基于量纲关系推导光速原理的四种方法

he analysis process of the dimensional relationship "energy≡ mass×speed×speed" is presented. The concept of mass body is discussed. The relationship between the maximum value and the uniqueness of physical laws is analyzed. The principle of light speed, which states that the square root of the ratio of the total universal energy to the total universal mass equals to the light speed, is derived from four different methods, i.e., the thought experiment based on the compressing universe, the uniqueness of the physical laws, the concept of inertia and the sum of the infinite series. These four derivation methods have the characteristics of clear logic, simple process and independent of each other. The relationship between the principle of light speed and Noether\'s theorem is introduced..