[jbri]

Something seems off about the simulation - once you get a big clump, it starts spinning faster and faster until it tears itself apart again.

Ignoring that, it's pretty neat - and runs decently fast as well.

[beloch]

I noticed that angular momentum seems to be an unconserved quantity as well. I would not want to be an astronaut in the universe simulated here!

[raverbashing]

Yeah, this is almost a planetary cloud coming together.

But I suppose the collisions are (too) elastic, also there's the issue with the spinning.

But still you can see several concepts in action, and sometimes you get a big planet with a moon orbiting it.

[drakeandrews]

This is because each "atom" is of a considerable size to the larger clumps and imparts its excess momentum as angular momentum when it joins a clump. "Atoms" that are rotating around a clump in the opposite direction tend to skip off, and thus don't join and slow the rotation. I think.

[jbri]

No, that's not it.

If you restart the simulation a few times, you should eventually get something where everything forms into one clump with low initial angular momentum. If you keep watching from that point, you'll see the clump's rotation accelerate entirely on its own.

I'm not entirely sure on the cause, but it does seem to be a simulation flaw.

[drakeandrews]

You're right. At a guess, as collisions appear to be perfectly elastic particles inside a clump are trying to move and instead of their shifting being dampened, it's causing the whole structure to begin to rotate which causes more in-clump collisions causing... until it spins apart. Sound reasonable?