Universe Sandbox

Universe Sandbox Legacy => Universe Sandbox Legacy | Discussion => Topic started by: phasma_phasmatis on May 02, 2011, 03:34:09 PM

Title: Dark Matter (and side note: gravitational lensing)
Post by: phasma_phasmatis on May 02, 2011, 03:34:09 PM
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.
Title: Re: Dark Matter (and side note: gravitational lensing)
Post by: atomic7732 on May 02, 2011, 03:37:56 PM
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.
Title: Re: Dark Matter (and side note: gravitational lensing)
Post by: phasma_phasmatis on May 02, 2011, 03:44:30 PM
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.
Title: Re: Dark Matter (and side note: gravitational lensing)
Post by: atomic7732 on May 02, 2011, 04:07:39 PM
I think you're just not being patient.  :P

Seriously, you're probably not going the same amount of simulation time (even though it may seem like it) as on the higher timestep.  :)
Title: Re: Dark Matter (and side note: gravitational lensing)
Post by: phasma_phasmatis on May 02, 2011, 04:58:45 PM
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).