Can a Black Hole Shadow a Gravitational Wave?

Most recent answer: 02/11/2016

I read the following in a BBC article about the upcoming LIGO announcement about gravitational waves: "Crucially, because they travel straight through matter, nothing can obscure the source of these waves - there are no shadows. And they could offer an unparalleled "view" of objects that don't emit light, like black holes." The comment about "no shadows" got me thinking about what happens when gravitational waves passes through a black hole. Are they not perturbed? No shadow produced passing through the event horizon or the singularity?
- Richard (age 47)
Sydney, NSW, Australia

Good question.   Gravity waves, like electromagnet waves, will be affected by extremely strong gravitational fields like those produced by black holes.     As a practical matter such an effect will be very hard to observe.   You need a very strong continuous source of light, such as a star, in order to see black hole lensing of light.    Detectable gravitational waves are very rare indeed and there are not enough of them around to make a statistical meaningful measurement.


(published on 02/11/2016)