# How much energy to tear apart a black hole? **URL:** \ **Category:** Factual Questions\ **Created:** [November 14, 2002, 12:44am UTC](https://boards.straightdope.com/t/how-much-energy-to-tear-apart-a-black-hole/136655 "2002-11-14T00:44:24Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [November 15, 2002, 12:04am UTC](https://boards.straightdope.com/t/how-much-energy-to-tear-apart-a-black-hole/136655/21 "2002-11-15T00:04:15Z")
> [@](#): > > i thought anti-matter when it meets matter, it will cancel each other out? no - both are convertet to energy via E=mc^2 where m is mass of matter and antimatter combined the energy can’t escape either so it will most likely condense back into m at the singularity or ring ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [November 15, 2002, 12:35am UTC](https://boards.straightdope.com/t/how-much-energy-to-tear-apart-a-black-hole/136655/22 "2002-11-15T00:35:47Z")
> [@](#): > > the energy can’t escape either so it will most likely condense back into m at the singularity or ring Keep it the hell away from me. I don’t completely understand this, but I have read that there are _extremal_ situations that at first glance would appear to be capable of blowing off the horizon and exposing a naked singularity. The three extremal situations that I know of are extremal angular momentum, spin and charge. For instance (in units G = 1 = c) ((angular momentum J, charge Q): > [@](#): > > if you could get to J/M \> M, the square root would go complex, the horizon would disappear and you suddenly would have a naked singularity. However nature conspires to keep this from happening, and here’s what John Baez says about it: > [@](#): > > This is all interpretable in terms of the thermodynamics of black holes, whose temperature vanishes as you approach these “extremal” situations. > > (The impossibility of reaching extremality is thus analogous to the 3rd law of thermodynamics, and if we ever really understand black hole thermodynamics, it may turn out to be a special case.) ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [November 15, 2002, 7:23pm UTC](https://boards.straightdope.com/t/how-much-energy-to-tear-apart-a-black-hole/136655/23 "2002-11-15T19:23:10Z")
> [@](#): > > \*Originally posted by Sacroiliac \* > \*\*The hole expended enough energy to create two real particles but only got the energy of one them back. \*\* Hmmm…lost me here. First off I thought nothing could escape a black hole so how is it giving energy to create virtual particles? Secondly, I thought virtual particle pairs were just created anyway…no need for an external power source to generate them. I thought the virtual particles in Hawking Radiation were merely what you can find anywhere but these pairs happened to be at the edge of the event horizon of a black hole. I’m not second guessing here…just don’t understand is all. ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [November 15, 2002, 9:09pm UTC](https://boards.straightdope.com/t/how-much-energy-to-tear-apart-a-black-hole/136655/24 "2002-11-15T21:09:25Z")
Virtual particles are not real particles. They exist on borrowed energy and must quickly annihilate and repay this energy. However, the extreme tidal gravitation of a BH can pull them apart with enough force that they gain enough energy to become real long lived particles, and at the same time pay back the energy debt to the nearby negative energy regions of space. So when the hole captures one of these now real particles, it in effect radiates the other one. It has therefore supplied enough energy to create two particles, but only gets the energy of one back. Thus it loses mass. (Warning: Hawking Radiation is actually much more complicated than this, however I only understand it at this level.) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 15, 2002, 9:40pm UTC](https://boards.straightdope.com/t/how-much-energy-to-tear-apart-a-black-hole/136655/25 "2002-11-15T21:40:20Z")
To expand on what **Ring** is saying, you can write down the equations for a black hole with, say Q \> M, but those equations apparently don’t correspond to any real physics. If they did, they would give you a naked singularity, but it’s pretty well accepted that singularities are very modest, and never go out in the nude (besides, a singularity would make a lousy Playboy centerfold). You can add angular momentum, or charge, to a black hole, certainly, but in the process, you’re guaranteed to also add enough mass that the hole stays non-extremal. ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [November 15, 2002, 9:56pm UTC](https://boards.straightdope.com/t/how-much-energy-to-tear-apart-a-black-hole/136655/26 "2002-11-15T21:56:29Z")
**Chronos** you should write a pop science book. You’ve got a real talent for explaining the very complicated in a way the uninitiated (me) can grasp. ---
**Author:** ![erislover](https://avatars.discourse-cdn.com/v4/letter/e/71e660/32.png) [@erislover](https://boards.straightdope.com/u/erislover)\ **Post date:** [November 15, 2002, 11:51pm UTC](https://boards.straightdope.com/t/how-much-energy-to-tear-apart-a-black-hole/136655/27 "2002-11-15T23:51:37Z")
> [@](#): > > So there you go: Just re-create the Universe, and you can split a black hole. I love it! Simple question, and a surprisingly simple answer! 😃 ---
**Author:** ![JS\_Princeton](https://avatars.discourse-cdn.com/v4/letter/j/57b2e6/32.png) [@JS\_Princeton](https://boards.straightdope.com/u/JS_Princeton)\ **Post date:** [November 16, 2002, 6:49pm UTC](https://boards.straightdope.com/t/how-much-energy-to-tear-apart-a-black-hole/136655/28 "2002-11-16T18:49:07Z")
Hawking Radiation is a consequence of Black Hole entropy. (Entropy? you say, Yes, Entropy!) Black hole entropy was actually found to exist as a result of a whole slew of thermodynamic relationships applied to this particular part of space time. In effect, what’s going on is that the observers in accelerating frames see something called Unruh radiation that is a result of a vacuum energy density (creating, it is thought, by particle-anti-particle pairs tunnelling out of nothingness). Since near a black hole’s event horizon you have quite a lot of acceleration (The Equivalence Principle for gravity in a “blind” reference frame says that acceleartion and gravity are indistinguishable), that means you will see a thermal heat bath of radiation. This radiation doesn’t transform away for any part of the universe. However, it’s a ridiculously small effect for the black holes that are large. This is part of the reason Hawking has never recieved a Nobel Prize: Hawking radiation has never been observed. (Though Unruh radiation has been observed, so one might say that it’s nearly a sure thing despite its seemingly impossible threshhold) ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [November 16, 2002, 7:01pm UTC](https://boards.straightdope.com/t/how-much-energy-to-tear-apart-a-black-hole/136655/29 "2002-11-16T19:01:15Z")
> [@](#): > > This radiation doesn’t transform away for any part of the universe. I’m not sure what you’re saying here, but an observer free falling into the hole won’t see any radiation. What looks like a thermodynamic membrane to a hovering observer doesn’t look like anything to an observer in free fall. ---
**Author:** ![NardoPolo](https://avatars.discourse-cdn.com/v4/letter/n/ecae2f/32.png) [@NardoPolo](https://boards.straightdope.com/u/NardoPolo)\ **Post date:** [November 17, 2002, 12:02am UTC](https://boards.straightdope.com/t/how-much-energy-to-tear-apart-a-black-hole/136655/30 "2002-11-17T00:02:15Z")
> [@](#): > > \*Originally posted by Chronos \* > \*\*You can add angular momentum, or charge, to a black hole, certainly, but in the process, you’re guaranteed to also add enough mass that the hole stays non-extremal. \*\* I was wondering about that. Are you saying that if I simply fed a stream of pure electrons into a black hole, it would never reach the point that it would repel the additional electrons from the event horizon by the force of the charge alone? But isn’t gravity a weaker force than electromagnetism? And besides, dreaming of the fireworks involved with having a negatively charged black hole force itself apart at increasing velocity… well, it would neat to watch. From a distance. [Previous page](https://boards.straightdope.com/t/how-much-energy-to-tear-apart-a-black-hole/136655.md?page=1)