This article describes a new theory in physics which has been based on the “divergence-free linear 4-dimensional stress-energy tensor in the Minkowski Space”. The difference between Einstein’s General Relativity and this theory is the different approach. Einstein has deformed (non-linear and non-divergence free) the “4-dimensional Stress-Energy Tensor” by introducing the curved 4-dimensional Riemannian Manifold to explain the interaction between Gravity and Light. The new theory describes the interaction between different fields (Electric, Magnetic and Gravitational) by identical interaction terms, generated by the separate divergence and the separate rotation of the different fields. (equation 24) The conclusion of the new theory is that “divergence-free” and “rotation-free” fields do not interact. When Isaac Newton published his 3 famous equations which became the foundation of Classical Dynamics, he was not aware that he was building the first elemental blocks for the Stress-Energy Tensor in the 4-dimensional Minkowski Space. When James Clerk Maxwell published his 4 famous equations which became the foundation for Classical Electrodynamics, he was not aware that he was building new blocks for the Stress-Energy Tensor in the 4-dimensional Minkowski Space. When Paul Dirac published his famous equation which became the foundation of Relativistic Quantum Physics, he was not aware that he was building further on blocks for the Stress-Energy Tensor in the 4-dimensional Minkowski Space. It was Albert Einstein who was one of the first physicists who discovered the importance of the Stress-Energy Tensor to describe in a mathematical way the interaction between Electromagnetic Radiation and a Gravitational Field. But because there was no match, Einstein deformed the Divergence-Free Linear “Stress-Energy Tensor” by deforming Space and Time. He deformed this Tensor in such a way that he found a very special Mathematics to describe the interaction between Electromagnetic Radiation (Light) and a Gravitational Field. The Theory of General Relativity. And that became a problem. Because Einstein deformed the fundamental building block in physics (the Divergence-Free Linear “Stress-Energy Tensor), nothing fits anymore. Classical Mechanics has no match with Classical Electrodynamics. Classical Electrodynamics has no match with Relativistic Quantum Physics. Relativistic Quantum Physics has no match with General Relativity. It is important to distinguish the “Physical Reality” from a Mathematical Description of it (which is in general an approach). The scalar curvature (or the Ricci scalar) is a measure of the curvature of a Riemannian manifold. Einstein used a curved Riemannian manifold to describe “Gravitational-Electromagnetic Interaction”. But the physics beyond this is the interaction between the different fields. It is possible to describe this in different ways. This new theory demonstrates a more direct approach in the force densities acting between different fields expressed by equation (24). This new theory starts with the Divergence-Free Linear “Stress-Energy Tensor” in the 4-dimensional Minkowski Space. And from this unique Divergence-Free “Stress-Energy Tensor” follows Classical Mechanics, Classical Electrodynamics, Relativistic Quantum Physics and General Relativity. Bringing back the necessary unity in physics. Theories which unify Quantum Physics and General Relativity, like “String Theory”, predict the non-constancy of natural constants. Accurate observations of the NASA Messenger [11] observe in time a value for the gravitational constant “G” which constrains until ( /G to be < 4 × 10-14 per year) . One of the characteristics of the New Theory is the “Constant Value” in time for the Gravitational Constant “G”. A second experiment to test the New Theory is the effect of “Gravitational RedShift” [2]. The “Gravitational RedShift” between an observatory on Earth (Radius = 6 106 [m]) and a Satellite in a Galileo Orbit (Radius = 23222 103 [m]) according “General Relativity”: The “Gravitational RedShift” between an observatory on Earth (Radius = 6 106 [m]) and a Satellite in a Galileo Orbit (Radius = 23222 103 [m]) according “The Proposed Theory”: describes a new theory in physics which has been based on the “divergence-free linear 4-dimensional stress-energy tensor in the Minkowski Space”. The difference between Einstein’s General Relativity and this theory is the different approach. Einstein has deformed (non -linear and non-divergence free) the “4-dimensional Stress-Energy Tensor” by introducing the curved 4 -dimensional Riemannian Manifold to explain the interaction between Gravity and Light. The new theory describes the interaction between different fields (Electric, Magnetic and Gravitational) by identical interaction terms,generated by the separatedivergence and the separaterotation of the different fields. (equation 24) The conclusion of the new theory is that “divergence -free” and “rotation -free” fields do not interact.