# Will a black hole cause scattering of a gravitational wave?

In my GR textbook, it states that gravitational waves can undergo interference but not scattering.

I am just starting the chapter on linearised gravity concepts (weak field approximation) and my apologies if this is a duplicate.

My questions are:

1. Can gravitational waves undergo refraction, as this effect, (at my naive GR level of understanding anyway) is related to the curvature of spacetime.

2. Is there any intuitive picture of what occurs as a gravitational wave approaches the vicinity of a black hole, but is not scattered.

• Scalar fields, vector fields, and tensor fields can all scatter off of black holes. C.f. Teukolsky equation for scattering of gravitational waves off of Kerr. More generally, look up perturbations of fields on black hole backgrounds. You can also find exercises in many GR books on scattering of scalar fields on Schwarzschild black holes which amounts to solving a separable wave equation using a curved space-time wave operator; for example see project 8.2 in Padmanabhan "Gravitation: Foundations and Frontiers". See also superradiance in Kerr. – FenderLesPaul Jun 21 '15 at 21:44
• @FenderLesPaul thanks for that, I will do the exercises and check I read my textbook correctly. (And read other textbooks). – user81619 Jun 21 '15 at 21:57
• @AcidJazz What textbook is it? – magma Jun 24 '15 at 0:12
• @magma hi it's Cheng,Ta-Pei , Relativity, Graviation and Cosmology, 2010 edition, OUP, p337 "once gravitational waves are emitted,they will not scatter and will propogate undisturbed from inner core of exploding star ". It's fairly light on math, but a good introduction and I have Hartle and Carroll's online notes – user81619 Jun 24 '15 at 7:02