““We have good reason to believe that space and time begin to merge into quantum mechanical uncertainty at distances this small; they must be treated quantum mechanically from this scale downward. If the diameter of a black hole is well above the Planck length, we are justified in treating the particles that fluctuate about its Schwarzschild radius in terms of quantum mechanics while treating space, time, and gravitational field in the classical terms of general relativity. This is exactly what Hawking did, and his theory makes sense for black holes with diameters well above the Planck length. We will see what that means for the mass, temperature, lifetime, and thermal radiation of a black hole. But we don't know whether or not (and, if at all, how) it shrinks in size below this Planck length. In particular, we don't have any idea whether it will actually disappear in an explosion, leaving behind a flat, undistorted space, or will simply propagate through space as a mini-mini-black hole with a diameter of 10^-33 centimeters.””
