I wish people would just release these types of libraries without any dependencies on Prototype, jQuery, etc. Then people can just write the Prototype or jQuery bridge/bindings/helpers and distribute those as well.
There's no reason for a physics engine to depend on one of these libraries, or even the DOM or Canvas. It's just crunching numbers.
Perhaps it is cleanly separated, I haven't looked.
One of the big advantages of a library like jQuery is that it abstracts away browser incompatibilities. Stuff "just works" in Firefox and Internet Explorer.
I understand that, but as I said, the core purpose of a physics engine is to perform calculations. It shouldn't be tied to the DOM (i.e. where all the browser incompatibilities are) at all.
Many people seem to not understand that the JavaScript language itself is fairly consistent across most browsers; it's the DOM and other browser APIs that aren't.
Release the core as a standalone library, and wrappers for your library of choice.
You can edit draw_world.js to render objects in any way you want. The first change I made was to draw true circles instead of n-gons.