- #76

- 30,058

- 9,242

We don't have a good complete theory of quantum gravity. We do have a lot of heuristic work that has been ongoing for decades to figure out what we can say about quantum gravity, in the absence of a complete theory, based on the fact that it has to reduce to the familiar gravity behavior we observe in the domain we have observed it in.Do we even know how gravity works at the quantum level??

Right now, I think the key things that are accepted about black holes in a quantum context are:what does Quantum physics say about Black Holes?

The entropy of a black hole is 1/4 of the area of its horizon in Planck units. We don't know exactly what microscopic states underlie this entropy, although there are a number of proposals.

Black holes emit Hawking radiation, and will eventually evaporate if their Hawking radiation temperature is higher than the temperature of their surroundings. (Note that, for black holes we can observe, i.e., stellar mass or larger, their Hawking radiation temperature is orders of magnitude lower than the temperature of their surroundings, which is at least 2.7K, the CMBR temperature, so none of them will be losing mass on net to evaporation any time soon.) We don't know exactly what will be left behind when a black hole evaporates; that's part of the black hole information paradox, which I don't think can be considered solved, although a number of physicists have made claims that it is, since we have no way of verifying any of the proposed models experimentally.