ABSTRACT
This chapter considers our body as a kind of operator which transforms one set of input to another set of output. The difference between such real life operators and mathematical operators is perhaps that the latter do not “consume” input and the output is also not inconsistent. The body can be considered as a set of operators where the elements are ears, eyes, and nose. Input of each of these operators belongs to some space, and the output may be considered as the positive and negative feelings whose values are as continuous as real numbers. Operators are used to express mathematical problems generally in the form of equations or functions to be solved or optimized. Useful mathematical theories of operators are developed for the sets which have the structure of vector spaces. The term “spectrum” is motivated by quantum mechanics where spectral energy is characterized as eigenvalue.
