the virtual particles that are created are the result of a quantum fluctuation ..but the energy of this fluctuation must be zero so 1 particle has positive mass and the other has negative mass ...so that if they annihilate the mass is zero and they go back to not existing but if the one with negative mass is sucked into the black hole ...it takes mass away from the black hole . and the positive particle becomes real instead of virtual basically, speaking, every time when negative particle enters the black hole, black hole loses energy because the negative-energy particle annihilates with the positive energy of the black hole, the black hole shrinks, but it doesn't radiate, while the positive particle that was outside the black hole all that time goes away from the black hole, and we see it as the hawking's radiation. However, what are virtual particles? I need your opinions on that matter!!! I asked for a favor an astrophysicist and he told me the following: Me: Virtual particle-antiparticle pair production is a mathematical technique for describing the state of a field. It does not describe real particles really appearing out of nothing. Hawking himself wrote, in his seminal 1975 paper, "It should be emphasized that these pictures of the mechanism responsible for the thermal emission and area decrease are heuristic only and should not be taken too literally." Virtual particle-antiparticle pair production is a mathematical technique for describing the state of a field. It does not describe real particles really appearing out of nothing. If there were real particle-antiparticle pairs really being created, then what mechanism could possibly force the negative energy particle to always fall into the black hole when the positive energy one can escape? In what sense virtual particles are virtual and distinct from real ones? Honest question -I do not know. Answer: Say that the number of particles in a box is x=20-18. Obviously, this means that there are 2 particles in the box But if you look back into your math, you'll see that there aren't only 2 particles present. There are 38: 20 positive particles and 18 negative particles, which combined to give you your 2 real particles. It would be really inconvenient to formulate the math without referencing the other 36 particles, but that doesn't mean that they have some sort of physical existence. The math is usually just a teeny bit more complicated than integer subtraction, but that's the basic idea. Me: This is something that always fascinates and puzzles me: If the math says something, on what grounds do we say "this is real" and "oh, this is just a math trick"? In the physics I've done, I've seen little of this, so perhaps that's why I am so puzzled. Answer: That's a complicated question that I definitely have no idea how to answer in general. In this specific case, though, we call particles real if there is in principle some way to measure them, because that's generally what people mean when they talk about something being real. Me: My understanding was that "they" have well measurable effects, however. Or am I wrong? For example, after neutrino was predicted but before it was detected, was it considered "real", or not? I thought the former, because it was needed to preserve conservation laws, but again, perhaps I am misguided. Mind you, I know how it comes across, but I am not subtly insisting that they have to be real. I am trying to understand how it works, where is the line. Answer: They have measurable effects only in the sense that they're part of the math and the math predicts measurable things. If something is a real particle, it should be possible in principle to perform a measurement of its position, and you can't do that with virtual particles. This is somewhat tautological, but I'm only using it to explain why we make a distinction between virtual and real particles. So, my question which math models should I take as the grain of salt??? Casimir's effect, virtual particles, something else??? We only have rock-solid proofs that black holes exist (they even detected dying pulses near the black holes, super-gigantic vortexes of infalling matter as well). I'm getting confused here, really confused. Also, just because gravity exists, it doesn't mean gravitons exist. Right? Thanks to all.