ABSTRACT
The statement of this problem was reviewed in chapter 4. We have a classical theory of gravity, general relativity, that was constructed by Einstein a century ago. This correctly describes gravity on large scales where we do not expect quantum mechanics to be important. While this is all well and good, we know that the world is in truth described by quantum mechanics. We do have working examples of quantum theories that describe the strong, weak and electromagnetic forces, and we expect that this should extend to gravity. What is needed is a quantum theory of the gravitational force, which will reduce to general relativity at large distances but at short distances will provide a truly quantum theory.
