photo of John Archibald Wheeler
John Archibald Wheeler

John Archibald Wheeler Postulates "It from Bit"

Fig. 19.1 (the first image in Wheeler's paper). At the end of his caption Wheeler calls this a "Symbol, also, in a broader sense, of the theme that every physical entity, every it, derives fr
Fig. 19.1 (the first image in Wheeler's paper). At the end of his caption Wheeler calls this a "Symbol, also, in a broader sense, of the theme that every physical entity, every it, derives from bits."
In the Proceedings of the Third International Symposium on the Foundations of Quantum Mechanics held in Tokyo, 1989, and published in 1990, American physicist John Archibald Wheeler delivered a paper entitled "Information, Physics, Quantum: The Search for Links." From that I quote first the Abstract and then a few selected paragraphs:

"Abstract: This report reviews what quantum physics and information theory have to tell us about the age-old question, How come existence? No escape is evident from four conclusions: (1) The world cannot be a giant machine, ruled by any preestablished continuum physical law. (2) There is no such thing at the microscopic level as space or time or spacetime continuum. (3) The familiar probability function or functional, and wave equation or functional wave equation, of standard quantum theory provide mere continuum idealizations and by reason of this circumstance conceal the information-theoretic source from which they derive. (4) No element in the description of physics shows itself as closer to primordial than the elementary quantum phenomenon, that is, the elementary device-intermediated act of posing a yes-no physical question and eliciting an answer or, in brief, the elementary act of observer-participancy. Otherwise stated, every physical quantity, every it, derives its ultimate significance from bits, binary yes-or-no indications, a conclusion which we epitomize in the phrase, it from bit."

"19.2 "It from Bit" as Guide in Search for Link Connecting Physics, Quantum and Information.

"In default of a tentative idea or working hypothesis, these questions, no's and clues — yet to be discussed — do not move us ahead. Nor will any abundance of clues assist a detective who is unwilling to theorize how the crime was committed! A wrong theory? The policy of the engine inventor, John Kris, reassures us, "Start her up and see why she don't go!" In this spirit [12-47] I, like other searchers [48-51] attempt formulation after formulation of the central issues, and here present a wider overview, taking for working hypothesis the most effective one that has survived this winnowing: It from bit. Otherwise put, every it — every particle, every field of force, even the spacetime continuum itself — derives its function, its meaning, its very existence entirely — even if in some contexts indirectly — from the apparatus elicited answers to yes or no questions, binary choices [52], bits.

"It from bit symbolizes the idea that every item of the physical world has at bottom — at a very deep bottom, in most instances — an immaterial source and explanation; that what we call reality arises in the last analysis from the posing of yes-no questions and the registering of equipment-evoked responses; in short, that all things physical are information-theoretic in origin and this is a participatory universe. Three examples may illustrate the theme of it from bit. First, the photon. With polarizer over the distant source and analyzer of polarization over the photodetector under watch, we ask the yes or no question, "Did the counter register a click during the specified second?" If yes, we often say, "A photon did it." We know perfectly well that the photon existed neither before the emission nor after the detection. However, we also have to recognize that any talk of the photon "existing" during the intermediate period is only a blown-up version of the raw fact, a count. The yes or no that is recorded constitutes an unsplitable bit of information. A photon, Wootters and Zurek demonstrate [53, 54], cannot be cloned."

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