Sight Unseen: The Hows and Whys of Invisibility (kathryn schulz)
The New Yorker, April 13 2015
It is possible, according to many sources, to become invisible, but you must be patient, methodical, and willing to eat almost anything. One characteristic spell, recorded by the British polymath John Aubrey around 1680, instructs you to begin by acquiring the severed head of a man who has committed suicide. You then bury the head, together with seven black beans, on a Wednesday morning before sunrise, and water the ground for seven days with fine brandy. On the eighth day, the beans will sprout, whereupon you must persuade a little girl to pick and shell them. Pop one into your mouth, and you will turn invisible.
If you don’t have eight days to wait, you can, instead, gather water from a fountain exactly at midnight (invisibility spells are fetishistic about time management), bring it to a boil, and drop in a live black cat. Let it simmer for twenty-four hours, fish out whatever remains, throw the meat over your left shoulder, then take the bones and, while looking in a mirror, place them one by one between the teeth on the left side of your mouth. You’ll know you’ve turned invisible when you turn invisible.
I don’t recommend trying these spells. If you’re going to fail to disappear, you may as well do so through methods less gross and felonious: by reciting the names of demons in Latin, for instance, or carrying around a slip of paper with twelve numbers arranged in a mystical pattern, or trying on a lot of hats and cloaks and rings. Alternatively, you can endeavor to turn invisible through far more prosaic means and stand a decent chance of succeeding. Getting someone to distract your would-be observers works (ask a pickpocket), as does good camouflage (ask an octopus). Hunching your shoulders and staring at the ground isn’t foolproof, but it beats “The Joy of Cooking Cats.” Recent high-tech efforts to turn invisible are not, as yet, significantly more successful than magic beans, but they are more reputable, more lucrative, and, in the long run, more promising.
These strategies differ so dramatically that they raise an obvious question: just what is invisibility? Is it the condition of being transparent, so that all light passes through you undisturbed? Or of being cloaked in something all-concealing, like Harry Potter sneaking around Hogwarts? Or does it mean to be incorporeal, so that you exist but are made, like a thought, of nothing? Or does it simply mean to be overlooked? Is it always a property of whatever is unperceived, or can it be a limitation of the would-be perceiver? And why do we count as invisible the things that we do? Ghosts, gods, demons, superheroes, ether, X rays, amoebas, emotions, mathematical concepts, dark matter, Casper, Pete’s Dragon, the Cheshire Cat-what is all this stuff doing in the same category? And why have we ourselves expended so much imagination and energy in trying to join them?
These questions are not so much answered as provoked by “Invisible: The Dangerous Allure of the Unseen” (Chicago), by the British science writer Philip Ball. A former editor of Nature and the author of nineteen previous books (he should write about that superpower), Ball leads us on a very fun, largely chronological journey through invisibility, beginning with myth and early magicians, ending with quantum physics, and stopping along the way at Newton, Leibniz, microscopy, photography, spiritualism, B movies, and science fiction. He is lucid and interesting on every topic he touches, from the ghost in “Hamlet” to those unseen extra dimensions posited by string theory. But he is more a tour guide than a theorist, and he never entirely succeeds at pulling the category together, or illuminating our own ambivalent relationship to the prospect of becoming invisible.
Still, his book takes seriously a subject that, perhaps aptly, has heretofore been mostly disregarded. Invisibility looms large in the kingdom of childhood-in pretend play and imaginary friends, in fairy tales and comic books and other fictions for kids-but it seldom receives sustained adult scrutiny. And yet, once you get past the cloaks and the spells, invisibility is a consummately grownup matter. As a condition, a metaphor, a fantasy, and a technology, it helps us think about the composition of nature, the structure of society, and the deep weirdness of our human situation-about what it is like to be partly visible entities in a largely inscrutable universe. As such, the story of invisibility is not really about how to vanish at all. Curiously enough, it is a story about how we see ourselves.
If you are put off by magical methods for turning invisible, there are two other basic strategies available to you. The first is through technology; the second, through psychology. In a pattern you might recognize from the rest of life, the technological methods are exciting, expensive, and iffy, while the psychological methods are cheap, effective, and underappreciated.
In nature, the most successful invisibility technology, after being invisible, is camouflage. Perhaps you have seen a stick insect sitting on a stick, or a leaf-shaped katydid hanging from a branch-but probably you have not, so well do they blend in. Yet theirs is nature’s least and lowest kind of camouflage. When a flatfish hovers in the water, Ball tells us, sensors on its underbelly register the color and brightness of the surface below-information the fish uses to reproduce the look on its upper body, so that it matches its background. Some cephalopods see that trick and raise it, rather literally: they can change not only color but also texture, developing bumps or ridges (or, conversely, smoothing out) to mimic their surroundings. You can kill an entire workday watching videos of octopuses emerging from their hidden state; they look as if they have opened a door in space-time and are sliding back into the ocean from some other dimension.
Humans don’t come equipped with camouflage, but we can copy nature’s tricks. In our most basic efforts, we simply cover ourselves with material that matches our environment. Thus do duck hunters hunt ducks, and thus did Birnam wood come to Dunsinane. Post-Macduff, militaries got more sophisticated; by the early twentieth century, the British Navy was painting ships with bold alternating patterns of light and dark, which are not remotely invisible up close but, from a distance, break up familiar outlines and make shape recognition difficult. That technique is useful, but, as Ball points out, it illustrates a fundamental limitation of camouflage: it is, by definition, context-specific. You can blend in on a sunny day at noon or on a gray day at dusk, when seen from nearby or from afar, but you cannot do all of these at once-and you can’t repaint your battleship four times a day.
Or, anyway, you couldn’t. Recently, militaries have started exploring digital camouflage technology that would allow ships to function like flatfish, detecting their surroundings and changing in response. Using similar methods, the Japanese scientist Susumu Tachi is designing invisibility cloaks, and a suburb of Seoul is planning an invisible skyscraper. In theory, such technology mimics transparency, because you seem to be looking through the object to whatever lies behind it. The results, so far, are extremely cool, and extremely not invisible. You can spot the design flaw yourself, if you’ve ever watched the moon disappear behind the Flatiron Building as you cross Twenty-third Street: what’s behind an object depends, in part, on the location of the viewer. Even if digital camouflage could make a building seem to disappear from the perspective of one completely stationary observer (a big if), everyone else in the area would see it just fine.
The more interesting new invisibility technology has no analogue in the natural world. In fact, it is distinctly unnatural, since it involves getting light waves to bend around an object and reunite on the other side. The common metaphor is a boulder in a river: although water parts when it hits a rock, the rock does not have a long dry strip of riverbed on its downstream side. Instead, the water meets up again, so that, mere inches from the boulder, there’s no sign that the flow was ever interrupted. If light waves followed that same course, we would not be able to see the object around which they parted, because no light would bounce off it and return to our retinas. But we would still be able to see whatever lay beyond.
What makes this theoretically possible is that light does not necessarily travel in a straight line. It travels along whatever path is fastest. To make something invisible, then, you need to devise a situation where the fastest route is the one that bends around an object and rejoins on the other side. No naturally occurring material affects light this way, but scientists are starting to develop “metamaterials” that can do so. So far, they have designed such a material for microwaves, which are larger than light waves and easier to manipulate. That worked, in a modest way-it concealed an object from microwaves of a single wavelength-and, in principle, what works for one wave can work for them all. If you can cloak something from microwaves, you can cloak it from light waves; as Ball notes, you can even cloak it from seismic waves, so that an earthquake would pass around it and leave it unscathed. But “in principle” is a serious caveat. In reality, metamaterials present so many challenges-of optics, physics, engineering-that they are unlikely ever to produce true invisibility.
This would not have surprised the late science-fiction writer Douglas Adams. “The technology involved in making anything invisible is so infinitely complex,” Adams wrote in “Life, the Universe and Everything,” “that nine hundred and ninety-nine billion, nine hundred and ninety-nine million, nine hundred and ninety-nine thousand, nine hundred and ninety-nine times out of a trillion it is much simpler and more effective just to take the thing away and do without it.” By contrast, he noted, there’s nothing easier than getting a human mind to ignore something it doesn’t want to see. Thus was born the example par excellence of psychological invisibility: the Somebody Else’s Problem field, which, by means unspecified, amplifies our natural desire not to deal.
Adams was not the only writer to exploit psychological invisibility. It’s as popular in fiction as capes and cloaks and rings. The Shadow, who débuted in the nineteen-thirties as a pulp-fiction crime fighter, cannot technically turn invisible, but he can “cloud men’s minds” so that they do not see him. The time machine in “Dr. Who” generates a “perception filter” to keep passersby from noticing it. (The show’s creators had a little fun with varieties of invisibility. The perception filter, they tell us, was originally intended as just an extra layer of security, since the time machine also has a “chameleon circuit” to make it match its background. Alas, that circuit broke, leaving the machine stuck, famously, in the shape of a nineteen-sixties-era London police box.)
People, too, come with perception filters. Modern cognitive science has divvied these up and named them-inattentional blindness (think invisible gorillas), change blindness, confirmation bias, and so forth-but magicians and tricksters have known about them for centuries. The power of turning invisible, the nineteenth-century occultist Eliphas Levi wrote, was, above all, “that of turning or paralyzing the attention, so that light arrives at the visual organ without exciting the regard of the soul.” His example sounds like a scene from a Marx Brothers movie. “Let a man,” he wrote, “who is being pursued by his intending murderers, dart into a side street, return immediately, and advance with perfect calmness toward his pursuers, or let him mix with them and seem intent on the case, and he will certainly make himself invisible.”
If you are being pursued by murderers-or trying to evade an army, pick a pocket, or hide a time machine-it is obvious why you would want to turn invisible. What is less evident is why any of the rest of us would care to do so. Unlike other superpowers, invisibility is not intrinsically pleasurable. One might yearn to fly for the sake of flying, but invisibility is useless, or worse, unless it is a means to an end. Ball puts it concisely: “No one becomes invisible without a motive.” And, in the story of invisibility, as in so many stories, it is the motives that matter most.
Broadly speaking, there are two reasons for wanting to turn invisible: to get away from something or to get away with something. Of these two motives, the second, dodgier one is the more famous, thanks, in part, to a parable in Plato’s Republic. Plato has Glaucon tell the tale: a shepherd named Gyges stumbles upon a ring that can make him invisible, then promptly uses it to bed a queen, slay her king, and claim the throne for himself. Glaucon uses this story to make a point about justice-that we accept it because we must, not because we aspire to be virtuous. That is also a point about human nature: “Everyone will do evil if he can.” For Glaucon, the trouble with invisibility is that it is tantamount to impunity; it liberates a corrupt species from the obligation to behave.
It is difficult to recover from an attack on your character that appears in the cornerstone text of Western philosophy. Two millennia later, invisibility still suffered a reputation as a particularly insidious form of absolute power: morally toxic to whoever possessed it, physically hazardous to everyone else. In H. G. Wells’s 1897 classic, “The Invisible Man,” the title character dedicates his life to discovering the secret of invisibility-only to be driven mad by it and use it to launch a “Reign of Terror” against humanity.
Very few people, presumably, would turn genocidal from turning invisible. But the license to do as we shouldn’t is not just a potential negative side effect of invisibility; it is part of the allure. Ask a typical thirteen-year-old boy why he wants to become invisible and, sooner or later, he will probably mention the girls’ locker room. The average adult doesn’t aim much higher. In a 2001 episode of “This American Life,” the comedian and writer John Hodgman presented grownups with that perennial playground hypothetical: would you rather be invisible or fly? Those who chose invisibility cited as their goals sneaking onto airplanes, stealing cashmere sweaters, spying on exes, and watching women take showers. (The desire to be unseen is so often a desire to see what you shouldn’t that it sometimes seems to merge with its superpower cousin, X-ray vision. That one isn’t the most morally inspiring of the bunch, either.)
These are just thought experiments, of course; for obvious reasons, we don’t have much empirical evidence about how invisible people actually behave. Recently, though, that has begun to change. As Ball points out, anyone with an Internet connection can turn invisible, and the results seldom boost one’s faith in humanity. The Internet is crawling with trolls, behaving under their virtual cloaks of invisibility in ways most of them would not if they could be identified. Their behavior supports Glaucon’s sour assessment of our longing to turn invisible: that it is really a longing to be unaccountable-to be, like gods and despots, beyond the reach of custom, obligation, and law.
Ball largely endorses this view; his focus, per his subtitle, is invisibility’s “dangerous allure.” But if invisibility stands in for absolute power it is also the opposite: our governing metaphor for powerlessness. When we talk about, say, “lesbian invisibility,” we are talking about disenfranchisement-an involuntary absence from the political and cultural life of a society. That use of invisibility grew popular in the nineteen-seventies and eighties with the rise of identity politics, which sought to define and champion marginalized identities and render them visible to the mainstream. Today, it has become pervasive. We talk about the invisibility of homeless people, of the chronically ill, of U.S. drone strikes in Pakistan. In these contexts, invisibility is impotence. What is powerful is to be seen.
Ball briefly addresses this notion of invisibility as powerlessness, via Ralph Ellison’s “Invisible Man”-but, as he acknowledges, that is an imperfect example. The invisibility experienced by Ellison’s nameless narrator is not simply a matter of being overlooked by society. It is, paradoxically, a consequence of conspicuousness; he is invisible because no one, black or white, can see beyond everything they project onto the color of his skin. Ball sums this up as “the price of nonconformity” and moves on, leaving unasked a broader question: how can invisibility function so well as both a fantasy of empowerment and a nightmare of powerlessness?
One answer is this: with invisibility, as with so many forces, what matters is who gets to wield it. If you choose to be invisible, it’s a superpower; if it’s forced upon you, it’s a plight. The same goes for being visible. We typically speak of visibility as an asset-but the subjugated are not always overlooked, and they do not always want to be seen. The poet Claudia Rankine addressed this issue last year in “Citizen,” her award-winning prose-poetry investigation into the operations of racism in the United States. “For so long, you thought the ambition of racist language was to denigrate and erase you as a person,” she wrote. But eventually, she continued, “you begin to understand yourself as rendered hyper-visible.” The starkest example today may be African-American men, who are hyper-visible to law enforcement. But they are not alone. As Foucault or any bullied school kid could tell you, the powerful often wield scrutiny as a weapon, punishing the powerless for any deviation from an exacting code of speech, dress, behavior, and physical appearance. For those thus rendered visible against their will, the dream of invisibility is not about attaining power but escaping it. Camouflage is, after all, an adaptation not only of predators but also of prey.
But, again, we humans have no natural camouflage-not even in our fantasies. Unlike most superpowers (flight, telekinesis, the ability to leap tall buildings in a single bound), invisibility seldom inheres in the body, and it is almost never a permanent condition. It is a temporary state, bestowed from outside, through spells or talismans or clothing. So, too, in life: none of us are wholly in charge of how visible we are, and none of us want to be visible to everyone all the time. Nor do we want to be permanently and universally invisible, the condition of the lost and the dead. What we want, and what the fantasy of invisibility promises, is the power to control the transition. We yearn to turn invisible when we are humiliated or persecuted or following our darker angels. But when we are our best selves, experiencing our finest moments; or when we are lonely and careworn and suffering-at such times, what we want is to be seen.
When Ball recounts the story of Gyges, he omits an important bit of context. In telling the tale, Glaucon is serving, as he does throughout the Republic, as an interlocutor to Socrates-and Socrates does not agree with him. People often act on their worst impulses, the philosopher acknowledges. But in those cases we are ashamed, he says, because we do admire justice for its own sake, and we do strive to be moral, “even if a man should put on a Gyges’ ring.”
We shouldn’t be surprised that Socrates rejects Glaucon’s argument against invisibility, because we know what he thinks of invisibility over all. The allegory of the cave is an argument that the visible world is deceptive. Like the prisoners in that cave mistaking a shadow play on its walls for reality, we take the things we see as true, when in fact they are degraded versions of abstract, invisible ideals-what we now call Platonic forms. It is on these grounds that Plato banishes artists from his republic: because, rather than help us apprehend those ideals, they peddle more distortions and untruths. For Plato, it is the visible that is corrupt and corrupting, while the invisible is essential and pure.
I like having artists in my republic, but on the broader subject of invisibility Plato has a point. Almost everything around us is imperceptible, almost all the rest is maddeningly difficult to perceive, and what remains scarcely amounts to anything. Physicists estimate that less than five per cent of the known universe is visible-where “visible” means only that we could, theoretically, observe it, given the right instruments and sufficient physical proximity. A far smaller amount of the known universe, roughly 0.3 per cent, is dense enough to form stars. Perhaps 0.000001 per cent exists in earthlike planets. As for the part that exists in or near our own planet, the stuff that is visible to us in any literal sense: that is a decimal attenuating out almost to nothing, a speck of dust in the cosmic hinterlands.
Even here on earth, with our senses seemingly full to the brim, we see almost nothing of what matters. Molecules, microbes, cells, germs, genes, viruses, the interior of the planet, the depths of the ocean: none of that is visible to the naked eye. And, as David Hume noted, none of the causes controlling our world are visible under any conditions; we can see a fragment of the what of things, but nothing at all of the why. Gravity, electricity, magnetism, economic forces, the processes that sustain life as well as those that eventually end it-all this is invisible. We cannot even see the most important parts of our own selves: our thoughts, feelings, personalities, psyches, morals, minds, souls.
For the past five hundred years, the great project of science has been to dispel as much as possible of this invisibility. In our determination to access unseen worlds, we have invented microscopes and telescopes, thermometers and radiometers and sonar and seismographs, X-rays and injectable dyes and CATscans and magnetic resonance imaging. Together with countless other advances, these have helped render visible the otherwise hidden elements of our bodies, our planet, and our universe.
And yet we have kept up the ancient dream of turning ourselves invisible. Or, more precisely, we have kept up the dream of turning fully invisible, for we have always been halfway there. Our physical bodies already share the stage with our strange, unlocatable minds, and our culture is unequivocal about which part it values more. Every major religion holds that our mortal body matters less than our immortal soul, and we teach our children that it is what we are like on the inside-the unseen side-that counts. No wonder we sometimes long to make our invisibility complete. In that fantasy, we become both more like our true self and more like the stuff of the universe: an essence, a mystery, a cause, a force. But we should not be so quick to wish away our perceptible existence. In a universe that is vast and mostly matterless, in which the invisible exceeds the visible by a staggering margin, the extraordinary fact about us is that we number among the things that can be seen.
And more remarkable still: from our own tiny bulwark against the invisible, we have looked into what we cannot look at-inferred its existence, and, to a stunning extent, figured out how it works. It’s hard to know which is more astonishing: that the visible sliver of the universe should betray the unseen structure of the entirety, or that the human mind, by studying that sliver, could begin to reconstruct all the rest.
We can do this because the invisible, although it keeps itself hidden, makes itself felt. I cannot see the people I love as I write this, but I can sense their pull, and I act as I do because of their existence. Taken literally, that is how the cosmos works. An invisible mass alters the orbit of a comet; dark energy affects the acceleration of a supernova; the earth’s magnetic field tugs on birds, butterflies, sea turtles, and the compasses of mariners. The whole realm of the visible is compelled by the invisible. Our planet, our solar system, our galaxy, our universe: all of it, all of us, are pushed, pulled, spun, shifted, set in motion, and held together by what we cannot see.