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Hawking radiation tells that antiparticles near a black hole are responsible for its reduction.

But I am having doubt, because when one of the particles goes into the black hole, the other particle goes away from it. So this should increase the size of black hole not decrease it, as it has taken something in. And if by chance the negative particle goes into the black hole, the other particle should also go into it, because of its huge pull, so that the black hole size is conserved.

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  • $\begingroup$ 1) What do you mean by negative particle? 2) What is your question? $\endgroup$
    – Nemo
    Commented Nov 27, 2017 at 20:49
  • $\begingroup$ Two particles which are of opposite nature are generated. $\endgroup$
    – The immortal
    Commented Nov 27, 2017 at 20:50
  • $\begingroup$ One is negative and my questions are everything i have written after doubt $\endgroup$
    – The immortal
    Commented Nov 27, 2017 at 20:53
  • $\begingroup$ I think the idea is that the particle / antiparticle pair happen to be moving in a direction at least slightly different from the direction in which the black hole's event horizon is propagating outward, as there's still no clear evidence that subatomic particles are affected by gravity. $\endgroup$
    – Edouard
    Commented Feb 18, 2020 at 19:17
  • $\begingroup$ It seems Jerry's answer raises more questions: how long does it take the positive-mass particle to reach infinity? According to the answer, it is only at infinity where there is symmetry and energy conservation. Re: negative mass. It is my understanding that anti-particles have opposite charge, not opposite mass. Has negative mass ever been observed? Why should gravity attract negative mass over positive mass? The posted question is a good one and should be considered carefully. My answer is speculative as many answers are bound to be on this topic. If a particle-anti-particle pair are created $\endgroup$
    – garmichaels
    Commented Dec 31, 2021 at 16:02

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The key point here is that the definitions of "zero energy" are different near and far from the black hole. When the virtual particle pair is created near the black hole, it has zero energy, relative to the region near the horizon. Then, a particle with positive mass escapes to infinity. At infinity, however, there is a symmetry that guarantees overall conservation of energy. This means that the black hole had to have lost an amount of energy equal to the energy of the escaped particle. This therefore means that the infalling particle must have had negative mass relative to infinity.

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  • $\begingroup$ +1 for an answer that means my superficial assumptions will have to be reassessed. Also, how come I never see that explanation on the discovery channel :) $\endgroup$
    – user176049
    Commented Nov 27, 2017 at 22:11
  • $\begingroup$ @Countto10: this is still a pretty handwavey argume that I expect someone to be unhappy with, but i did want to make it comprehensible, too. $\endgroup$
    – Zo the Relativist
    Commented Nov 28, 2017 at 15:52
  • $\begingroup$ It seems Jerry's answer raises more questions: how long does it take the positive-mass particle to reach infinity? According to the answer, it is only at infinity where there is symmetry and energy conservation. Re: negative mass. It is my understanding that anti-particles have opposite charge, not opposite mass. Has negative mass ever been observed? Why should gravity attract negative mass over positive mass? The posted question is a good one and should be considered carefully. My answer is speculative as many answers are bound to be on this topic. If a particle-anti-particle pair are created $\endgroup$
    – garmichaels
    Commented Dec 31, 2021 at 16:02
  • $\begingroup$ continued [...] "it is possible the particle could be trapped while the anti-particle escapes. If the particle is trapped, it would have a hard time finding an anti-particle to annihilate with, since there is far more matter than anti-matter, so it seems possible that it could indeed add mass to the black hole." $\endgroup$
    – SuperCiocia
    Commented Jan 1, 2022 at 2:45

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