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Digital philosophy is a direction in philosophy and cosmology advocated by certain mathematicians and theoretical physicists, e.g., Gregory Chaitin, Seth Lloyd, Edward Fredkin, Stephen Wolfram, and Konrad Zuse (see his Calculating Space).
Digital philosophy is a modern re-interpretation of Gottfried Leibniz's monist metaphysics, one that replaces Leibniz's monads with aspects of the theory of cellular automata. Since, following Leibniz, the mind can be given a computational treatment, digital philosophy attempts to consider some main issues in the philosophy of mind. The digital approach also try to deal with the non-deterministic quantum theory; digital philosophy assumes that all information must have finite and discrete means of its representation and it assumes that the evolution of a (physical) state is governed by local, deterministic rules. In a digital universe, existence and thought would consist of only computation. (However, not all computation would be thought.) Thus computation is the single substance of a monist metaphysics, while subjectivity arises from computational universality. There are many variants of digital philosophy, but most of them are digital theories that view all of physical realities and cognitive science and so on, in framework of Information theory.
- Rudy Rucker. In his book "Mind Tools" (1987), mathematician/philosopher Rudy Rucker articulated this concept with the following conclusions about the relationship between Math and the universe. Rucker's second conclusion uses the jargon term 'fact-space' ; this is Rucker's model of reality based on the notion that all that exists is the perceptions of various observers. An entity of any kind is a glob in fact-space. The world - the collection of all thoughts and objects - is a pattern spread out through fact-space. The following conclusions describe the digital philosophy that relates the world to fact-space.
- The world can be resolved into digital bits, with each bit made of smaller bits.
- These bits form a fractal pattern in fact-space.
- The pattern behaves like a cellular automaton.
- The pattern is inconceivably large in size and dimensions.
- Although the world started simply, its computation is irreducibly complex.
- Edward Fredkin. In his paper "Finite Nature" (1992), computer pioneer Edward Fredkin stated two fundamental laws of physical information. In terms of unsolved problems in physics these two fundamental laws have two fundamental consequences.
- All information must have a digital means of its representation.
- An informational process transforms the digital representation of the state of the system into its future state.
- If Fredkin's first fundamental law of information is correct then Einstein's theory of general relativity theory is not entirely correct, because the theory does not rely upon digital information.
- If Fredkin's second fundamental law is correct then the Copenhagen interpretation of quantum mechanics is not entirely correct, because quantum randomness lacks a digitally deterministic explanation.
- Stephen Wolfram. In Chapter 9 of  A New Kind of Science, Stephen Wolfram presents an outline of a multiverse automaton.
- Below the Planck scale, there is an informational substrate that allows the build-up of time, space, and energy by means of an updating parameter.
- The updating parameter for the multiverse is analogous to time via a mathematical isomorphism, but the updating parameter involves a decomposition across alternate universes.
- The informational substrate consists of network nodes that can simulate random network models and Feynman path integrals.
- In physical reality, both energy and spacetime are secondary features. The most fundamental feature of reality is signal propagation caused by an updating parameter acting upon network nodes.
- The multiverse automaton has a model consisting of informational substrate, an updating parameter, a few simple rules, and a method for deriving all of quantum field theory and general relativity theory,
- The totally finite nature of the model implies the existence of weird, alternate-universe forces that might, or might not, be too small for empirical detection.
Fredkin's ideas on physics
Fredkin takes a radical approach to explaining the EPR paradox and the double-slit experiment in quantum mechanics. While admitting that quantum mechanics yields accurate predictions, Fredkin sides with Einstein in the Bohr-Einstein debates. In "The Meaning of Relativity", Einstein writes, "One can give good reasons why reality cannot at all be represented by a continuous field. From the quantum phenomena it appears to follow with certainty that a finite system of finite energy can be completely described by a finite set of numbers (quantum numbers). This does not seem to be in accordance with a continuum theory, and must lead to attempts to find a purely algebraic theory for the description of reality. But nobody knows how to find the basis for such a description." Einstein's hope is a purely algebraic theory, but Fredkin attempts to find a purely informational theory for the description of reality. However, physicists find some vagueness, problems with Bell theorem compatibility, and lack of empirical falsifiability in Fredkin's expression of his ideas. In "Digital Philosophy (DP)", Chapter 11, Fredkin raises the question, "Could physics have a strong law of conservation of information?" Fredkin answers his own question, "If so, we have to rethink particle disintegrations, inelastic collisions and Quantum Mechanics to better understand what is happening to the information. The appearance of a single truly random event is absolutely incompatible with a strong law of conservation of information. A great deal of information is obviously associated with the trajectory of every particle and that information must be conserved. This is a big issue in DP yet such issues are seldom considered in conventional physics."
Fredkin's "Five big questions with pretty simple answers"
According to Fredkin, "Digital mechanics predicts that for every continuous symmetry of physics there will be some microscopic process that violates that symmetry." Therefore, according to Fredkin, at the Planck scale, ordinary matter could have spin angular momentum that violates the equivalence principle.There might be weird Fredkin forces that cause a torsion in spacetime. The Einstein-Cartan theory extends general relativity theory to deal with spin-orbit coupling when matter with spin is present. According to conventional wisdom in physics, torsion is nonpropagating, which means that torsion will appear within a massive body and nowhere else. According to Fredkin, torsion could appear outside and around massive bodies, because alternate universes have anomalous inertial effects.
Compatibility between Fredkin's ideas and M-theory
- Fredkin uses many metaphors and analogies in attempting to convey his ideas. Straightforward interpretations of Fredkin's ideas seem to violate Bell's inequalities. However, careful consideration might reveal considerable merit underlying Fredkin's metaphors.
- Let us imagine that our universe consists of the following 5 components:[clarification needed]
- a one-dimensional antimatter clock that measures the flow of information running backward in time;
- a one-dimensional matter clock that measures the flow of information running forward in time;
- a six-dimensional directional-measuring device that measures the flow of information with respect to curvature and torsion of spacetime;
- a three-dimensional volume-measuring device that measures the amount of information with respect to volume;
- an alternate-universe engine that runs the 4 Fredkin measuring-devices with respect to information.
- Let us assume that the 'alternate-universe engine' is basically similar to the model described in Wolfram's "A New Kind of Science", Chapter 9. How might the remainder of the "Digital Mechanics" philosophy described in (1)-(4) possess a meaning in terms of M-theory?
- Matrix string theory formulates M-theory as a random matrix model. M-theory might have a good approximation by a theory that has a gauge group consisting of U(N) for some large N. If such an approximation is valid, then the group U(N) might describe the 4 Fredkin measuring devices. The 6-phase clock described in Fredkin's "Digital Mechanics" might be a counting mechanism for the 6-dimensional directional-measuring device that measures the curvature and torsion of information flow. Note that all 4 of these hypothetical Fredkin measuring devices assume a notion of absolute space, time, and information that would depend upon the 'alternate-universe engine' for any empirical validity.
- Fredkin's concept of the multiverse as a finite automaton with absolute space, time, and information might be isomorphic to a sheaf uniformization axiom. Such an axiom might establish a sheaf structure that supports uniform mapping of Einstein–Hilbert actions and Feynman actions across alternate universes.
- Algorithmic information theory
- Calculating Space
- Cellular automata
- Copenhagen interpretation
- Gregory Chaitin
- Digital physics
- Edward Fredkin
- Fredkin Finite Nature Hypothesis
- Gottfried Wilhelm Leibniz
- Juergen Schmidhuber
- Konrad Zuse
- Loopholes in Bell test experiments
- Mechanism (philosophy)
- Philosophy of physics
- Simulated reality
- Seth Lloyd
- Stephen Wolfram
- Unsolved problems in physics
- Fredkin, Edward, An Introduction to Digital Philosophy, International Journal of Theoretical Physics, no. 2, vol. 42 (2003)
- Rucker, Rudy, Mind Tools - the five levels of mathematical reality - Houghton Mifflin (1987)
-  Fredkin, E.; Finite Nature. Proceedings of the XXVIIth Rencotre de Moriond (1992)
-  Fredkin, Edward; Digital Philosophy
-  Fredkin, E.; "Five big questions with pretty simple answers" IBM Journal of Research and Development Vol. 48, Issue 1 (Jan. 2004)
- Dr. Edward Fredkin's Digital Philosophy site.
- Juergen Schmidhuber's site "Zuse's Thesis: The Universe is a Computer."
- Kelly, Kevin. 2002. God Is the Machine Wired 10.12
- Piccinini, Gualtiero Computation in Physical Systems Section 3.4 of this article discusses the foundations of digital physics/philosophy.
- Longo, Giuseppe O. - Vaccaro, Andrea, Bit Bang. La nascita della filosofia digitale, Apogeo, 2014.