# Structural and Symbolic Information in the Context of the General Theory of Information
## 6 Relations and Interactions between Symbolic Information and Structural Information  
There are intrinsic relations and operational interaction between symbolic information and structural information. For instance, exploring the structure of the surrounding world by trial and error using mutation and selection in the course of Darwinian evolution, biological species accumulate in their gene pools symbolic information as successful recipes for their survival; \"The theory of life is a theory for the generation of information\" [16]. At the same time, symbolic information in genes is also structural information as it predetermines the inner structure of the evolving organism. Similarly, scientists observe and investigate the structures encountered in nature and in laboratory experiments. Structural information is extracted and converted into symbolic information, in the form of articles and books, data tables, or oral lectures given to students and colleagues. Although we do not possess a suitable general theory for the formulation of information conservation laws valid for the research process, we feel intuitively that the amount of symbolic information produced cannot exceed the amount of structural information that is embodied by the research target. Formal approaches to such a putative conservation of information are often discussed as \"no-free-lunch theorems\" [60]. If there were a perpetuum mobile of the fourth kind that does nothing but generate useful symbolic information without input of structural information, a great deal of money could be saved which is currently spent on satellites, particle accelerators, or geological drilling. The invention of such a machine of universal knowledge is very unlikely even though its existence is not forbidden by any natural law we know of. Similar to the overwhelming empirical evidence for the validity of the Second Law, some people believe in the physical impossibility of a perpetuum mobile of the fourth kind based the experience that systematic prophecy and fortune telling often failed in the past. Winners of lotteries are not counted here as prophets. Humans tend to believe in divine beings, oracles, or superstition equipped with the gift of prophecy, but this wishful thinking is not supported by scientific observational evidence. Contemporary science was not able to observe information transfer against the arrow of time. However, science is always in the process of development and growth. As a result, it has been demonstrated that utilization of oracles can be very useful for people [59; 61; 62]. The assumed conservation of information during the transfer of structural information to symbolic information is also valid for the reverse process. Symbolic information has the purpose of being transformed back to structural information, in the form of actions taken based on the information, or of structures generated by symbolic instructions. The phenotype of an organism is an incarnation of its symbolic genetic information. Similarly, a technical product is an incarnation of symbolic recipes or construction plans. The final product is a structural representation of the former symbolic information--new phenotypic traits do not appear unless the genetic code includes the instructions for their ontogenetic development. Conservation of information during the conversion processes between structural and symbolic information, as described before, is rather different from conservation of information during transmission processes from structure to structure, and from one symbolic information processor to another. Structural information is transferred according to physical interaction laws. A quantum state, say, described by a wave function, transfers its information to the subsequent quantum state, as described by the time evolution of the Schrodinger equation. Physical interaction is materialized by the transfer of matter, energy, and entropy, and is governed by their respective conservation laws.