Coliding Black Holes Simulated

KSMarksPsych
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Topic 191102

Some researchers have simulated via supercomputer what will happen when two black holes colide.

There's a mention of the LIGO project in the article too.

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Kathryn :o)

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Mystic
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Coliding Black Holes Simulated

Mike Hewson
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RE: Some researchers have

Quote:
Some researchers have simulated via supercomputer what will happen when two black holes colide.


I think the important conclusion from that article is that:

Quote:
'that regardless of the different possible orbits and speeds two black holes have when they begin their merger, they end up producing the same signature wave patterns as they near the end of their collision'......'That should make them pretty easy to identify.'


Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter. Blaise Pascal

Chipper Q
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Wow, that's the best I've

Wow, that's the best I've seen yet; the old bowling-ball-on-a-rubber-sheet analogy only goes so far. They did a beautiful job, evident even in a single frame:

Kotulic Bunta
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Yes, they did really nice

Yes, they did really nice job, and the conclusion written by Mike Hewson is important. On the other hand, I doubt that this is very reliable result quantitatively, because merger of two event horizons is not very easily calculable.

I would be interested in how the event horizons look like, not only gravitational waves which can be seen in the public simulation video output.
For example, one interesting work concerning merger of two black holes appeared recently here.

Chipper Q
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RE: Yes, they did really

Message 28227 in response to message 28226

Quote:

Yes, they did really nice job, and the conclusion written by Mike Hewson is important. On the other hand, I doubt that this is very reliable result quantitatively, because merger of two event horizons is not very easily calculable.

I would be interested in how the event horizons look like, not only gravitational waves which can be seen in the public simulation video output.
For example, one interesting work concerning merger of two black holes appeared recently here.


Thanks for that, Kotulic. The analogy between black holes undergoing merger and water droplets undergoing bifurcation looks like a good one, but with relativity in the mix it's still not an easy thing to visualize...

MarkF
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The reported results are

The reported results are great stuff. When they complete the results for unequal masses and/or spinning BHs it will be even more impressive. I would be interested to know how closely they tracked singularities and their evolution. There should be an event when singularities hidden inside each BH connect and merge. For an isolated BH the singularity is a 1D world line and the end point should be a 2D circluarlocus of world lines, what are their geometries between times in the reported case?

Chipper Q
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RE: There should be an

Quote:
There should be an event when singularities hidden inside each BH connect and merge.


Hi, Mark. Is this expected to be observable during ringdown? How can anything inside the event horizon be on differing times? Is there a 'time' it takes for something to travel from horizon to singularity? How can this be?

Kotulic Bunta
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Maybe I am not the very right

Maybe I am not the very right person to answer this, but I am convinced they cannot calculate or even describe any process taking place inside the event horizon(s) - simply because there are no physical laws that should be obeyed (at least we cannot obtain any information about those laws).
So I would suppose that discussion about merger of singularities is completely academical, and the only thing scientists can calculate is the pure merger of event horizons, because this is the last point of universe in the vicinity of the singularities which we are able (with some difficulties) to describe based on our "common" natural laws. The merger of singularities itselves is only something that we know should be happening "behind" or "inside".

Moreover - I don't want to speculate - but maybe there is no singularity - it might be only our incapability of proper mathematical description of the inside region of the BH (or better said - region "outside of our world")...
Mathematics is surprisingly strong tool for description of the world, however, it is only an abstract construction of a man (and I never stopped marveling at its capabilities) and in such extreme (and infinite) cases it might be insufficient and we should "invent" more proper tool.

HansPeter
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RE: Maybe I am not the very

Message 28231 in response to message 28230

Quote:

Maybe I am not the very right person to answer this, but I am convinced they cannot calculate or even describe any process taking place inside the event horizon(s) - simply because there are no physical laws that should be obeyed (at least we cannot obtain any information about those laws).
So I would suppose that discussion about merger of singularities is completely academical, and the only thing scientists can calculate is the pure merger of event horizons, because this is the last point of universe in the vicinity of the singularities which we are able (with some difficulties) to describe based on our "common" natural laws. The merger of singularities itselves is only something that we know should be happening "behind" or "inside".

Moreover - I don't want to speculate - but maybe there is no singularity - it might be only our incapability of proper mathematical description of the inside region of the BH (or better said - region "outside of our world")...
Mathematics is surprisingly strong tool for description of the world, however, it is only an abstract construction of a man (and I never stopped marveling at its capabilities) and in such extreme (and infinite) cases it might be insufficient and we should "invent" more proper tool.

I fully agree with you, a singularity just means that the theory (In this case General Relativity ) brakes down and needs to be replaced with a quantum gravity approach!

MarkF
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ChipperQ: The idea that it

ChipperQ:
The idea that it takes an infinite of time to pass through the Event Horizon is mistaken on two points. First the result comes from a calculation that uses an arbitrarily small test mass i.e. there is no back reaction from the test mass on the BH. Second even that calculation only applies to eternally external observers, for the test mass the time to pass through the EH and all the way to the singularity is finite.

The geometry of the singularities is part of the overall solution of the fields. This is not a casual relationship but rather the singularities, EH and general geometry are all tied together. There are many cases in functional analysis wherein a behavior of the singularities serves as the descriptor of the function.

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