A couple of years ago, in one of the scientific journals,1 I came across a concept that was then new to me: “emergent property.” I forget the original context of the article, but the author used the example of a tabletop to illustrate the idea. From our perspective at the human scale, the top is a flat plane, but at the atomic level, the flat surface disappears into a lumpy swarm of molecules. Aficionados of fractal imagery will understand this perfectly: any natural feature like the slope of a hill or shore of a coast can be broken down into smaller and smaller curves and angles, endlessly subject to refinement. In fractal geometry, which is driven by simple equations, the large curves mirror the small curves ad infinitum.
The emergent property is a matter of perspective, but that doesn’t make it simply an illusion or something not-real. The flatness of the tabletop is just as real—and more useful for setting out silverware and plates—than the churning atoms that actually compose it. The hill and its slope are just as real—and more useful for climbing—than the myriad tiny angles and curves, the surfaces of the grains of sand and bits of rock, that underlie the slope.
Emergent property works on greater scales, too. From space the Earth presents as a nearly perfect sphere, a blue-white marble decorated with flashes of green and brown, but still quite smooth. That spherical shape only becomes apparent from a great distance. Viewed from the surface, it’s easy enough for the eye to see a flat plane bounded by the horizon and to focus on hills and valleys as objects of great stature which, from a distance of millions of miles, do not even register as wrinkles.2, 3
The concept of emergent property still haunts me when I look at a piece of polished steel or glass: however bright, smooth, and reflective the surface may appear, it’s actually quite rough at the atomic level. Moreover, the surface is pitted with gaps, the empty spaces between atoms that are not molecularly bonded and so held apart by the positive or negative charges created by their outermost electron shells.4
Emergent properties come into play only when the action of thousands, millions, or billions of separate and distinct elements are perceived and treated as a single entity. “Forest” is an emergent property of thousands of individual trees. The concept of emergent properties can be extremely useful to describe some of the situations and events that we wrestle with daily.
Consider the complexity and intuitive vagueness that we encounter when dealing with the human “mind” and its complement, the “personality.” Point to a single thought or the result of a single firing neuron and you lose the concept of mind. Conversely, you can know a person intimately and believe you understand his or her deepest nature, and yet trying to describe the whole person by mentioning one, two, or even a handful of traits leaves you frustrated. The mind is an emergent property of the flow of sensations, reactions, and thoughts occurring in human awareness. For that matter, thoughts can be described as an emergent property of electrical signals in the brain. One signal does not make up a complete thought, only the interaction of many signals. One thought does not make up a mind, only the interaction and remembrance of many thoughts and experiences over time. Similarly, one choice or action, a single like or dislike, one spoken word or a telling silence, does not make up the personality.5 The nature of the individual only emerges as the summation of actions and choices held and compared in the perceiver’s memory.
The shape and function of cells are emergent properties of proteins orchestrated by the action of DNA. One gene or protein does not make a cell, only the interaction of many proteins. Similarly, the body and its functions is the collective property of millions or billions of cells. If you peel back the layers of cells—skin, fat, flesh, blood, bone—you do not arrive at a “true” center that is the “real” body. By taking away, you simply remove the reality of the emergent property in favor of the bits and pieces that comprise it. Similarly, if you peel back the layers of an onion, you eventually come to a green shoot with a hollow center, but that is no more the nature of the onion than the hollow ventricles of a human heart are the center of the human’s being.
Climate may be an emergent property of weather: patterns that recur with the seasons, storm and sunlight, evaporation and precipitation, high pressure pushing in behind low pressure. But one thunderstorm, or one season of storms, does not make a climate, only year after year of patterns recurring with variation. And one temporary input such as infalling solar radiation or a spike in humidity does not make a thunderstorm, only the interaction of many inputs working together.
The whole world around us, everything we can see at a human level, is the emergent property of molecular events. One molecular bond, joining or breaking, does not create the world, only the interaction of many bonds. In this case, the probability of any single event is the sum of the probabilities of the contributing molecular events. Similarly, a galaxy is the emergent property of its stars, and the shape of the universe an emergent property of the galaxies and the masses they contain.
The key point here is that looking for or arguing about the importance of one thought, one gene, one weather input, one molecular event in relation to the whole is usually futile. In some rare cases, a single gene mutation may give rise to a defective cell, or a single hurricane may temporarily change the weather over a region for a few weeks or a month. But among millions of mutations and thousands of storms the emergent property is … stability.
Systems tend to evolve in stability. Disruptions like thunderstorms or genetic mutations or temper tantrums tend to spend themselves and then the system returns to stability. The notion that single effects can trigger chain reactions, build momentum, and ultimately take over the system is an error of perception. Yes, a seed crystal dropped into a supersaturated salt solution can cause a sudden precipitation of solid grains. Yes, quickly bringing together two hemispheres of uranium each containing a high concentration of the U-235 isotope can cause an impressive explosion. Yes, repeatedly insulting the human genome with bursts of ionizing radiation or chemical irritants can cause a cancer to form. And yes, an incidence of frustration and resulting temper tantrum may herald a psychotic break. But in each case, the triggering effect exploits an instability—supersaturation, concentration, underlying genetic or psychological propensity—that leads to the sudden change. Systems don’t usually run away by themselves. And when they appear to do so, then the sudden deviation is an emergent property of the trigger impinging on systemic instability.
Reality is simply an emergent property of a sum of causes leading to a sum of effects. The universe generates and regenerates itself through complexity and interaction. Choirs of angels sing on atomic pinheads. We have so much to discover, to learn, and to appreciate!
1. And no, I don’t have a reference for it.
2. The popular notion that the sphericity of the Earth was only discovered by Columbus’s sailing west to go east is a myth. The Greek mathematician Eratosthenes measured the circumference of the planet in 240 B.C. by comparing the angle of the noonday sun and the shadows it cast at the summer solstice in his hometown of Alexandria and at the city of Aswan in southern Egypt. And sailors have long been able to intuit the curvature of the surface, because they can see ships disappear over the horizon—going “hull down”—while their masts and sails stay plainly in sight. And then again, a sailor who climbs his own mast can see farther, and see more of that ship on the horizon, than one standing on the deck. The planet has given us clues to its true nature since antiquity.
3. The surface roughness of the Earth, compared to the surfaces of objects manufactured to high tolerances like ball bearings and billiard balls, is a matter of some conjecture. The Earth’s surface deviations from, say, the Marianas Trench (6.8 miles deep) to the top of Mount Everest (5.5 miles high), are about 100 times the deepest scratches on a cue ball that would still be allowed in tournament play. So the planet would make a poor ball bearing in some giant’s Erector Set. But if you could pick it up and handle it with that giant’s fingers, the planet would feel almost as smooth.
Of course, surface roughness is different from the planet’s roundness, and there the Earth is quite distorted, or oblate, due to the pull generated by its spin. The diameter measured across the equator is greater than the diameter measured along the axis of spin by about 27 miles. But that deviation is still small enough that it only became apparent when we started going into orbit and taking detailed measurements.
4. An old thought experiment in physics holds that if, by some vanishingly rare coincidence of alignment, the empty space between the atoms in your finger could momentarily line up with the atoms comprising the tabletop, and vice versa, you could push your fingertip right through the surface. (Of course, if those gaps suddenly shifted while your finger was so inserted, the result would be quite painful.) But then, you can never really touch the table’s surface at all, because the electron charges of those surface atoms repel your fingertip in the same way they repel the other atoms in the tabletop.
5. And yet, as every novelist knows, a single choice, action, or word can have great effect in the world of affairs and change the course of a lifetime.