Order of Kilopi
on the first page there was a bit of a discussion that basically boiled down to a geostationary orbit that is also at light speed.
I realise there is a photon sphere around a BH where light can orbit in theory ....but for that to also be "geostationary" to the BH wouldn't the BH have to have a spin that is many magnitudes faster then what would be needed to rip it apart?
Order of Kilopi
Regular objects can have photon spheres too, they just need to be very massive. You have a good point however-- the photon sphere is only 1.5 times the event horizon radius, and so to not be a black hole, the surface velocity of the object would need to be at least 2/3 the speed of light for the photon sphere to be geostationary. That seems pretty physically far fetched. With classical gravity, there's nothing impossible about that-- any speed less than the geostationary speed right at the surface is a possible rotation speed. But I've not included the spin in the gravity, which at 2/3 c is a rather important omission, so you might be right after all.
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