Sunday, February 14, 2016
Gravitational Wave Animations
So I'm still trying to warp my head around the math behind gravitational waves (see what I did there?). They are odd beasts compared to the familiar EM variety; in particular they only have quadrupole and higher radiation characteristics because there is no gravitational analog to a negative-positive dipole.
When they propogate, they cause matter to oscillate in alternate axes. I made a little animation to understand what that might look like:
Something like a gravititational wave... Like looking down the axis of this: https://t.co/IrUFGU0jSz pic.twitter.com/pfN5Lew9x5— r r mutt (@rrmutt) February 15, 2016
What seems to be missing here is a diagonal oscillation rather than purely in the X or Y axis. This turns out to be the quadrupole equivalent of polarization. This leads to the question, can you have circularly polarized gravitational waves by combining the linear X and + polarizations with a phase shift?
Turns out you can, and according to this paper by Smoot (sadly not the same Smoot) they look like a "twisted squashed tube":
According to Smoot, they are a "twisted squashed tube" (pdf: https://t.co/3AGNnvDSNw) pic.twitter.com/iTV7IrYOVx— r r mutt (@rrmutt) February 15, 2016
Here's a hacky isometric projection where the ellipses are plotted at the same size and offset giving a 3D view:
Squashed tube action: circularly polarized gravitational wave pic.twitter.com/7JCfflrSbP— R. R. Mutt (@rrmutt) February 15, 2016