The importance of lTtolecular hierarchy in information processing

In this note I would like to confront some conventional concepts of information processing (selective dissipation) with the facts of molecular biophysics. There are a number of theoretical computers which provide formalizations of the intuitive notion of effective (or algorithmic) information processing. The best known of these is the Turing machine. This is a finite automaton along with a memory space. The memory space consists of units whose states can be changed by the Turing machine-for example, it can write or erase symbols held by these units. The Turing machine can exert some control over which unit it accesses at a given time-for example, it may be able to move the units to the right or left. The way in which the Turing machine acts on its memory space is determined by the transition functions which characterize its finite automaton, for example, the tables which determine the next state and output given the present state and input. The following facts about Turing machines are important. 1. There is a definite procedure for translating the transition tables of the Turing machine into networks of physical elements which give the desired behavior (for example, neural networks). 2 .. It is possible to program a universal Turing machine, that is, a Turing machine which can accept the transition tables of any special Turing machine as input (from its memory space) along with the original input data of this special machine, and transform this input data in the same way as the special machine. Any general purpose computer is universal in this sense. 3. The universal Turing machine can be translated into an actual machine according to the definite procedure in 1. The definite procedure in 1 depends on two features of the components from which the actual machine is built. (a) The components are elementary units with definite transition functions or linkages of these. (b) The transition functions of linkages of elementary units can be derived from the individual transition function and the pattern of linkage, assuming that the inputs to each unit belong to its input set. Each memory unit is also an elementary device-it receives input from the