[avg_freeper]

"Gas is being pushed away from the black hole at supersonic speeds over a distance of about a million light-years."

What's the speed of sound in a vacuum?

[snarks_when_bored]

What's the speed of sound in a vacuum?

Sound doesn't propagate in a vacuum. By 'supersonic' in this context, I assume that it means faster than the speed of pressure waves propagating through the gaseous medium surrounding the black hole. Just as objects in our atmosphere can move faster than the sound they generate, so too can gas molecules exceed the speed of the pressure waves generated as they're pushed by the black hole's gravitational and magnetic slingshot effects.

(I'm not a physicist, but I play one on FR.)

[Lurker]

Nice catch.

L