Theory of relativity
Gravitational waves
Study two masses orbiting their barycenter and producing propagating spacetime ripples — gravitational waves at twice the orbital frequency, . Adjust wave amplitude and time rate to inspect the ripple rings.
Equipment
- Two virtual masses orbiting the barycenter on a 3D mesh
- Wave-amplitude slider (source parameter)
- Time-speed slider and Pause button
- Source-parameter readout; draggable view canvas
Procedure
Identify the wave source
Let the animation run: two masses circling their common center make the quadrupole moment vary, and ripple rings spread in the orbital plane. Drag the canvas for an oblique view — ripples appear only because the accelerating mass distribution is nonspherical.
Verify $f_{GW}=2f_{orb}$
Pause the animation, then lower the time speed: count the ripple rings emitted during exactly one orbit — one wave maximum per half-orbit gives ; for Hz, m.
Vary the amplitude and conclude
Sweep the amplitude slider and read the 'source parameter': the greater the accelerating mass, the deeper the ripples. Note that in reality h ~ , so a detector must measure strains smaller than a proton — the reason LIGO uses Michelson interferometers with 4 km arms.