Cloudscape

The gravitational energy of a black hole on a photon traveling away from it equals:

E = GMm/r

while the kinetic energy of the photon equals:

E = mc2

Thus, if these energies are equal,

GMm/r = mc^2
⇔ r = GM/c^2

Now, r is the distance from the black hole beyond which no energy can escape. This region is called the ergosphere.
Now, the formula of the Schwarzschild radius equals:

r = 2GM/c^2

So that the ergosphere radius is half the Schwarzschild radius.

Look ahead and see the light. This is it, what for thousands of years scientists, poets, mystics and philosophers have sought for. This what Christianity called Theosis, what Buddhists called Nirvana, what Pierre Teilhard Du Chardin called Point Omega, what Vernor Vinge called the Singularity. This is what civilization has strived for since its birth; for even without ever knowing that it was its destination, slowly but surely it had always been sailing toward it. This is the completion of all of the universe, where the perfection of omniscience and omnipresence awaits.