> sufficiently close to a black hole it is impossible for particles to safely follow circular orbits. Health and safety gone mad! Weirdly, it's hard to actual

> sufficiently close to a black hole it is impossible for particles to safely follow circular orbits. Health and safety gone mad! Weirdly, it's hard to actually find information about this using the phrase "plunging region", as if you search for it everyone is currently regurgitating the strange Oxford press release wording of "safely". Which is an ironic turn of phrase because the result of the plunge is falling into a black hole. Though I think they probably mean that the circular orbit itself would be safe, not that the particle is falling in deliberately to avoid orbiting in some unsafe manner within a circular orbit! But the Wikipedia article is actually pretty clear: https://en.wikipedia.org/wiki/Innermost_stable_circular_orbit https://en.wikipedia.org/wiki/Innermost_stable_circular_orbi.... So closer than 3 Schwarzschild radii, you can in theory have an circular orbit instantaneously, at a speed lower than light (until the photon sphere at 1.5Rs, where you have to orbit at c). If it was Newtonian rules, you could just orbit here. But because spacetime is warped inwards, anything actually in such an orbit will tip off the circular orbit and into a lower orbit, where it tips inwards and so on, into an inward spiral. It seems a bit like one of those coin spiral games/charity boxes where the coin spirals down a curved cone-like funnel into the central hole. Even a coin injected tangentially eventually falls in, because the continously curved inward slope of the surface always makes the coin turn inwards and resists a stable orbit (even if it had no friction or air resistance).