How is it that light cannot escape from black holes? Would it be logical to apply escape velocity to this, or does that just explain gravitational pull on earth? Basically, what prevents light from escaping? is there any insight to be had on this?
Every object with mass exerts an attractive force on another mass. So you have to put energy in to overcome this force (this makes running up a hill faster than running down). In the case of a black hole this mass is huge. You can show (ill have a go) that the velocity required to escape completely from a given mass is independant of the mass of the object doing the escaping. 1/2 mv2 = GMm/R (kinetic energy, left equals field energy, right, notice how m cancels) v = sqrt(2gR) (re-arranged g = GM/r) If an object travels at v it can escape with no added forces for Earth this is about 11000m/s. This is why there is so little Helium and Hydrogen found in Earths atmosphere, as these light atoms can reach this speed and escape into space. Anyway back to black holes, the gravitational field around a black hole is very strong, at a certain radius from the centre the pull reaches the point where the escape velocity is faster than the speed of light, so light inside cannot move fast enough to escape.
yeh, alot of confusion sometimes comes from the misconception that gravity does not affect light, or that light has no mass to be affected. THis was proven false as some observations were made of light bending slightly as it passed a planet. It would take a lot of gravity to make light unable to escape, but black holes have a lot of gravity
