You can create up to 65 objects to float around and interact with each other all at once. Gravitator also let's you view and edit the position, velocity, mass, radius and density of all your "floaters." To make interaction for you easier, everything is done with a simple point and click of the mouse. You will even be able to edit during animation. Don't worry if your animation floats away because your screen acts like a moveable "camera" that will allow you to follow the animation. But the best feature of all is, it's free!