Turbulence is necessary to explain why gas in accretion disks is able to move inward toward the center.

“so what people suspected and uh with good reason is the reason that the discs work the way they do is it's not just friction but the gas itself is turbulent so it's a little bit like the what you see in your sink when you turn on the faucet there's a lot of or a river there's a lot of churning and b”