This is a script for colliding galaxies. The script is ancient (written for Maya 1.0) and images and animations have been floating around for years, but somehow the script itself never got made public. So here, finally, it is. It should be a useful example to illustrate how to work with real-world physical constants, eg the gravitational constant, and how to set up particles into circular orbits.

Some images and animations produced by the script are here:

http://www.realitydiluted.com/mirrors/reality.sgi.com/mwatt_tor/galaxies.html