Relativity and quantum theory, the foundations upon which all of modern physics rests, were developed in the first quarter of the twentieth century. Their accuracy in predicting the results of experiment or observation is astounding; the symmetry principles at their core are among the most beautiful and profound concepts in science. The union of these two models of nature in relativistic quantum field theory led to the development of the standard model of elementary particles and their interactions. The standard model is incomplete, however, it lacks a quantum explanation of the gravitational force.

Gravity is the weakest of the four fundamental forces of nature. Although the effects of gravitational force are easily calculated by the classical laws developed by English physicist and mathematician Sir Isaac Newton in his Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy) or by the modern relativity physics developed by German-American...