I Black Holes Colliding Exactly Head On

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Where would the energy go?
Hi,

So when black holes circle each other and eventually collide to form one larger black hole [I believe] that the gravitational potential energy is turned into ripples in spacetime. But that makes me wonder, what if two black holes collided exactly head on? Surely there is a massive amount of gravitational potential energy that.....where would it go?

Thanks,
p
 
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It isn't as simple as "gravitational potential energy", since you can't really define that in the kind of spacetime you get with two black holes. However, energy is carried away as gravitational radiation, yes. If it doesn't get carried away somehow it simply contributes to the mass or spin of the final black hole. So two holes colliding head on make a different (probably larger) black hole than an identical pair that spiral in.
 
Moderator's note: Thread moved to the relativity forum.
 

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