Quanta, Wave-Particle Duality and the Uncertainty Principle
A "curved" spacetime is already strange enough, but here we have to deal with a new level of paradoxicity. Energy that is not continuous but comes in "packets", waves that may have particle behavior and particles that may have wave behavior, and to top it all, the Uncertainty Principle.
The work that needs to be done here will depend to a large extend on the work on the previous section on the Electrostatic Field and EM Waves. When we have a clearer picture of EM waves as curvature fluctuations that propagate in spacetime with the speed of light (or maybe the "speed of time"; see Speed of Light and the "Rate of Propagation of Time"), hopefully it will be easier to see how these fluctuations can be quantized as to the energy they carry.