Dark Matter (and side note: gravitational lensing)

[phasma_phasmatis]

Does Universe Sandbox 2 simulate it?

If so, how?


Also, how hard would it be for an average computer to simulate gravitational lensing? If it could be implemented without the need for a high-end computer, that would be really cool.

[atomic7732]

Nope... No dark matter. Try placing a galaxy, and let it run. You'll notice it'll spiral way too much.

Microlensing: It's just bending light... It'd have to calculate gravity on light... That might take a good computer.

[phasma_phasmatis]

Aw. Maybe in a couple years when computers are more powerful it would be possible.

Anyway, when I run a milky way sim, and the time step is relatively small, the spirals seem stable.

It's only when the time step gets inaccurate that the spiral starting to fling out.

[atomic7732]

I think you're just not being patient. 

Seriously, you're probably not going the same amount of simulation time (even though it may seem like it) as on the higher timestep. 

[phasma_phasmatis]

I just tested it. From what i'm seeing, the spirals are stable.

Whenever I increase the time step, the spirals do change shape, once i stop changing the time step, they stop changing shape and remain stable.

Whats happening is that when the time step increases, the calculations for the dust particles with a smaller SMA becomes too inaccurate and they fly off. The higher the time step, the bigger the SMA of instability.

I think the dust particles do not have real world velocity and the sim is setting the particles to auto-orbit (at a fictional velocity).