from _The End of Science_, by John Horgan John Wheeler and the "It from Bit" ... Beginning in the 1950s, Wheeler had grown increasingly intrigued by the philosophical implications of quantum physics. The most widely accepted interpretation of quantum mechanics was the so-called orthodox interpretation (although "orthodox" seems an odd descriptor for such a radical worldview). Also called the Copenhagen interpretation, because it was set forth by Wheeler's mentor, Bohr, in a series of speeches in Copenhagen in the late 1920s, it held that subatomic entities such as electrons have no real existence; they exist in a probabilistic limbo of many possible superimposed states until forced into a single state by the act of observation. The electrons or photons may act like waves or like particles, depending on how they are experimentally observed. Wheeler was one of the first prominent physicists to propose that reality might not be wholly physical; in some sense, our cosmos might be a participatory phenomenon, requiring the act of observation--and thus consciousness itself. In the 1960s Wheeler helped to popularize the notorius anthropic principle. It holds, essentially, that the universe must be as it is, because, if it were otherwise, we might not be here to observe it. Wheeler also began to draw his colleagues' attention to some intriguing links between physics and information theory, which was invented in 1948 by the mathematician Claude Shannon. Just as physics builds on an elementary, indivisible entity--namely, the quantum--which is defined by the act of observation, so does information theory. Its quantum is the binary unit, or bit, which is a message representing one of two choices: heads or tails, yes or no, zero or one. Wheeler became even more deeply convinced of the importance of information after concocting a thought experiment that exposed the strangeness of the quantum world for all to see. Wheeler's delayed-choice experiment is a variation on the classic (but not classical) two-slit experiment, which demonstrates the schizophrenic nature of quantum phenomena. When electrons are aimed at a barrier containing two slits, the electrons act like waves; they go through both slits at once and form what is called an interference pattern, created by the overlapping of the waves, when they strike a detector on the far side of the barrier. If the physicist closes off one slit at a time, however, the electrons pass through the open slit like simple particles and the interference pattern disappears. In the delayed-choice experiment, the experimenter decides whether to leave both slits open or to close one off _after the electrons have already passed through the barrier_--with the same results. The electrons seem to know in advance how the physicist will choose to observe them. This experiment was carried out in the early 1990s and confirmed Wheeler's prediction. Wheeler accounted for this conundrum with yet another analogy. He likened the job of a physicist to that of someone playing 20 questions in its surprise version. In this variant of the old game, one person leaves the room while the rest of the group--or so the excluded person thinks--selects some person, place, or thing. The single player then reenters the room and tries to guess what the others have in mind by asking a series of questions that can only be answered yes or no. Unbeknownst to the guesser, the group has decided to play a trick. The first person to be queried will think of an object only _after_ the questioner asks the question. Each person will do the same, giving a response that is consistent not only with the immediate question but also with all previous questions. "The word wasn't in the room when I came in even though I thought it was," Wheeler explained. In some ways, the electron, before the physicist chooses to observe it, is neither a wave nor a particle. It is in some sense unreal; it exists in an indeterminate limbo. "Not until you start asking a question, do you get something," Wheeler said. "The situation cannot declare itself until you've asked your question. But the asking of one question precludes the asking of another. So if you ask where my great white hope presently lies--and I always find it interesting to ask people what's your great white hope--I'd say it's in the idea that thw whole show can be reduced to something similar in a broad sense to this game of 20 questions." Wheeler has condensed these ideas into a phrase that resembles a Zen koan: "the it from bit." In one of his free-form essays, Wheeler unpacked the phrase as follows: "... 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, _bits_." ... Wheeler emphasized that science has many mysteries left to explain. "We still live in the childhood of mankind," he said. "All these horizons are beginning to light up in our day: molecular biology, DNA, cosmology. We're just children looking for answers." He served up another aphorism: "As the island of our knowledge grows, so does the shore of our ignorance." Yet he was also convinced that humans would one day find _The Answer_. In search of a quotation that expressed his faith, he jumped up and pulled down a book on information theory and physics to which he had contributed an essay. After flipping it open, he read: "Surely someday, we can believe, we will grasp the central idea of it all as so simple, so beautiful, so compelling that we will all say to each other, 'Oh, how could it have been otherwise! How could we all have been so blind for so long!'" Wheeler looked up from the book; his expression was beatific. "I don't know whether it will be one year or a decade, but I think we can and will understand. That's the central thing I would like to stand for. We can and will understand." Many modern scientists, Wheeler noted, shared his faith that humans would one day find _The Answer_. For example, Kurt Godel, once Wheeler's neighbor in Princeton, believed that _The Answer_ might _already_ have been discovered. "He thought that maybe among the papers of Leibniz, which in his time had not been fully smoked out, we would find the--what was the word--the philosopher's key, the magic way to find truth and to solve any set of puzzlements." Godel felt that this key "would give a person who understood it such power that you could only entrust the knowledge of this philosopher's key to people of high moral character." Yet Wheeler's own mentor, Bohr, apparently doubted whether science or mathematics could achieve such a revelation. Wheeler learned of Bohr's view not from the great man himself, but from his son. After Bohr died, his son told Wheeler that Bohr had felt that the search for the ultimate theory of physics might never reach a satisfying conclusion; as physicists sought to penetrate further into nature, they would face questions of increasing complexity and difficulty that would eventually overwhelm them. "I guess I'm more optimistic than that," Wheeler said. He paused a moment and added, with a rare note of somberness, "But maybe I'm kidding myself." The irony is that Wheeler's own ideas suggest that a final theory will always be a mirage, that the truth is in some sense imagined rather than objectively apprehended. According to the it from bit, we create not only truth, but even reality itself--the "it"--with the questions we ask. Wheeler's view comes dangerously close to relativism, or worse. In the early 1980s, organizers of the annual meeting of the American Association for the Advancement of Science placed Wheeler on a program with three parapsychologists. Wheeler was furious. At the meeting, he made it clear that he did not share the belief of his cospeakers in psychic phenomena. He passed out a pamphlet that declared, in reference to parapsychology, "Where there's smoke, there's smoke." Yet Wheeler himself has suggested that there is nothing _but_ smoke. "I do take 100 percent seriously the idea that the world is a figment of the imagination," he once remarked to the science writer and physicist Jeremy Bernstein. Wheeler is well aware that this view is, from an empirical viewpoint, unsupportable: Where was mind when the universe was born? And what sustained the universe for the billions of years before we came to be? He nonetheless bravely offers us a lovely, chilling paradox: at the heart of everything is a question, not an answer. When we peer down into the deepest recesses of matter or at the farthest edge of the universe, we see, finally, our own puzzled faces looking back at us.