistically happens inside the horizon is outside of known physics. As to whether the energy release during inspiral is remarkable depends on your expectations - I seem to recall computational GR scenarios where around 10% of the mass equivalent of the two black holes is released as gravitational radiation during the inspiral. But don't quote me on this.

 

[QuasarKing]

yeah.if two galaxy's black holes were to get too close during a galactic collision, they would merge into one larger black whole. But if these were worm holes, as some scientists are beginning to believe some black holes are, my theory is that:

They would cross paths as universal pathways and destroy each other in an incomprehensible release of transferring matter.

Please let me know if you know anything more about the function of worm holes or have anymore theories on this matter.

 

[Nabeshin]

yeah.if two galaxy's black holes were to get too close during a galactic collision, they would merge into one larger black whole. But if these were worm holes, as some scientists are beginning to believe some black holes are, my theory is that:

They would cross paths as universal pathways and destroy each other in an incomprehensible release of transferring matter.

Please let me know if you know anything more about the function of worm holes or have anymore theories on this matter.

Overly speculative and personal theories are not allowed here at PF. (And no professional scientists are beginning to believe what you claim)

 

[vinayjain]

yeah.if two galaxy's black holes were to get too close during a galactic collision, they would merge into one larger black whole. But if these were worm holes, as some scientists are beginning to believe some black holes are, my theory is that:

They would cross paths as universal pathways and destroy each other in an incomprehensible release of transferring matter.

Please let me know if you know anything more about the function of worm holes or have anymore theories on this matter.

Your perception might be true but,

Please tell me when there are two objects with such a high magnitude of gravitational pull comes closer then how will they going to transfer particles amongst them...Let us take a scenario of Earth and moon as taken by drakitt in previous replies, if right now moon falls on Earth will they both going to destroy each other or after hypothetical collision they will going to merge and if there could be a scenario in which they both will destroy each other then please tell me how they will going to do so...

 

[Bernie G]

Here's my thoughts. If 2 black holes "meet", the one that is much larger will absorb the smaller, like a frog eating an insect. Gulp, just goes down. But if 2 approximately equal size black holes meet its a different situation. To explain:

I think there’s a lot of confusion out there about black holes, mostly caused by so many people repeating the illogical argument that black holes are a point singularity. They use the incorrect argument that anything within the event horizon (Schwarzschild radius) must have energy greater than mc^2 if it is not to proceed to the center. This is getting facts backwards. The maximum gravitational energy of a star is (0.6GM^2)/R. If ALL a star’s energy goes into creating pressure, that energy would equal Mc^2 maximum. Setting Mc^2 = (0.6GM^2)/R results in the minumum radius R for anything, or any star, including the star in a black hole, of R(min) = (0.6GM)/(c^2). This is 30% of the Schwarzschild radius. Any smaller radius would mean the gravitational energy would have to exceed Mc^2.

Actual stars in nature have density profiles of about 1/(r^2), resulting in a gravitational energy of almost exactly (1.0GM^2)/R, or simply (GM^2)/R. And if all (or almost all) the mass inside a black hole were to go “relativistic” (I hate using that term), the total energy creating pressure would be (Mc^2)/3. The viral theorem, which is used to calculate the size of gravitational objects, says the energy creating pressure equals half the gravitational energy, or (Mc^2)/3 = (GM^2)/2R. This gives the radius of a star inside a black hole of R = (1.5GM)/(c^2), which is 75% of the Schwarzschild radius. It doesn’t matter what this star in a black hole is made of, quark matter, radiation, whatever; that's the size. Other basic math shows that the core density of a resulting black hole is about 20 times the core density of a neutron star, and the core pressure of the black hole is about 50 times the core pressure of a neutron star (of a few solar masses). Nothing profound or unrealistic about this. Maybe I shouldn't bother mentioning this, but also, if the star inside a black hole has an “atmosphere” of radiation, it would be small and insignificant and would not affect the above calculations. This hypothetical radiation wouldn’t come anywhere near the Schwarzschild radius and would be contained in much the same way the Earth contains its atmosphere.

An interesting result of the above is if two EQUAL mass orbitting black holes merge, there can be a huge ejection from them or even annihilation of the 2 black holes. Hmmm. Its only a matter of time before black hole mergers will be observed. Let's hope some observed mergers are of equal sized ones.

Finally, I don’t know why so many people use the Tolmann Volkov equation for a black hole. Not only does it give the wrong answer (neutron star collapse at 0.7 solar mass), but its conclusion of infinite pressure at the Schwarzschild radius is kind of obvious nonsense. But I do agree with Tolmann Volkov that the contents of a black hole can be analyzed as a gas, but one where the "gas" pressure P = (rho/3)c^2. Sorry for the length of this. If anyone has any questions on the above email Berniepie at aol.com or ask here.