I think some of the discussions about COMP and simulating people could be better understood if we can first understand a (much) simpler problem: a harmonic oscillator.
The relevance of this is that ultimately there might be no meaning in saying that a string in Platonia or wherever represents anything, without the mapping that gives the semantics for it. If it means something, then we should be able to explicit show how to objectively find this meaning for a simple case of a harmonic oscillator. Let's define a turing machine M with a set of internal states Q, an initial state s, a binary alphabet G={0,1}. The transition function is f: Q X G -> Q X G X {L,R} , i.e., the function determines from the internal state and the symbol at the pointer which symbol to write and which direction (left or right) to move. Write a program in M that calculates the evolution of a harmonic oscillator (HO). The solutions are to be N pairs of position and momentum of a HO, with time step T and d decimal digits. Let this set of pairs be P. The program will eventually halt and the tape will display a string S. The programmer knows (of course) how to read S and find P. The programmer uses for that (unconsciously or not) a mapping A that takes from strings to pairs of real numbers. This mapping depends ultimately on the particular way the programmer chose to write the program and is by no means trivial. Suppose you didn't write this program. Can you look at the output and know that it represents a harmonic oscillator, given that you know all the details of M? This is a problem of reverse engineering which could be feasible in principle for a simple enough program. It would help particularly if M is reversible, since you could from the output work out the program and with enough time and luck, work out what the program is supposed to do. In this way you would be finding the mapping A. But is there anything objective about the string S and the machine M that makes that program represent a harmonic oscillator, or is that interpretation ultimately dependent on the mapping A? Is there some "harmonic oscillatorness" in S? Eric.