8
$\begingroup$

Does a spinning black hole have a stronger gravity than a non spinning one.After all, a spinning black hole is stretching space-time more, so does that make a difference is gravity?

$\endgroup$

1 Answer 1

6
$\begingroup$

It makes a difference, but not to the strength of the gravity.

Around a spinning black hole (or any other spinning mass) space time is dragged. This effect has been measured around the (spinning) Earth by Gravity Probe B. It would cause a plumb line not to point directly at the centre of the Earth, but slightly forward.

For a rotating black hole, there is a region close to the event horizon, but outside it, in which the gravity (a combination of downwards and sideways accelerations) is so strong that it is not possible to remain stationary, relative to a distant observer, for to do so one would have to travel faster than the speed of light (relative to the local spacetime)

A similar situation exists in a non-rotating black hole, but only behind the event horizon.

So a rotating black hole does not have stronger gravity, but it is different: It is sideways.

$\endgroup$
1
  • $\begingroup$ Angular momentum has energy, which has mass, which should expand the event horizon, everything else being equal, but I know that rotating black holes have a smaller, not larger event horizon. Kind of bends my brain to think about it. $\endgroup$
    – userLTK
    Aug 9, 2023 at 17:46

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .