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LIGO detects most massive black hole merger to date

(www.caltech.edu)
360 points Eduard | 8 comments | 14 Jul 25 20:06 UTC | HN request time: 0.001s | source | bottom
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perdomon ◴[14 Jul 25 20:19 UTC] No.44564794[source]▶
What happens when black holes collide? Does one black hole “consume” the other? Do they become a larger black hole? Does it get more dense or just larger?
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hnuser123456 ◴[14 Jul 25 20:31 UTC] No.44564906[source]▶
They become a larger black hole, mostly conserving mass, minus a few percent to gravitational waves. However, their mass is proportional to their radius, not volume, so it gets LESS dense. If you laid out a bunch of black holes in a line, just barely not touching, and let them merge, suddenly, the whole sphere of space enclosing the line becomes black hole. It also turns out that a black hole with the mass of the universe would have a volume about the size of the universe.
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1. itronitron ◴[14 Jul 25 20:49 UTC] No.44565084[source]▶
>> just barely not touching

Which part of them is barely not touching?

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2. gjm11 ◴[14 Jul 25 20:50 UTC] No.44565104[source]▶
The event horizons.
3. dylan604 ◴[14 Jul 25 21:36 UTC] No.44565636[source]▶
In cosmological terms, what is barely not touching? Is that distance measured in meters, kilometers, AUs, lightyears, parsecs?
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4. hnuser123456 ◴[14 Jul 25 23:06 UTC] No.44566341[source]▶
In terms of creating a row of black holes where the space between each black hole is small relative to the size of the event horizon of each.
5. hnuser123456 ◴[14 Jul 25 23:15 UTC] No.44566386[source]▶
Maybe I should've linked my toy simulator in my initial comment.

https://cybersystems.dev/gtc/gtc.html

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6. marcosdumay ◴[14 Jul 25 23:37 UTC] No.44566497[source]▶
The events horizon.

Or in other words, black holes mergers conserve their total radius, not volume as one would get with normal matter.

7. onestay42 ◴[14 Jul 25 23:47 UTC] No.44566539[source]▶
BTW, the php in /chat2 seems to be broken, if you didn't know already. Great simulation, too.
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8. hnuser123456 ◴[15 Jul 25 00:55 UTC] No.44566872{3}[source]▶
Thanks, I was kinda curious why it wasn't full of spam. it's running on a super neglected rpi, really need to wipe it and spend a month refreshing myself on basic webhosting stuff