Re Earth-sized object orbiting black hole at 5 x Schwarzschild radius: Are you sure that such a small object like the Earth would lose that much energy in a few orbits? All of the simulations that I've seen show _similar-sized_ objects -- e.g., binary black holes -- converging in a few orbits. But the Earth is such a small mass relative an Earth-orbit-sized black hole that I wouldn't think that gravitational radiation would cause the orbit to collapse so quickly. Tidal forces would likely rip the Earth into pieces & possibly schmear it out like Saturn's rings, but I'm skeptical about it collapsing so quickly from gravitational radiation. At 03:37 PM 10/20/2013, Keith F. Lynch wrote:
Henry Baker <hbaker1@pipeline.com> wrote:
According to a recent talk given at UCSB, the largest known black holes have a Schwarzschild radius of the same order of magnitude as the radius of the Earth's orbit -- i.e., 1 AU.
Light would orbit this black hole in a few minutes; I would presume that an Earth-sized object would have to orbit at nearly the speed of light even at 5 AU (Jupiter's distance from the Sun).
That orbit wouldn't be stable. The planet would lose energy by emitting gravitational radiation, and within a few orbits would spiral into the black hole.