grow light distance
Light surrounding black holes?
I know very little about cosmology. But I had an idea about black holes, and thought I'd ask you guys about it. So, black holes have such a strong gravity that they can pull light in if it passes close enough. Light that isn't close enough to fall in would be bent (from my understanding). But I was wondering, is it possible that photons traveling at the perfect distance away could actually orbit a black hole (indefinitely, or at least for a while until they fall in or escape)? Obviously, this would not be seen, as the light wouldn't reach us.
One further (if you think that is possible). Over billions of years, light must have accumulated in this "orb" for lack of a better word. Do you think that it is possible that this light could have grown so intense that it would be able to destroy any object that is pulled into it before the intense gravity itself destroy it?
yes, circular light beams around a black hole are possible in principle. One can even calculate their distance from the event horizon, the theoretical "boundary" of the black hole.
It was already in 1916 that Johannes Droste calculated the distance: It is exactly 3 R. Here R is the Schwarzschild radius of a stationary (non rotating) black hole. R = 2Gm/c^2, where G is Newton's gravitational constant, c is the velocity of light and m the mass of the black hole.
But if the black hole is not isolated, i.e. if matter/energy are falling in, its event horizon expands, thus the specific distance for circular light changes, therefore the former circular beams are too close and photons are falling into the black hole. In other words: Black holes with increasing mass have NO stable circular light orbits.
This is true also for rotating black holes. And due to conservation of angular momentum all of nature's black holes should be rotating. Thus light rings are merely theoretical entities, probably not realized within our observable universe.