Stellar-Mass Black Hole Simulated by Supercomputer

[flightmaster]

Pretty cool!

[Stochasty]

Cool movie, but BH accretion disks aren't really the state of the art in numerical relativity.

Why simulate dust falling into a black hole when you can simulate two black holes falling into each other, or neutron stars falling into black holes, or white dwarves colliding and possibly forming black holes?

Harder to find good movies of these, though, since most of the visualizations are created with research (rather than publicity) purposes in mind.

[kahlzun]

aren't black holes pretty easy to simulate: single-point gravity attractor?

[Themohawkninja]

Cool movie, but BH accretion disks aren't really the state of the art in numerical relativity.

What do you mean by numerical relativity?

Harder to find good movies of these, though, since most of the visualizations are created with research (rather than publicity) purposes in mind.

Isn't it better to visualize actual research than PR movies?

[Themohawkninja]

aren't black holes pretty easy to simulate: single-point gravity attractor?

I wish it were that easy, I'd do it on my quad-core i7 here at my house.

General and special relativity, along with spacetime get greatly warped and basically broken by the intense gravity, and when you combine that with trying to simulate plasma physics going light speed at millions (of not higher orders of magnitude) of degrees, the math gets intense.

[K^2]

aren't black holes pretty easy to simulate: single-point gravity attractor?

Black hole doesn't work as a gravitational attractor. It's a far more complicated object. Still, simulating small amount of matter traveling near a single black hole is relatively easy. You use the known solution for the metric and then it's only slightly more complicated than doing ordinary orbital mechanics. It's still a bit more complicated because you are doing things in 4D and there are some extra issues with numerical integration. But it's straight forward enough.

On the other hand, if you have multiple black holes or something really heavy falling into one, the problem becomes very, very complex. Not only do you have to solve for motion of everything, but you have to solve for metric that is caused by all of the stuff moving around. Equations for metric are non-linear tensor equations, so solving them precisely is tricky and takes up a lot of memory and computing power.

[Stochasty]

What do you mean by numerical relativity?

Errr... I mean numerical relativity? Numerical simulation/evolution of the Einstein field equations for gravity (with hydrodynamical simulation thrown in for good measure for those classes of problems which involve matter).

I don't understand what possible other meaning the term numerical relativity could have, so I admit to being confused by your confusion.

[Themohawkninja]

Errr... I mean numerical relativity? Numerical simulation/evolution of the Einstein field equations for gravity (with hydrodynamical simulation thrown in for good measure for those classes of problems which involve matter).

I don't understand what possible other meaning the term numerical relativity could have, so I admit to being confused by your confusion.

I just never heard the term. I know what general/special relativity is, but not numerical.

[Stochasty]

I just never heard the term. I know what general/special relativity is, but not numerical.

Ah. I see. I guess I should have used the term "numerical general relativity" since that's what's actually being simulated, but everyone in the field just uses "numerical relativity."