I just want to know the math of them. For example the Newtonian forces works using the formula F=G*(m1*m2)/d^2
Strange forces was a 30 minute experiment that I hooked up to the 'J' key and then never unhooked. Like a handful of features only accessible on the keyboard it's an experimental feature.
Here's the current (and rather arbitrary) math behind it:
If the distance between the two compared bodies is less than the sum of their radi * 6 then the force between them is multiplied by .1 and made negative (which is why they fly apart when they get too close). F=(-0.1)*G*(m1*m2)/d^2
While I don't expect to provide much control of this in the next version, later versions of Universe Sandbox may allow advanced control over the gravity formula itself.