Black Hole Collisions

[geordief]

Is there anything unexpected that could arise from 2 BHs colliding at speed? Would this just be another form of a Black Hole merger or would this be  a (obviously just a thought experiment) way of  breaking up the Black Holes and liberating what has accumulated inside ?

 

I realize the concept seems ridiculous (I actually hit the submit button too soon and by mistake and so had to continue with the post)  but  what is the answer (can it be said?)

Edited October 27, 2017 by geordief

[beecee]

3 hours ago, geordief said:

Is there anything unexpected that could arise from 2 BHs colliding at speed? Would this just be another form of a Black Hole merger or would this be  a (obviously just a thought experiment) way of  breaking up the Black Holes and liberating what has accumulated inside ?

 

I realize the concept seems ridiculous (I actually hit the submit button too soon and by mistake and so had to continue with the post)  but  what is the answer (can it be said?)

It wouldn't matter what speed two BHs were approaching each other: If their EH's merged, so to would their singularities, and nothing other then gravitational waves would escape, subtracting of course from the overall total mass of the two BHs.

[iNow]

32 minutes ago, beecee said:

nothing other then gravitational waves would escape,

Don’t forget Hawking radiation. 

[beecee]

2 minutes ago, iNow said:

Don’t forget Hawking radiation. 

Agreed, but even with hawking Radiation, nothing is actually crossing from inside the EH to outside.

[geordief]

So even a direct hit  at relativistic speeds would only be expected to produce Hawking radiation?

Would their EHs still  merge completely  in that presumably entirely  ("exponentially entirely" )   improbable scenario?

 

[Strange]

18 minutes ago, geordief said:

So even a direct hit  at relativistic speeds would only be expected to produce Hawking radiation?

Actually, black holes "normally" produce Hawking radiation. And the black hole resulting from such a collision would emit less (because it is inversely proportional to mass).

The collision would produce gravitational waves, at least in the "ring down" phase after the collision (this is where the merged black hole settles down into a sphere again).

Quote

Would their EHs still  merge completely  in that presumably entirely  ("exponentially entirely" )   improbable scenario?

As far as I know, there is no mechanism for black holes to get smaller. For example, if your black holes did not collide head on but skimmed past each other, then they would either merge or they would emerge unchanged (apart from their directions being changed by the gravity of the other). It couldn't "tear off" a mini black hole from one of them.

[geordief]

16 minutes ago, Strange said:

Actually, black holes "normally" produce Hawking radiation. And the black hole resulting from such a collision would emit less (because it is inversely proportional to mass).

The collision would produce gravitational waves, at least in the "ring down" phase after the collision (this is where the merged black hole settles down into a sphere again).

As far as I know, there is no mechanism for black holes to get smaller. For example, if your black holes did not collide head on but skimmed past each other, then they would either merge or they would emerge unchanged (apart from their directions being changed by the gravity of the other). It couldn't "tear off" a mini black hole from one of them.

Does the scenario change at all  (and become more feasible) if we are talking about the smallest possible BHs?(or just smaller ones)

 

  

[Strange]

11 minutes ago, geordief said:

Does the scenario change at all  (and become more feasible) if we are talking about the smallest possible BHs?(or just smaller ones)  

I don't think so. They are less likely to hit each other! And less likely to be attracted to one another. If they were small enough, maybe the Hawking radiation might have a significant effect - pushing them apart?