Re: Most distant black hole weighed
Posted by Pasti on Mar 22, 2002 at 03:35
(64.10.121.125)Re: Most distant black hole weighed (Paul)
Paul, among other things, there is something called gravitational lensing, which, at least as a principle, could give you info about the size of the mass the black hole.Secondly, there would be anomalous redshifts (what remains after you subtract the Hubble and "peculiar" redshifts)which would again give you info about the mass of the black-hole.
And as a general rule, even in the very elementary theory of black holes, the only quantities available to an observer outside the event horizon are exactly the mass, angular momentum and charge of the black-hole, and as Cougar says, you can measure them,as a general rule,at least from the geometry of the spacetime outside the horizon of the black hole, i.e. from the gravitational effects on other bodies.