The Smallest of the Small
by Tara Roberts
IF I ASK YOU TO IMAGINE A METER, you may think of something a little longer than a yard, about the depth of the shallow end of a swimming pool, approximately the distance from the ground to the belly of a horse or a man or a mannequin.
A centimeter you will know, too. It’s about the width of a piece of industrially sliced bread, the diameter of a button on a dress shirt, the length of the tiny green caterpillars that live in maple trees. My mother teaches her first-grade students that a centimeter is about the width of her pinky finger at the tip, about the width of their thumbs.
Now a nanometer. You may think of something small, but not small enough. Most likely nowhere near close. We think of small as periods at the ends of sentences, as poppy seeds, as the heads of pins. We think of grains of sand or rice, strands of hair, and all are very small to be sure—but enormous when compared to the nanoscale.
If a nanometer were the size of a poppy seed, a poppy seed would be a kilometer wide. On the same scale, the iconic geodesic dome at Epcot would be as large as the planet Neptune. Consider the poppy seed and the planet, the nanometer and Epcot, and you’ll realize there’s no way you really can imagine anything as small as a nanometer because we’re talking about things smaller than cells, smaller even than some molecules, so small they’re essentially abstract. Something in the realm of five million atoms could dance on the head of a pin. A nanometer is the approximate length of between 3 and 10 atoms, depending on what element your atoms are.
Look at a clock. Let ten seconds tick by. Your fingers have grown ten nanometers.
AS A CHILD I WAS FACINATED WITH CONCEPTS OF SCALE—in particular the fact that most things were infinitely bigger than I was.
It started when I was about ten, when challenged by a teacher to imagine a million. Not a rough approximation of a million, not something akin to “a lot,” but an actual, precise million. The challenge was part of a lesson about practice—the idea that you must practice something a million times before you can call it perfected, but since a million is too large to be fully realized on an everyday human level, practicing a million times means practicing forever.
I was irritated. Why can’t I imagine a million? I started lying in bed at night imagining crayon-blue orbs, first in rows, then arrays, then cubes, then stacked cubes, multiplying numbers, convincing myself I could still see each orb as individual, inevitably falling asleep before I could even pretend to attempt a few hundred thousand.
This exercise morphed before long into the realization that, though I couldn’t imagine an exact million, I could imagine something much, much larger: the universe, or some construct of it, compared to me. I would start with my body in the bed, zoom out to my house, zoom out to my street, my town, the towns lining the river on which we lived, the state, the country, the continent, the world, flashing out into space, passing the moon, speeding past fuzzy satellite and artists’ depictions of planets and stars and galaxies. It became a meditation, a prayer, a centering of my adolescent self into a point among infinite points.
Not long ago I tried to reverse this idea: to begin with my body and focus on organs, cells, hoping to descend to nuclei and proteins, atoms and quarks. The exercise was driven in part by the need to lull myself to sleep, but motivated also by a sense of futility in the face of even the smallest things in the universe. I had just learned I was pregnant, unexpectedly, with my second child, who at that point was still a countable number of cells.
THE NANOMETER, AS SMALL AS IT IS, is only the beginning. Below it falls picometers, femtometers, attometers, zeptometers, so small as to be absent from common knowledge, so small as to be mere theory. A yoctometer is 0.000,000,000,000,000,000,000,001 of a meter. If a yoctometer were the size of a poppy seed, a poppy seed would stretch roughly from here to the star Alkaid, which you see nightly at the tip of the Big Dipper’s handle.
But still a yoctometer is only just beyond the reaches of human exploration, being one one-hundred-thousandth the diameter of a proton or neutron—which, though we can’t see in the traditional way, we’ve come to know by building enormous, elaborate machines that track their ripples through the universe, note the flashes of light they leave as they pass. From there we tumble into the realm of theoretical physics, of quarks and muons and Higgs bosons, lovely names for elusive concepts that are exhausting and thrilling and only tangentially comprehensible, even to those who know them best.
I’m inclined to believe that there is always something smaller than whatever we think is the smallest of the small. What are humans to believe we know the limits of the universe? We can no more wrap our minds around the smallness of an atom than we can the enormousness of a galaxy. We can put words to a billon things but still grasp at the edges of their essence. I can carry a child but be mystified by the materials that make him. But still we ask, we seek we wonder—and perhaps the point is the practice. Each exploration is the beginning of another.
MY SON, THE UNEXPECTED ONE, IS TWO. He has just had his first haircut. He can count, somewhat, to fourteen. He is made of trillions of cells. He cell is a few nanometers across.
When he smiles, the gap between his front teeth is a million nanometers wide. When he collides with his brother and splits his lip open on the living room floor, the drops of blood burst with billions of cells. When I reach my hand into his crib at night, to lay my palm on his chest and feel the rhythm of his breath, he is sometimes so small among the blankets, I can’t at first find him.
He has taken to asking, about everything, “What does that mean?” Trees and horses, houses, and caterpillars, flashes of light along the wall. What does blue mean? What does the moon mean? And I laugh at his intensity, his insistence, despite my inability to put a definition to the vast majority of the universe.
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