# Antimatter in a Black Hole **URL:** \ **Category:** Factual Questions\ **Created:** [September 3, 2011, 11:45pm UTC](https://boards.straightdope.com/t/antimatter-in-a-black-hole/595119 "2011-09-03T23:45:40Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![RadicalPi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/radicalpi/32/9806_2.png) [@RadicalPi](https://boards.straightdope.com/u/RadicalPi)\ **Post date:** [September 3, 2011, 11:45pm UTC](https://boards.straightdope.com/t/antimatter-in-a-black-hole/595119/1 "2011-09-03T23:45:40Z")
Let’s say you had a black hole, made of ordinary matter. Let’s call it a thousand solar masses. What would happen if you took another black hole, also about a thousand solar masses, except that this black hole is made out of antimatter, and dumped it into the first black hole? (Let’s ignore the difficulty of doing this for the moment.) I have some guesses, but I don’t know for sure. First, you might get an ordinary black hole of about two thousand solar masses because the weird stuff that happens in black holes makes matter and antimatter lose their ability to annihilate each other. Second, there might be some hind of horrific explosion, but perhaps no one outside the hole would be able to tell. Or maybe, it would be possible to tell since the density at the center might decline for some reason. Which could conceivably ruin the black-holeness of the black hole. So, I don’t know. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [September 3, 2011, 11:47pm UTC](https://boards.straightdope.com/t/antimatter-in-a-black-hole/595119/2 "2011-09-03T23:47:29Z")
I think you would just end up with a bigger hole. The anti matter would forever fall towards the matter but never get there and the matter would do the same - maybe ---
**Author:** ![Snarky\_Kong](https://avatars.discourse-cdn.com/v4/letter/s/a183cd/32.png) [@Snarky\_Kong](https://boards.straightdope.com/u/Snarky_Kong)\ **Post date:** [September 3, 2011, 11:55pm UTC](https://boards.straightdope.com/t/antimatter-in-a-black-hole/595119/3 "2011-09-03T23:55:51Z")
Bigger black hole and an explosion that nobody would know about. I don’t know if you could say that whatever happens is an explosion though. Hmm. In any case, energy has gravity, so I don’t think anything could escape. ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [September 4, 2011, 12:08am UTC](https://boards.straightdope.com/t/antimatter-in-a-black-hole/595119/4 "2011-09-04T00:08:23Z")
The matter/antimatter in a black hole is normally all crushed into (depending on the theory) either a singularity or possibly some kind of exotic matter; in either case, neither normal matter or antimatter. And even if they _are_ still matter and antimatter, nothing escapes a black hole and there’s no way to distinguish which is which from the outside - so you’d never see any matter/antimatter annihilation. As for what happens, as I understand it merging black holes gets you a larger black hole and a really huge but invisible energy release as a substantial amount of its mass converts to gravity waves. ---
**Author:** ![MikeS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MikeS](https://boards.straightdope.com/u/MikeS)\ **Post date:** [September 4, 2011, 12:40am UTC](https://boards.straightdope.com/t/antimatter-in-a-black-hole/595119/5 "2011-09-04T00:40:47Z")
The [no-hair theorem](http://en.wikipedia.org/wiki/No-hair_theorem) tells you that every black hole solution is completely characterized by its mass, angular momentum, and charge. In particular, a black hole that forms via the collapse of an anti-star or what have you is indistinguishable from a black hole formed from the collapse of a star. So the collision of a hole and an “anti-hole” would look exactly the same (to those of us on the outside) as the collision of two normal black holes with the same masses, spins, and charges. The end result in both cases, as noted by **Der Trihs** , is a single larger black hole and some amount of energy/mass radiated away in the form of gravitational waves. ---
**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:** [September 4, 2011, 1:26am UTC](https://boards.straightdope.com/t/antimatter-in-a-black-hole/595119/6 "2011-09-04T01:26:33Z")
> [@](#): > > The no-hair theorem tells you that every black hole solution is completely characterized by its mass, angular momentum, and charge. Nitpick: Charges, plural. Black holes can have both electric and magnetic charge. Granted, nonzero magnetic charges are extremely rare, and it’s possible that black holes are the _only_ things in the Universe that can have magnetic charge. But it’s possible. ---
**Author:** ![MikeS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MikeS](https://boards.straightdope.com/u/MikeS)\ **Post date:** [September 4, 2011, 4:05am UTC](https://boards.straightdope.com/t/antimatter-in-a-black-hole/595119/7 "2011-09-04T04:05:11Z")
> [@Chronos](#): > > Nitpick: Charges, plural. Black holes can have both electric and magnetic charge. Granted, nonzero magnetic charges are extremely rare, and it’s possible that black holes are the _only_ things in the Universe that can have magnetic charge. But it’s possible. I like the idea that a black hole zipped through Stanford in 1982. ---
**Author:** ![RadicalPi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/radicalpi/32/9806_2.png) [@RadicalPi](https://boards.straightdope.com/u/RadicalPi)\ **Post date:** [September 4, 2011, 11:38pm UTC](https://boards.straightdope.com/t/antimatter-in-a-black-hole/595119/8 "2011-09-04T23:38:41Z")
Thanks. I’m somewhat surprised that one of my ideas was pretty much right. ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [September 5, 2011, 1:39am UTC](https://boards.straightdope.com/t/antimatter-in-a-black-hole/595119/9 "2011-09-05T01:39:02Z")
Skittles shoot out.