In this context, “negative mass” is a mathematical convenience rather than an actual particle having negative mass.
Think of it more like “energy required to pull apart a matter-antimatter pair”. In the vacuum of space, the energy that created the pair gets returned when they annihilate. But when near a blackhole, it had to “burn” some of its energy to interrupt that process. Energy is mass, so the blackhole gets less massive.
Mind you this is a very basic explanation of it. It’s just another quantum whackyness of our universe.
In this context, “negative mass” is a mathematical convenience rather than an actual particle having negative mass.
Think of it more like “energy required to pull apart a matter-antimatter pair”. In the vacuum of space, the energy that created the pair gets returned when they annihilate. But when near a blackhole, it had to “burn” some of its energy to interrupt that process. Energy is mass, so the blackhole gets less massive.
Mind you this is a very basic explanation of it. It’s just another quantum whackyness of our universe.