4 ms·

What will happen when black hole will merge with antimatter black hole of same mass?

• Natanael_L 11y ago
  It is no longer antimatter after entering the black hole (edit: once reaching the presumed singularity, but either way you still won't see any difference from the outside). The mass is the same, only the charge is different. They'd merge normally. You might be thinking of negative matter, in which case they'd effectively cancel out, erase each other.
  • danbruc 11y ago
    Nothing strange happens when something falls into a black hole. We could right now be beyond the event horizon of a newly forming black hole. Unless a black hole is particularly small, in which case there will be notable tidal forces near the event horizon, the event horizon of a black hole is a pretty ordinary place hardly distinguishable from flat space. So nothing happens to matter or antimatter when it falls into a black hole.
    • raattgift 11y ago
      You're essentially right on the "no drama" conjecture. However, once through the horizon you switch from the exterior to the interior solution to the EFEs, and find yourself inevitably and very quickly (in proper time) colliding with the singularity or whatever is at the centre of a black hole. You will notice very quickly (seconds to minutes by your wristwatch) that you are inside the event horizon of even a 10^10 M_sun SMBH. That's one reason we can confidently predict we are not inside a black hole with a radius of approximately the Hubble length; we can't use an interior black hole metric to describe our patch of spacetime. If anything, because of the early hot dense universe, we look a bit more like a time-reversal of a interior black hole solution, but even that falls to pieces on inspection. Additionally, unless you believe that the universe is really really different a light year outside the Hubble volume, we also can't use an exterior black hole solution to describe that. (And if you decided for the sake of argument that physics just outside the observable universe is very different, the "outside" metric would still see an expanding surface, which is very not-blackhole-like. The "outside" observers should also be able to infer the spatial flatness of our observable universe; space is decidedly not flat inside a black hole, otherwise we wouldn't have the problem of the infinite density at the singularity.) Unfortunately GR and QFT make different and conflicting predictions about what happens to a positron and electron tossed into a black hole once they reach the region where curvature is on the scale of their Compton length.
      • danbruc 11y ago
        Some of the points you made I was aware of but not precise enough in my comments, of others I wasn't aware and that are great pointers for what I should look into in the future. Thanks a lot for the effort you put into your replies.
      • lisivka 11y ago
        Can you tell us these predictions, please? Is there a way to check them without creating a black hole?
        • raattgift 11y ago
          Not trivially, no. I'll try a not-very-technical answer, since I guess that's what you're looking for. However the main problem is a length/energy correspondence. In quantum mechanics you probe shorter length structures by scattering particles with higher energies. At ultra high energies this produces a shower of daughter particles which carry kinetic energy away, and this process should continue to arbitrarily high energies. More energy in the scattering event produces more daughter particles, which evolve unitarily. In general relativity, when you scatter sufficiently energetic particles, the energy density in the area of the collision is greater than that needed to form a black hole; an event horizon forms around the scattering particles. More energy in the scattering event produces a larger black hole, and we don't know how to preserve unitarity for black holes. Evaporation of small black holes does not produce the same daughter particles as predicted by quantum mechanics. There are other related problems as well, especially in the early hot dense phase of the universe. We do not have the ability now to produce scattering energies of the magnitude necessary to probe the different predictions; we also so far don't have a way to observe natural occurrences of sufficiently high energy interactions at the present time, and might not for many years.