Gravitons

In quantum mechanics, a quanta of the gravitational force is labeled h and is called the "graviton." The graviton is formed by breaking up Riemann's metric. This is like hitting a beautiful piece of marble and hitting it with a sledge hammer. 

Objects interact by exchanging this packet of gravity. 

Unfortunately, all of the graviton diagrams with loops come out with infinities. When we sum over all loop diagrams, we find that they diverge. The usual prescriptions of renormalization fail for a quantum theory of gravity. This has prevented the unification of gravity with quantum mechanics for the past half-century. Most efforts to absorb these infinities has been completely in vain. Marble, could not be smashed into pieces.