A feature suggestion.

[DPK]

It is obvious to me that Universe Sandbox has the ability to collide two objects, and add the mass of the smaller object to the smaller one.

What I am suggesting is this, but applied to dust.  Allow dust to collide with more massive bodies and add to their mass, essentially simulating accretion.

The reason for this is simple:  I would love the opportunity to use this program to show the formation of planets around a star, or perhaps the formation of a solar system from nothing but dust and a few more massive bodies.

Is this an outrageous request, or is this something that is actually plausible to implement?

[DPK]

Ok, nevermind.  its already in the spreadsheet.

[vh]

although this isn't possible right now, you can actually do this on a smaller scale. Put some moons/planets in close orbit around the sun ( the closer they are the faster the planets will form) and explode them with a low velocity so that they stay in reasonable orbit. You should have around 1000 lag inducing objects right now. Keep the speed as high as possible without anything flying out and leave the computer running for a loong while (i left mine going for 48 hours )
Eventually the objects will clump together and hopefully form some planets. I left mine going until i had around 3 large ones and ~90 small ones. If you get bored, practing your photon torpedoing skills (y key)

Also, dust must be kept dust because it is just a single point (i think) with no mass. If you added mass, galaxies would be incredibly laggy.  (hey lets rent a supercomputer so we can run the milkyway-andromeda collision with 200x particl multiplier?)

[Sir Fredman]

Well, you *can* actually do this at this moment. Create an empty simulation, add two objects, select them both and you get a nice menu with stuff you can do with those objects, like "balance selected", "zero velocities" etc.

On the bottom of this list is the "auto system" option. If you select this option the system will fill with random moonlets and the game of accretion will begin.

I've started one of these sims yesterday. After 150 years of sim time I have a huge jupiter like central object, nearly a brown dwarf (17.7 jupiter masses) surrounded by a chaotic system of coalescing worldlets. Some of these wordlets can grow quite huge (0,3 jupiter masses or so) but they often fall prey to the central protostar.

Anyway, this type of simulation sure feels like solar system building. One of the feature requests I've posted before is the evolution of objects. The central protostellar mass looked like, well, the moon. So I gave it jupiter.dds and a nice reddish glow. And I'll toggle the 'emit light' button when it reaches 30 jupiter masses

Anyway, the auto system button is mesmerising. Use it at your own risk