Opis danych i programów komputerowych za pomocą liczb jest epistemologicznie użyteczny, ponieważ pozwala określać granice różnego typu obliczeń. Dotyczy to w szczególności obliczeń dyskretnych, opisywalnych za pomocą liczb obliczalnych w sensie Turinga. Matematyczny fakt istnienia liczb rzeczywistych innego typu, tj. nieobliczalnych, wyznacza minimalne ograniczenia technik cyfrowych; z drugiej strony jednak, wskazuje na możliwość teoretycznego opracowania i fizycznej implementacji technik obliczeniowo silniejszych, takich jak obliczenia analogowe-ciągłe. Przedstawione w artykule analizy prowadzą do wniosku, że fizyczne implementacje obliczeń niekonwencjonalnych wymagają występowania w przyrodzie (...) wielkości nieskończonych aktualnie. Za fizycznym istnieniem takich wielkości przemawiają wprawdzie pewne argumenty fizyki teoretycznej, nie są one jednak ostateczne. (shrink)

The evolutionary circuit design is an approach allowing engineers to realize computational devices. The evolved computational devices represent a distinctive class of devices that exhibits a specific combination of properties, not visible and studied in the scope of all computational devices up till now. Devices that belong to this class show the required behavior; however, in general, we do not understand how and why they perform the required computation. The reason is that the evolution can utilize, in addition to the (...) “understandable composition of elementary components”, material-dependent constructions and properties of environment (such as temperature, electromagnetic field etc.) and, furthermore, unknown physical behaviors to establish the required functionality. Therefore, nothing is known about the mapping between an abstract computational model and its physical implementation. The standard notion of computation and implementation developed in computer science as well as in cognitive science has become very problematic with the existence of evolved computational devices. According to the common understanding, the evolved devices cannot be classified as computing mechanisms. (shrink)

Although the formalizations of computability provided in the 1930s have proven to be equivalent, two different accounts of computability may be distinguished regarding computability as an epistemic concept. While computability, according to the epistemic account, should be based on epistemic constraints related to the capacities of human computers, the non-epistemic account considers computability as based on manipulations of symbols that require no human capacities other than the capacity of manipulating symbols according to a set of rules. In this paper, I (...) shall evaluate, both from a logical and physical point of view, whether computability should be regarded as an epistemic concept, i.e., whether epistemic constraints should be added on computability for considering functions as computable. Specifically, I shall argue that the introduction of epistemic constraints have deep implications for the set of computable functions, for the logical and physical Church-Turing thesis—cornerstones of logical and physical computability respectively—might turn out to be false according to which epistemic constraints are accepted. (shrink)

A version of the Church-Turing Thesis states that every effectively realizable physical system can be simulated by Turing Machines (‘Thesis P’). In this formulation the Thesis appears to be an empirical hypothesis, subject to physical falsification. We review the main approaches to computation beyond Turing definability (‘hypercomputation’): supertask, non-well-founded, analog, quantum, and retrocausal computation. The conclusions are that these models reduce to supertasks, i.e. infinite computation, and that even supertasks are no solution for recursive incomputability. This yields that the realization (...) of hypercomputing devices is implausible, and that Thesis P is not essentially different from the standard Church-Turing Thesis. (shrink)

When Ken Malone investigates a case of something causing mental static across the United States, he is teleported to a world that doesn't exist.