Simplicity and Complexity, Regularity and Randomness : exceptional CERN colloquium

The concept of effective complexity, which involves discussing bit strings, utilizing algorithmic information content (AIC), and making a distinction between regularity and randomness, will be explored. Like entropy, the quantities involved all depend crucially on coarse graining and may have other context dependence as well. Besides AIC, which involves the length of programs for a universal computer, it is important to consider also quantities that depend on the execution times for such programs. In that way one can get at pseudo-ramdomness and pseudo-complexity. The presumably simple fundamental laws of physics contribute very little to the AIC of the history of the universe. Instead, almost all of that AIC comes from the results of chance events. Thus it is deeply misleading to refer to the future unified theory of the elementary particles and their interactions as a "theory of everything." Nevertheless, the search for that unified theory, the ultimate regularity in nature, remains a magnificent challenge. Perhaps research on superstrings will point the way toward meeting that challenge.