The Grand Unified Theory is the unification theory of the four fundamental forces of nature (gravity, electromagnetism, strong nuclear force, and weak nuclear force). It is through the interactions between these four forces of nature that everything in our universe is created, including our DNA and the cells that compose our body. Einstein spent much of the later part of his life trying to unify these forces, but without success. The grand unified theory is also called the theory of everything, because it is supposed to answer many fundamental questions about our universe. The questions such as, why does our universe exist? Why is our universe composed of three-dimensional space and not five or six? What is energy? Why is there conscious life in our universe? What is the function of life in the universal order?