[norwaypinesavage]

" it’s spinning one-third the speed of light."

What's spinning at one third the speed of light? The event horizon? The center of the black hole has zero rotational speed.

[Wally_Kalbacken]

It could have rotational speed it doesn’t want to show you.

[MtnClimber]

I think it is the accretion disk which is the disk of material orbiting and falling into the black hole. They must be measuring doppler shift from the light flashes when the smaller black hole passes through the disk twice in its elliptical orbit.

[Recompennation]

What’s spinning at one third the speed of light? The event horizon? The center of the black hole has zero rotational speed.
My question too.
Since when does velocity relate to frequency without amy qualification?
Common core accepted science teaching is really showing.