Pursuit Of Unity And Explore The Complexity: The Scientific Understanding Of The Two Dimensions

The pursuit of unity has been the basic object of natural science. This is particularly prominent in physics. In the 20th century, especially Since Einstein advanced the Unified Theory, this pursuit becomes even fiercer, important cases are Yang --Mills Gauge Field Theory, Weinberg, Salam's Weak Unified Theory, Green and others'Superstring Theory. The 20th century is also seen as the turning point of science, which is manifested mainly in the rise of a series of system science. In the second half of the 20th century ,two scientific mainstreams are formed gradually in the scientific community:Physics and System Science. The pursuit of unity in physics and the exploration of complexity in system science evolved rapidly into two scientific thoughts.It is worth mentioning that while the two major trends were flourishing, they mutually exclusive at the same time. This can be seen from the following two aspects: First, the scientific concepts of the two thoughts are different; second, their description of the scientific world is different. The writer puts forward that the root cause of this difference is: Nature is a unified organic whole but also a complex evolutionary process, unity and complexity are the basic properties of nature. Meanwhile, the two thoughts are not the same in the perspective of understanding nature; one is against the direction of the evolution of nature, the other follows along the direction of natural evolution.In fact, in the early 20th century, Poincare pointed out that the development of science had two trends: one is the unity and simplicity, the other is change and complexity. That is to say, on one hand, science as a tool for understanding nature, its goal is simple and united; on the other hand, natural evolution is becoming more and more complex, the exploration of complexity is an inevitable necessity of scientific development. We need to observe these two roads of science in rational eyes. In the history of science, the pursuit of unity is the main approach of scientific progress; however, the absolute and one-side pursuit of utility will lead to the end. Exploring the complexity is a new perspective to probe into the essence of nature, but complexity science is not yet mature, and to establish a sound"unified theory of complex system"is very difficult or perhaps impossible.This paper reviews the occurrence of the two major scientific thoughts, the history of their development, discusses the drawbacks and defects of their isolated development, and then the author analyzes the dialectical relationship between"unity"and"complexity", and concludes to the view that the two are both exploring the nature of the physical world, they provide us two different ways of recognition, and also show us two different scientific approaches, they exclude each other on one hand and complement on the other hand.