The Schwarzschild radius R for an object of mass M is defined as RBH = 2GM c2 where c is the speed of light and G is the universal gravitational constant. RBH gives the radius of the event horizon of a black hole with mass M. In other words, it gives the radius to which some amount of mass M would need to be compressed in order to form a black hole. The mass of the Sun is about 1.99 1030 kg. What would be the radius of a black hole with this mass? RBH = The mass of the Earth is about 5.98 1024 kg. What would be the radius of a black hole with this mass? RBH = m m RBH = The mass of the Earth is about 5.98 1024 kg. What would be the radius of a black hole with this mass? RBH = Suppose you want to make a black hole that is roughly the size of an atom (take RH = 1.30 10-10 m). What would be the mass M of such a black hole? M = m m kg