宇宙、地球の構造的階層--複雑系科学としての地質学 その2--

Abstract

The philosophical concept of the "system formation levels" in nature and world has been discussed and widely accepted in physics, biology, and some social sciences including economics in Japan. Each level is characterized by specific features formed by the constituent systems with an independent or self-reliable nature. The each constituent system is also formed by systems with such nature of lower levels. Rather recently, it was stressed that the special features of these levels are caused by different specific roles of four essential forces namely gravity, weak interaction, strong interaction, and electromagnetic force. It was pointed out also that "three structural level series discriminated by three size-density relations" are formed by the different roles of the forces. Thus the term "system formation level" can be used with two meanings. A wide, rather indistinct meaning and a narrow essential definition. On the whole, the "system level" concept is significant in geology as well. Our world, namely the universe, came into creation 13.7 billion years ago by the Big Bang. After that, its constituent materials and its complexity developed forming different "levels" of material systems in chronological order over time. That is to say, separation of the four forces occurred first. These were followed by the birth of various particles and bodies of different levels step by step. They are quark, elementary particle, atom, molecule or crystal body, the common materials on the earth, organic bodies and the biosphere. It must be noted that this process of building up from the lowest level (quark) to higher levels is the same in fact as the process of the birth of the universe, galactic systems and star systems, planet systems including the earth, and the common materials on the earth. That is to say from the highest level (the universe) to the lower levels. Through this long process of 13.7 billion years and after the geohistory of 4.5 billion years, effects and consequences of innumerable occurrences have piled up on the earth forming very complex structures of various sizes and levels. In fact, the earth possesses every characteristics of a real complex system now. It is to be noted, however, that the system composition level structure is not very distinct as far as the inorganic world above crystal body level is concerned. On the other hand, the biological world (biosphere) on the earth is characterized by the development of distinct level structure which consists of typical complex systems. On the whole, the earth (Gaia) is a complex system. Geology is a science which studies four dimensional material and phenomena inside this complex system.