According to Wikipedia:
Hawking radiation reduces the mass and energy of black holes and is
therefore also known as black hole evaporation. Because of this, black
holes that do not gain mass through other means are expected to shrink
and ultimately vanish.
My question is about this shrinking and vanishing part. My (school level at best – I supposed now they teach this stuff better) understanding is that a black hole in order to be a black hole needs to be extremely dense or extremely massive. Does this mean that from some point in time black hole just will cease to be a black hole because it won't be massive enough?
The question suggested as duplicate – An explanation of Hawking Radiation – is actually about the physical nature of the Hawking radiation itself, so, though related, it's still different.
Best Answer
No, once a black hole forms there's no turning back. It can lose mass via Hawking radiation, but (as far as we know) it cannot stop being a black hole until there's nothing left. There's no theoretical lower mass limit for a black hole. There is a possibility that right near the very end of the evaporation process that some quantum effect creates a stable remnant, but we need a proper theory of Quantum Gravity (which unites General Relativity with Quantum theory) to answer questions like that, and we don't yet have such a theory.
As the Wikipedia article explains, Hawking radiation is a very slow process for black holes with the mass of a typical star, and it's very cold, around a billionth of a degree above absolute zero. So it's very difficult to observe, even if you were close to the black hole. The evaporation rate gets faster and the temperature increases as the mass of the black hole gets smaller, but currently the universe is too warm for an isolated stellar black hole to lose mass: it gains far more energy from the Cosmic Microwave Background (CMB) radiation than what it emits as Hawking radiation.