statistics there is something very comforting about newtonian mechanics you push down on one end of leverand the other end goes up you throw ball up in the airit travels parabolic pathand comes down !in shorteverything happens for reason the physical world is completely predictable place--all future states of physical system can be derived from knowledge about its current state for centuriesthis was the prevailing scientific wisdomthen along came quantum mechanics and the copenhagen doctrine the doctrine' proponentsled by bohr and heisenbergargued that at its most fundamental level the behavior of the physical world cannot be predicted one can make probabilistic statements of the form " is highly likely to occur,but not statements of the form " is certain to occur other distinguished physicistsmost notably einstein and schrodingervehemently disagreed this debate roiled the worlds of physicsphilosophyand even religion the heart of the debate was the validity of causal nondeterminismi the belief that not every event is caused by previous events einstein and schrodinger found this view philosophically unacceptableas exemplified by einstein' oftenrepeated comment"god does not play dice what they could accept was predictive nondeterminismi the concept that our inability to make accurate measurements about the physical world makes it impossible to make precise predictions about future states this distinction was nicely summed up by einsteinwho said"the essentially statistical character of contemporary theory is solely to be ascribed to the fact that this theory operates with an incomplete description of physical systems the question of causal nondeterminism is still unsettled howeverwhether the reason we cannot predict events is because they are truly unpredictable or is because we don' have enough information to predict them is of no practical importance while the bohr/einstein debate was about how to understand the lowest levels of the physical worldthe same issues arise at the macroscopic level perhaps the outcomes of horse racesspins of roulette wheelsand stock market investments are causally deterministic howeverthere is ample evidence that it is perilous to treat them as predictably deterministic this book is about using computation to solve problems thus farwe have focused our attention on problems that can be solved by predictably deterministic computation such computations are highly usefulbut clearly not sufficient to tackle some kinds of problems many aspects of the world in of course this doesn' stop people from believing that they areand losing lot of money based on that belief