HOW DO GRAVITONS ESCAPE FROM A BLACK HOLE?

In Einstein’s theory of General Relativity, the force of gravity around a black hole is described solely by the warping or curvature of ‘space-time’. However, many scientists believe we can also describe gravity, just like the other forces of nature, as the exchange of ‘virtual’ particles – in the same way that particles of light, photons, carry the electromagnetic force. Unfortunately there is, as yet, no such quantum theory of gravity that would describe how it works at this level, although we have some clues as to what it might look like. But crucially, these ‘virtual’ gravitational particles (called ‘gravitons’) aren’t bound by the normal rules of physics. They can pretty much do what they like, including travelling faster than light, as long as they do it before we notice them! Consequently, a black hole’s event horizon presents no barrier to gravitons and hence their communication with the outside Universe.