Fundamentals

  Even if we somehow got the data and stored it, the calculations that would be necessary to follow the particles’ motions are even more impractical.

  Nevertheless, practiced balloonists operate their craft with confidence. In some respects, the air behaves in easily predictable ways.

  By introducing radically different concepts—density, pressure, and temperature—we can find simple laws that describe the air’s large-scale behavior. It is those concepts, rather than an atomic description, which answer the questions that balloonists need answered. The atomic description contains much more information, in principle, but most of that information is worse than useless if you’re interested in flying a balloon (worse, because it adds distractions). Consider, for example, the position and velocity of any particular atom. Those properties change rapidly over time, as a result of its motion and collisions with other atoms. The actual trajectory of an atom depends sensitively on the precise starting values, and also on what the other atoms are doing. Thus, information about a particular particle’s position and velocity is wickedly difficult to calculate, and it goes out of date rapidly. In short, it is neither simple nor stable. Density, pressure, and temperature behave much better in those regards. It was a major scientific achievement to discover and quantify those simple, stable properties, which can be used to answer important questions.

  Most of science is a search for simple, stable properties that can answer questions which interest us. We sometimes speak of these as emergent properties. (We ran into this concept before, from a slightly different angle, in chapter 7.) Finding useful emergent properties, and learning to use them skillfully, can be big achievements. The hard sciences have over their history produced many important emergent properties (entropy, chemical bond, stiffness, and so on) and built many useful models based upon them.

  Similar issues arise outside the hard sciences. We’d love to have a more useful understanding of the behavior of people, or of the stock market, for example. The “atomic” versions of those subjects, working up from the behavior of individual neurons or of individual investors—let alone the behavior of the quarks, gluons, electrons, and photons that make them— are hopelessly complex. They are impractical approaches if your goal is to get along in society, or to make money by investing.

  And so we turn instead to different concepts, which you will find in texts on psychology and economics, to answer our large-scale questions. They give us models of people and markets that are complementary to fine-grained, “atomic” models. In psychology and economics, we don’t yet have many models that work as reliably as physicists’ models of gases. The search for emergent properties, and for useful models built up from them, continues.

  There is immense satisfaction in describing the world in terms of its most elementary building blocks. It is tempting to say that this is the ideal description, while other, high-level descriptions are mere approximations—compromises, which reflect weakness in understanding. That attitude, which makes the perfect the enemy of the good, is superficially deep, but deeply superficial.

  In order to answer questions of interest, we often need to change focus. To discover—or invent—new concepts, and new ways of working with them, is an open-ended, creative activity. Computer scientists and software engineers are well aware that in designing useful algorithms, it is important to pay attention to how knowledge is represented. A good representation can make the difference between usable knowledge and knowledge that is there “in principle,” but not really available, because it takes too long and too much trouble to locate and process. It’s like the difference between owning bars of gold and knowing that in principle there are vast stores of gold atoms floating dissolved in the ocean.

  For that reason, complete understanding of the fundamental laws, if we ever achieved it, would be neither “the Theory of Everything” nor “the End of Science.”* We would still need complementary descriptions of reality. There would still be plenty of great questions left unanswered, and plenty of great scientific work left to do.

  There always will be.

  BEYOND SCIENCE: COMPLEMENTARITY AS WISDOM

  Examples from Art

  My musical friend Minna Pöllänen brought up a beautiful example of complementarity in her domain, which I briefly mentioned earlier. In polyphonic music, two very different things occur together—each voice carries a tune, while the ensemble moves through harmonies. We can focus on the melodies or focus on the harmonies. Each is a meaningful way to interact with the music. You can switch between them. But you can’t really do both at once.

  Picasso and the Cubists created visual art that captures complementarity pictorially. By taking up different perspectives on a scene in the same picture, they were liberated to bring out with great freedom aspects they feel are important. Young children do this, too, in their drawings. The bizarre exaggerations and juxtapositions in these artworks emphasize different views that could be considered contradictory. In the physical world, they could not be realized simultaneously. Such up-front complementarity can be charming in a child’s drawings, and genius in a master’s.

  Models of People—Free and Determined

  We construct mental models of people, too, as ways of answering questions about them. For example, if we want to predict how someone will behave in a social situation, we might consider their personality, their emotional state, their life history, the culture they were born into, and so forth. In short, we construct a model of their mind and motives. The concept of will—a mind making choices—is central to this model.

  On the other hand, if we want to predict what will happen to that same person if they are at ground zero of a nuclear explosion, then quite a different model, based on physics, will be appropriate. In that case, mind and will don’t come into it at all.

  Both models—one based on mind and psychology, the other based on matter and physics—are valid. Each addresses a different question successfully. But neither is complete, and neither makes a good substitute for the other. People do make choices, and their bodies are subject to the rules of matter. Those observations are everyday facts. They won’t go away. In the spirit of complementarity, we accept them both. We recognize that neither falsifies the other. Facts can’t falsify other facts. Rather, they reflect different ways of processing reality.

  Do people have choice in what they do, or are they puppets who dance to the tune of mathematical physics? That is a bad question, not unlike asking whether music is harmony or melody.

  Free will is an essential concept in law and morality, while physics has been successful without it. Removing free will from law, or injecting it into physics, would make a mess of those subjects. It is totally unnecessary! Free will and physical determinism are complementary aspects of reality.

  Complementarity, Mind Expansion, and Tolerance

  Let me re-express, in simpler terms, the basic messages of complementarity:

  The questions you want answered mold the concepts you should use.

  Different, even incompatible, ways of analyzing the same thing can each offer valid insights.

  Thus, complementarity is an invitation to consider different perspectives. Unfamiliar questions, unfamiliar facts, or unfamiliar attitudes, in the spirit of complementarity, give us opportunities to try out new points of view and to learn from what they reveal. They foster mind expansion.

  Why not bring this spirit to supposed conflicts between art and science, or philosophy and science, or religion A and religion B, or religion and science?

  It can be illuminating to look at the world in different ways.

  In my own experience, early exposure to Catholicism inspired me to think cosmically and to look for hidden meanings beneath the appearance of things. Those attitudes have proved enduring blessings, even after I abandoned the faith’s strict dogmas. Today, I often go back to Plato, to Saint Augustine, to David Hume, or to “outdated” original
scientific works— Galileo, Newton, Darwin, Maxwell—to converse with great minds, and to practice thinking differently.

  Of course, trying to understand different ways of thinking does not necessarily mean you must agree with them, much less adopt them as your own. In the spirit of complementarity, we should maintain detachment. Ideologies or religions that claim an exclusive right to dictate uniquely “correct” views are contrary to the spirit of complementarity.

  That said, science has a special status. It has earned enormous credibility, both as a body of understanding and as an approach to analyzing physical reality, through its impressive success in many applications. Scientists who define themselves narrowly fail to enrich their minds, but people who avoid science impoverish theirs.

  THE FUTURE OF COMPLEMENTARITY

  Accuracy and Comprehensibility

  The rise of supercomputers and artificial intelligence is changing both the kinds of questions we can ask and the kinds of answers we can seek.

  Bohr himself referred, half-jokingly, to the complementarity between clarity and truth. This goes too far, since there are certainly things, like the basics of arithmetic, that are both clear and true.

  But successful models that require superhuman computations open up an analogous complementarity, which is quite serious. In chess and Go, two games whose mastery was once thought to represent the pinnacle of intelligence, computers are now the best players.

  Each of those games has a large literature, wherein great human players explain the concepts they’ve used to organize their knowledge. The present-day champions—computers—don’t use those concepts. The human concepts are adapted to brains with tremendous powers to use imagery and do parallel processing, but that have relatively weak memories and run at relatively sluggish speeds. A computer can develop entirely different concepts, and also discover the effective human concepts, simply by playing games against itself many, many times and observing what works—in other words, by following the scientific method of learning from experiments.

  In quantum chromodynamics, our theory of the strong interaction, people invented concepts to bridge the gap between the basic equations for quarks and gluons and the more complex objects that finally appear in Nature. Those concepts have helped human minds to get a grip on the problem. To date, however, the strategy that’s worked best—by far—is to hand over the calculations, with minimal instructions, to supercomputers.

  Those examples are distinguished by their clarity (and truth), but the basic phenomenon they exemplify, that thinking machines can discover and use models that are impractical for unassisted human brains, is likely to be widespread.

  In short: Human comprehensibility and accurate understanding are complementary.

  Humility and Self-Respect

  The complementarity between humility and self-respect is, I believe, the central message of our fundamentals. It recurs as a theme in many variations. The vastness of space dwarfs us, but we contain multitudes of neurons, and, of course, vastly more of the atoms that make up neurons. The span of cosmic history far exceeds a human lifetime, but we have time for immense numbers of thoughts. Cosmic energies transcend what a human commands, but we have ample power to sculpt our local environment and to participate actively in life among other humans. The world is complex beyond our ability to grasp, and rich in mysteries, but we know a lot, and are learning more. Humility is in order, but so is self-respect.

  Many decades may pass before autonomous, general-purpose artificial intelligences (AIs) reach human levels. But so powerful are the motivations, and so inexorable is the progress, that barring catastrophic wars, climate change, or plagues, it is likely to take only a century or two. Given the intrinsic advantages in speed of thought, strength of perception, and physical power that engineered devices can offer, the vanguard of intelligence will pass from lightly adorned Homo sapiens to cyborgs and super-minds.

  It is also possible that genetic engineering will produce creatures of superhuman abilities. They will be smarter, stronger, and (I hope and expect) more empathetic than present-day humans.

  To realize that these looming possibilities do, in fact, loom adds, for thinking humans today, a new dimension of humility. Yet self-respect is still in order. In a moving passage from his 1935 novel Odd John, science fiction’s singular genius Olaf Stapledon has his hero, a superhuman (mutant) intelligence, describe Homo sapiens as “the archaeopteryx of the spirit.”* He says this fondly to his friend and biographer, who is a normal human.

  Archaeopteryx was a noble creature and, I suspect, not an unhappy one. Flying—perhaps badly, but better than your fellow creatures, and better than your ancestors—is a heady experience. The glory of archaeopteryx is enhanced, not diminished, by the brilliance of its descendants.

  AFTERWORD:

  THE LONG VOYAGE HOME

  The fundamentals of science are not comfortable. As they teach us, they challenge our habits of thought. Most profoundly, they raise the bar for what we should expect from true understanding. They raise it so high as to make the understanding we have achieved seem eternally inadequate. This is the meaning of John R. Pierce’s ironic observation that “we will never again understand nature as well as Greek philosophers did.”

  The fundamentals of science can undermine faith in received beliefs and conventional wisdom. In particular, they make it difficult to take mythological stories about natural phenomena seriously. It has become all but impossible to believe that Apollo pulls the Sun across the sky with his chariot.

  That undermining process can go much further, beyond merely discrediting absurdities. Scientific understanding bears such abundant and delightful fruit that eating from its Tree of Knowledge can spoil one’s taste for other foods. Nonscientific literature can come to seem stale; nonscientific philosophy silly; nonscientific art pointless; nonscientific traditions hollow—and, of course, nonscientific religion nonsensical. During my early teenage years, in my first heady engagement with modern science, those were my attitudes.

  If a painful narrowing of one’s outlook was the price of accepting the scientific fundamentals, many people would reasonably conclude that the price is too high. Thankfully, the fundamentals of science do not require you to make those corrosive applications of science.

  Science tells us many important things about how things are, but it does not pronounce how things should be, nor forbid us from imagining things that are not. Science contains beautiful ideas, but it does not exhaust beauty. It offers a uniquely fruitful way to understand the physical world, but it is not a complete guide to life.

  On calmer reflection, I began to appreciate those facts. Over time, I’ve come to feel their truth ever more deeply.

  * * *

  • • •

  The child of our introduction, now an adult, may come to understand the fundamental conclusions that science, following its radically conservative method, reaches about the physical world. Then she is prepared to revisit the starting point of her adventure with reality, and to view it afresh, in the light of her knowledge. She can choose, in this sense, to be born again.

  It is not a trouble-free choice. It is disruptive. But the choice is unavoidable, as a matter of integrity. You’ve seen in this book a small sampling of the evidence for the scientific fundamentals. That evidence is overwhelming and indisputable. To deny it is dishonest. To ignore it is foolish.

  And so our heroine comes to reconsider the division of experience into internal and external worlds. The fundamentals of science have taught her a lot about what matter is. She knows that matter is built up from a few kinds of building blocks, whose properties and behavior we understand in detail. And she knows, from direct experience, that scientists and engineers can use such knowledge to make impressive creations. Her iPhone allows her to communicate instantly with friends around the globe, to tap into humanity’s accumulated knowledge at will, and, through pictures and recordings, to snat
ch her sensory world from time’s devouring flow.

  She has learned, too, that the special objects she recognizes as other people, and herself, are made from the same sort of matter as the rest of the world. Many once-mysterious aspects of living things, such as how they derive their energy (metabolism), how they reproduce (heredity), and how they sense their environment (perception), she can now understand from the bottom up. For we now understand, in considerable detail, how molecules—and ultimately, quarks, gluons, electrons, and photons—manage to accomplish those feats. They are complicated things that matter can do, by following the laws of physics. No more, and no less.

  These understandings do not subtract from the glory of life. Rather, they magnify the glory of matter.

  In light of all this, it is radically conservative to adopt what the great biologist Francis Crick has called “the astonishing hypothesis”: that mind, in all its aspects, is “no more than the behavior of a vast assembly of nerve cells and their associated molecules.” Indeed, this amounts to extending Newton’s method of analysis and synthesis to brains. Experimenters in neurobiology have been following that strategy aggressively. And although our understanding of how minds work is still incomplete, so far, in thousands of sensitive experiments, the strategy has never failed. No one has ever stumbled upon a power of mind in biological organisms that is separate from conventional physical events in their bodies and brains. Even in their most delicate experiments, physicists and biologists never had to make allowances for what people nearby were thinking. By now, any failure of Crick’s “astonishing hypothesis” would be astonishing.