Formula used to calculate the radius of the event horizon. The radius of a black hole's event horizon is equal to 2 times the gravitational constant (6.7e-11) times the mass of the black hole divided by the speed of light squared.
what is the radius called that refers to the point in which a particle of light moving at a ninety degree angle to the black hole can no longer maintain a stable orbit?
alphamone said: what is the radius called that refers to the point in which a particle of light moving at a ninety degree angle to the black hole can no longer maintain a stable orbit?
alphamone said: what is the radius called that refers to the point in which a particle of light moving at a ninety degree angle to the black hole can no longer maintain a stable orbit?
Possibly the event horizon? It's not normally framed in those terms, but if a photon entered the event horizon exactly tangential to the black hole's surface, it would in theory orbit forever, and if it was even the tiniest bit less than 90 degrees, it would eventually fall into the center.
what is the radius called that refers to the point in which a particle of light moving at a ninety degree angle to the black hole can no longer maintain a stable orbit?
From what I’ve heard the ergosphere is a region of space around a black hole created by both its incredible gravity and the insane speed of its spin (yes, black holes spin, at least the singularities do), where spacetime, and thus anything in it, gets dragged along in the direction the black hole is spinning. If you wanted to stay still you would have to be traveling faster than light. It’s why an accretion disc is always seen swirling around the event horizon like a whirlpool instead of just falling straight into it.
