# Charge in a black hole.

1. Jul 24, 2011

### cragar

What if I shoot a bunch of electrons into a black hole, could I make the coulomb repulsion over come the gravity and maybe push the black hole apart?

2. Jul 24, 2011

### espen180

Check out the Reissner-NordstrÃ¶m metric, which describes a spacetime containing a charged, nonspinning black hole. You will see that there is an upper bound on the charge the hole can carry before it becomes a naked singularity. However, the constituent matter/energy will not escape.

http://en.wikipedia.org/wiki/Reissner-NordstrÃ¶m_black_hole

3. Jul 24, 2011

### cragar

thanks, Ill read more about it. Why do people say that gravity is weak if in certain cases gravity can over power the other fundamental forces? Or does there come a time when I wouldn't be able to shoot more electrons into the BH, Like the E field of the BH would push the electrons away?

4. Jul 24, 2011

### atyy

5. Jul 24, 2011

### pervect

Staff Emeritus
Naked singularities exist as a solution to the charged black hole equations,but you can't turn a non-naked black hole into a naked singularity by feeding it charge. In order to get the charge into the black hole, you'll have to give it enough mass that it won't become a naked singularity.

This is mentioned in MTW, for instance, I'd have to look up the exact reference. It should be mentioned in most other textbooks, too.