# Tag Info

3

As John Rennie already put it, Hawking radiation is an semi-classical effect derived by treating the spacetime classically, including the source terms if any, and quantizing fields in the curved background. In addition general relativity has problems with distributional sources, so it is not clear how to treat elementary particles in this case. So one cannot ...

2

This is really a comment, but it got too long for the comment box. The problem is that the Hawking calculation is semi-classical. That is, it assumes the spacetime curvature is given by the (classical) Einstein equation. Once the radius of the event horizon decreases into the quantum regime the approximations Hawking used are no longer valid. You would need ...

1

As I mentioned in a comment to John Rennie's answer, a Schwarschild black hole has only one non-zero curvature invariant -- a quantity that can be defined in a coordinate-independent way. The usual form of this invariant is $$\Psi_2 = -\frac{r_s}{2r^3}$$ where $r_s$ is the radius of the black hole, $r_s = 2Gm/c^2$. (The notation $\Psi_2$ is standard). This ...

Top 50 recent answers are included