Expert: Ed - 6/23/2010

Question
if we just apply the newtonian mechanics(i.e v=sqrt(GM/R )) for a rotating body with Mass/radius ratio equal to that of a black hole then we get that the velocity of rotation of mass at the edge have velocity equal to that of light.is it means that black hole cant rotate?and if they rotate then velocity of any point at the edge of black hole must be equal to "c".

Answer
Gopal, this is a hard question for me.  Sorry, you will need to ask other people, but I will say what I know.

You are getting at the reason why it is necessary to move beyond Newtonian physics when dealing with black holes.

Study/google topics related to the "stationary limit," and also the ergosphere and its boundaries.  Also the Kerr metric.  That will help give you more useful information.  It sounds like you already have a clear idea of a lot of the issues involved.

I will try to think about this question more.  If you want to get back to me in a few days, maybe I could answer then.  In the meantime, try to do more research on your own, or ask someone else.

Keep Looking Up,
-Ed