Classroom simulation of gravitational waves from orbiting binaries.

With appropriate caveats, demonstrations using stretched spandex fabric as a stand-in for curved spacetime can convey some of the wonder of general relativity to non-experts. We have extended this idea to build a simple and inexpensive simulation of gravitational waves from orbiting binaries, using a pair of caster wheels attached to a hand drill and illuminated by a strobe light. This setup successfully reproduces the pattern of outgoing spiral ripples that has entered the public imagination through LIGO animations. We use a paperclip plumb bob to measure the amplitude of these two-dimensional spandex waves as a function of orbital frequency, separation distance between the orbiting masses, and distance from the center of mass. We compare our results with those that hold for gravitational waves propagating in three-dimensional space. Our simulation should not be confused with a demonstration of general relativity, but does exhibit some of the same features that gravitational waves share with other forms of radiation in general.