This article is going to show the new solution for unification of electrodynamics and gravitation using new concept of wave particle duality, which is called Combinational Principle. First, it introduces several terms for efficient explanation of such a principle. Then it reviews the concept of wave-particle duality suggested by Rhee. The concept of wave-particle duality newly introduced here is based on indistinguishability between electron “chunk”, and deviation from gravitational shortest path, and new 2 laws of existence. It expands this idea to gravitational field, and it introduces the new concept called combinational principle. This principle uses the new concept of wave-particle duality. It is followed by application of this new principle to fermionic movement which is usually described by Schrodinger equation. Additional effect of gravitation based on combinational principles will be shown. It again followed by another application on hyper macroscopic world of entire universe and black holes, and it naturally arrives at the conclusion on universe expansion.