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Author Topic: Rotating black holes (Kerr solution)  (Read 2156 times)


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Rotating black holes (Kerr solution)
« on: July 24, 2017, 03:27:26 PM »
Hello dear team of Universe Sandbox 2,

I have a hint about black holes and there is a difference between rotating and non-rotating black holes. Matter that falls into a non-rotating black hole falls straight in, while in rotating black holes, due to the rotating space, the matter is routed around the black hole like a rotating plate.
In Universe Sandbox 2, when I gave the black hole a rotation, the attraction still looked as if it were a non-rotating black hole.

A graphical representation for a better understanding (see appendix)

The blue ball shows the effect with a rotating black hole. The red ball shows the same effect in a non-rotating black hole.

Furthermore the related papers from the website of the University of Frankfurt in german.



Used for the calculation was the software Einstein tool for Linux systems.

Would it be possible to integrate this effect into Universe Sandbox as this is already a very important aspect for a space simulation. This effect basically affects all objects in the universe that rotate so also planets naturally the effect there is much weaker.

Plasmic Physics

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Re: Rotating black holes (Kerr solution)
« Reply #1 on: August 09, 2017, 04:24:57 AM »
As far as I'm aware, USB does not take account of relativistic physics. Any phenomena so related that does present is just an artificial facade For instance, the gravitational lensing effect of the black hole has nothing to do with the black hole's gravitational field. It is present because it is coded to be present for black holes. You'll notice that it is absent from other hyper-dense objects below the Chandrasekhar limit. Similarly, you'll notice that the speed of light can be violated in USB with no considerations.


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Re: Rotating black holes (Kerr solution)
« Reply #2 on: August 19, 2017, 08:02:41 AM »
Honestly I'd personally love it if this was added. I've known about this little issue but i kept it to myself because most people wouldn't care


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Re: Rotating black holes (Kerr solution)
« Reply #3 on: September 05, 2017, 08:24:16 PM »
I strongly support this idea. It would be very simple to fake without actually taking GR into account, and would add a nice bit of real world simulation for black holes.


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Re: Rotating black holes (Kerr solution)
« Reply #4 on: September 16, 2017, 02:28:32 AM »
It might need to be explained via tutorial for those new to astronomy (I can easily see someone making a bug thread "why doesn't an object fall in a straight line when I drop something into a black hole?" when someone puts a rotation on it but doesn't know about this)  but I support this idea too, rings from other objects would be more like accretion disks...


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Re: Rotating black holes (Kerr solution)
« Reply #5 on: September 18, 2017, 10:30:37 AM »
Jenn, the astrophysicist on Universe Sandbox , is interested in adding some relativity-related effects. She mentions rotating black holes at the end of this blog post, but you may find the whole post interesting: http://universesandbox.com/blog/2016/02/gravitational-waves/


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Re: Rotating black holes (Kerr solution)
« Reply #6 on: December 12, 2017, 05:46:44 PM »
For me it's also very important thing to have in simulation.

Physics are most important in that production.


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Re: Rotating black holes (Kerr solution)
« Reply #7 on: December 13, 2017, 06:58:32 AM »
Keep in mind relativity itself wouldn't be simulated. It would only be post-newtonian corrections to simulate relativity in the current simulation, which would remain an n-body simulation. (Did I get that right?) I'm ok with that, and it might be a very good thing, but I could imagine it leading to unresolvable bug in certain systems, so I just hope we'll be able to turn it off.