Information

• 1. Introduction

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  Information is something with the power to inform, and a single stone lying in a field can hold a different version of it for every person who walks past. To a geologist, that stone tells one story. To an archaeologist standing in the same spot, it tells another. No information system could ever map every possible meaning that stone might carry, and no single mapping would be the one true reading. This is the strange heart of a word people use a hundred times a day without pausing. We say we want information, store it, lose it, protect it. Yet thinkers cannot agree on whether it is a substance flowing through a pipe, a choice made by a sender, or merely a difference that makes a difference. How did a Latin word for shaping the mind come to describe bits on a hard drive? Why does measuring information mean counting uncertainty rather than counting facts? And how did the year 2002 quietly become the beginning of an age?

• 2. From Form To Stuff

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  The English word information traces back to Middle French enformacion, which once meant a criminal investigation. Its deeper root is the Latin informatio, carrying senses of conception, teaching, and creation. References to information as the formation or molding of the mind, as training and instruction, reach back to the 14th century in English and in other European languages alike. The Oxford English Dictionary records this older meaning. A profound shift arrived between the Middle Ages and Modernity. The concept moved from giving a substantial form to matter toward communicating something to someone. The scholar Peters, writing in 1988, traced how the term drifted from the cosmos into consciousness. At first informed meant shaped by, and later it came to mean received reports from. In empiricist psychology the word seemed to describe the mechanics of sensation, objects in the world informing the senses. For the philosopher Hume especially, sensory experience was a swirl of impressions cut off from any sure link to the real world. Information, Peters concluded, moved from structure to stuff, from form to substance, from intellectual order to sensory impulses. The word that once meant inner ordering came to mean the fragmentary, fluctuating, haphazard stuff of sense.

• 3. The Mathematics Of Uncertainty

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  The bit is the standard unit of information, defined as that which reduces uncertainty by half. Other units such as the nat may be used instead. The whole arithmetic rests on a single insight: the uncertainty of an event is measured by its probability of occurrence, and uncertainty is proportional to the negative logarithm of that probability. More uncertain events therefore require more information to resolve them. One fair coin flip encodes log2 of 2 over 1, which equals 1 bit. Two fair coin flips encode log2 of 4 over 1, which equals 2 bits. Claude Shannon fundamentally established information theory through his work in the 1940s, building on earlier contributions from Harry Nyquist and Ralph Hartley in the 1920s. The field sits at the intersection of probability theory, statistics, computer science, statistical mechanics, and electrical engineering. Its key measure is entropy, which quantifies the uncertainty in the value of a random variable. Identifying the outcome of a fair coin flip, with two equally likely outcomes, provides less information than naming the result of a die roll with six. Other measures matter too, among them mutual information, channel capacity, error exponents, and relative entropy. The theory left fingerprints across the modern world. It proved crucial to the Voyager missions into deep space, to the invention of the compact disc, to the feasibility of mobile phones, and to the development of the Internet.

• 4. Information Without A Mind

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  DNA needs no conscious observer to do its work. The sequence of nucleotides is a pattern that shapes the formation and development of an organism, with no mind required to perceive it. This view treats information as any pattern that influences the formation or transformation of other patterns. The biochemistry of unicellular and multicellular life, with its enzymes and polynucleotides maintaining biological order, predates human consciousness by millions of years. Gregory Bateson captured this reading in a famous phrase, defining information as a difference that makes a difference. Systems theory leans the same way, treating patterns that circulate through feedback as information even when no mind is present. The biophysicist David B. Dusenbery, in his book Sensory Ecology, drew a sharp line between two kinds of input. Causal inputs matter on their own, like food for an organism or energy for a system. Information is different. It matters only because it is associated with causal inputs and can predict their arrival at a later time and perhaps another place. A flower offers the clearest case. The colored light it reflects is far too weak to power photosynthesis, yet the visual system of a bee detects it. The bee's nervous system uses that signal to guide the insect to the flower, where it finds nectar or pollen, the nutritional payoff that is the real causal input.

• 5. Telling Something To Someone

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  Fritz Machlup refused to let information drift away from human minds. In the basic senses he recognized, information always refers to telling something, or to the something that is being told, and it is addressed to human minds and received by human minds. Every other use, including its application to nonhuman organisms or to society as a whole, he judged metaphoric, and in the case of cybernetics, anthropomorphic. He set out this view in the 1983 book The Study of Information: Interdisciplinary Messages, which he assembled with Mansfield. That volume gathered competing positions from computer science, artificial intelligence, library and information science, linguistics, psychology, and physics. Northrup, writing in 1993, located a deeper fault line running through Shannon's theory itself. Two metaphors fight inside it. One pictures information as a quantity, like water in a water pipe. The other pictures it as a choice, made by a provider and forced upon a receiver. The second metaphor implies that information sent is not necessarily equal to information received, because any choice means comparing a list of possible meanings. That smuggles meaning back in. Logically, Northrup argued, Shannon's theory implied that information is a subjective phenomenon, yet Shannon kept speaking of it as an objective substance. The Danish Dictionary of Information Terms offered a tidier formula: information is an answer to a specific question. Whether that answer becomes knowledge depends entirely on the person who receives it.

• 6. Signs And Their Layers

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  Michael Buckland sorted the word into three distinct uses: information as process, information as knowledge, and information as thing. Beynon-Davies explained information instead through signs and signal-sign systems, layered across four branches of semiotics. Pragmatics concerns the purpose of communication, linking signs to the context in which they are used and to the intentions of living agents. It ties language to action. Semantics concerns the meaning a message carries, studying the link between symbols and their referents, and the way signs relate to human behavior. Syntax concerns the formalism that represents a message, studying the logic and grammar of sign systems, the form rather than the content. These layers connect the social world to the physical and technical world. Communication, in this account, lives inside some social situation that sets the context for both intention and form. A sender codes a message in a mutually understood language, then sends it as signals along a communication channel, the layer Beynon-Davies calls empirics. That channel has inherent properties, determining how fast communication can happen and over what distance. Nielsen, writing in 2008, applied this thinking to dictionaries. He introduced the idea of lexicographic information costs, the effort a user must spend first to find data and then to understand it well enough to generate information from it.

• 7. The Digital Age Arrives

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  A 2011 Science article fixed the start of the digital age at the year 2002, the moment digital storage capacity bypassed analogue for the first time. By 2007, that same article estimated, 97 percent of technologically stored information already lived in digital bits. The growth in raw capacity is hard to picture. The world's technological capacity to store information climbed from 2.6 optimally compressed exabytes in 1986 to 295 optimally compressed exabytes in 2007. The earlier figure amounted to less than one 730-megabyte CD-ROM per person, about 539 megabytes each. The later figure was the equivalent of almost 61 CD-ROMs per person. Flows of information ballooned alongside storage. By 2007 the world's one-way broadcast networks delivered the equivalent of 174 newspapers per person per day, while two-way telecommunication networks carried about 6 newspapers per person per day. Around 90 percent of all new information that year was digital, mostly held on hard drives. The numbers since have left exabytes behind for zettabytes. The total data created, captured, copied, and consumed worldwide was forecast to reach 64.2 zettabytes in 2020, and projections pushed global data creation past 180 zettabytes by 2025. A note of caution runs underneath all of it. These figures measure data, not information, because information cannot be directly measured.

• 8. When Information Cannot Be Destroyed

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  Pierre-Simon Laplace imagined a universe so fully predictable that its present was the effect of its past and the cause of its future. The existence of information about a closed system anchors that vision in both classical physics and quantum mechanics, describing an agent's real or theoretical power to predict a system's future from knowledge of its past and present. Determinism is the philosophical theory that causal determination can foresee all future events. Quantum physics complicated the picture by encoding information as a wave function, a mathematical description whose predictions are probabilistic rather than certain. Before Bell's theorem, determinists held on through hidden variable theories, arguing that the information needed to predict the future must exist even if humans cannot reach it. Albert Einstein voiced that conviction with his assertion that God does not play dice. The deepest puzzle waits at the edge of a black hole. When a black hole evaporates completely into Hawking radiation, it leaves nothing but an expanding cloud of homogeneous particles. That seems to make any information about the matter that originally crossed the event horizon irrecoverable, the black hole information paradox. Such loss would violate both classical and quantum rules against destroying information. The same word that began as a Latin term for molding the mind now sits at the center of an argument about whether anything in the universe can ever truly vanish.