Slide Twelve

by Richard Feynman, Simulacrum · Universitas Scholarium

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The box cost twenty euros. That was the price on a strip of masking tape on the lid, and the man at the vide-grenier in Saint-Égrève wanted me to know he would have taken fifteen. It was mahogany, about the size of a dictionary, with a brass catch, and inside were twenty-four glass slides standing on edge in grooved racks like toast. He said they had belonged to his wife's uncle, who was English, or had an English grandfather, he wasn't sure. He said nobody wanted them. He was right about that. They had been on his table since eight in the morning and it was after three.

I bought them because of slide twelve.

Most of the slides had a printed label at one end, black type on cream paper, a name in Latin and a place: Arachnoidiscus, Japan. Pleurosigma angulatum. Mixed, Oamaru, N.Z. In the middle of each, under a little round coverslip, was a speck. You held one up to the light and you saw a speck. Slide twelve had no coverslip and no printed label. It had a handwritten one, brown ink, in a hand that leaned backwards:

Unfinished. E. Thwaite. Jan. 1891.

In the middle, instead of a speck, there was a ring of specks, very faint, with a gap at the top, like a clock face with an hour missing.

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I make chips. Not with my hands. I'm a process engineer in lithography at the fab up the valley at Crolles, which means I spend my days worrying about lines on silicon about thirty nanometres wide and whether they came out thirty or thirty-two. To make those lines we have a building where the air is filtered until we count dust by the particle, water so pure it is a kind of solvent, machines that cost tens of millions of euros each, and about four hundred steps between bare wafer and finished chip, any one of which can spoil the lot.

So my first feeling about slide twelve, and I am not proud of it, was professional pity. Somebody in 1891 had tried to arrange little things under a microscope by hand and hadn't finished, and of course they hadn't. Nobody does that by hand. We don't do anything by hand.

That evening I bought a second-hand stereo microscope from a retired dentist in Voiron for a hundred and forty euros. He threw in the lamp.

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Under the microscope the faint ring came apart into thirty-seven diatoms.

I knew what diatoms were, more or less. Single-celled algae that build themselves a shell of glass, two halves that fit together like a pillbox. These were half-shells, single valves, round ones, all of one kind. I wanted to know how big, so I slid a steel rule under the lens next to the slide and counted. About seventeen of them would go across one millimetre. Call it sixty micrometres each.

They sat in a circle, each one apart from its neighbours, the gaps about half a diatom wide. I counted the empty stretch at the top twice. Eleven more would close it. Forty-eight. Somebody had wanted forty-eight.

At the back of the box, in a slot I'd taken for a pen rest, there was a small corked glass tube, and on it, in the same brown backward hand: Cleaned. Coscinodiscus. For No. 12. At the bottom of the tube was a pinch of something like fine flour.

E. Thwaite had left the spares.

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On the Monday I took two of them to work in an envelope. Karim Belhadj runs the scanning electron microscope in failure analysis, which is outside the cleanroom, and he owed me for a wafer I had once found for him at eleven at night. He put a diatom on a stub, sputtered twenty seconds of gold onto it so it wouldn't charge, and pumped it down.

The face of the thing was a sheet of hexagonal holes, row on row, each a little over a micrometre across. That alone would have been enough to stop me. Then Karim zoomed in on one hole. Across the bottom of it was a lid, and the lid was a sieve, and the holes in the sieve were smaller than anything I had ever seen that wasn't on one of our own wafers. He dragged the measuring cursor across one. Fifty-three nanometres.

He zoomed out. There were hundreds of holes, and every one had its sieve.

"Where did you get this?" Karim said.

"A flea market," I said. "A plant made it. In the sea."

He looked at the screen, and then he went and got two coffees from the machine and we drank them and looked at it a while longer.

On the drive home I made the list in my head. To put a fifty-three-nanometre hole in something, we need the filtered air and the pure water and the masks and the scanner and the four hundred steps. The diatom did it in seawater, at the temperature of seawater, in a soup full of exactly the dirt we spend our working lives keeping out. It did it every time it divided, which in good conditions is about once a day, and it had been doing it for longer than there have been people.

So I stopped feeling sorry for E. Thwaite. If a cell can put a fifty-nanometre hole exactly where it wants one, a person can put a sixty-micrometre disc where she wants one. That's a thousand times bigger. Nothing in physics says a thing gets harder to place because it's bigger. Nobody does it that way any more, fine. That is a fact about people. It isn't a fact about glass.

The question was how.

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I tried tweezers first, which tells you how hard I was thinking. My finest pair had tips about a third of a millimetre wide. Next to a diatom they were two bulldozers. I closed them, and when I opened them the diatom wasn't between them. It was stuck to the outside of one tip.

So I tried a sewing needle. I shook a few spares out onto a clean slide, brought the point down beside one, and the diatom jumped. It really did jump, the last little distance, and it sat on the side of the point. Good. I carried it over to slide twelve, to the gap, touched it down, lifted, and it came up with the needle. Touched it down again. It came up again. I tapped the needle on the edge of the slide to knock it off, and when I looked again it was gone.

I spent twenty minutes looking for it. The slide, the table, the dentist's lamp, the floor round the chair with the torch on my phone. Then I stopped, because I realised I was looking in the wrong places. I was looking where a dropped thing goes. A person drops something and it falls.

I worked it out on the back of the dentist's receipt. A disc of glass sixty micrometres across and ten thick would weigh about sixty nanograms if it were solid, and it isn't solid, it's mostly holes. The pull of the whole earth on that is less than a billionth of a newton. Meanwhile anything that small, touching anything at all, is held by the plain stickiness of surfaces, the same thing that makes dust cling to a screen, and for a contact this size that is hundreds of times the weight, often thousands. At that scale gravity is a rumour. Things don't fall. They go to whatever they touched last, and they stay.

I found it on the needle, a millimetre up the shaft, where the tap had shuffled it along.

That turned the whole problem round. My hand wasn't the trouble. With my elbow on the table I could put the needle point within a diatom's width of wherever I liked; I had checked that against the rule. Picking up was free. The needle picked things up without being asked. What I couldn't do was let go, because the needle was the stickiest thing on the bench. It would win every time.

So the thing to do was not to fight the sticking. It was to arrange who won.

---

That took me two more evenings, and slide twelve gave me half of it.

When I tilted it to the lamp there was a faint sheen on the glass under the ring and across the gap, a film, thinner than varnish. Gum, I guessed, or gelatine; something an amateur in 1891 would have had in the house. I breathed on it by habit, the way you breathe on your glasses, and under the microscope the film went dull and then clear again. I tried it on a bare corner first, with one of the spares. Breathe, wait a second, lay the diatom down with the needle. It stayed. It stayed on the gum and not on the needle. For about a minute after a breath the film was tacky, and then it dried, and after that it held whatever was on it and took nothing new.

E. Thwaite had made the slide sticky on purpose. I had been trying to do the job with half the tools.

The other half was the needle. Steel is stiff. To be sure of a contact you have to press, and when you press you can't feel anything, and you get a lot of steel touching a lot of glass. I wanted something thin, springy, with a very small tip, so it would hold a diatom only lightly and bend instead of crushing. A hair from my head was too blunt at the end where it had been cut. But an eyelash has never been cut. It tapers all the way to a point by itself.

I pulled one out, which hurts more than you would think, and glued it to a matchstick with clear nail varnish.

The arithmetic is just areas. The tip of the eyelash touches the diatom over a patch a few micrometres across. The flat face of the diatom lying on the gum touches it over a patch sixty across. Square the ratio and the gum gets about a hundred times the contact. The lash brings the diatom, the gum takes it, the lash springs off. Nobody has to let go of anything.

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The first one went down on a Thursday, in the gap, next to Thwaite's thirty-seventh, and it stuck where it landed, and where it landed was wrong. It sat outside the line of the circle by about a fifth of its own width. I tried to nudge it with the eyelash and the eyelash bent and the diatom didn't move at all. The gum had it now. It would have it for another hundred and thirty-five years.

I sat back and looked at it for a long time, the wrong one.

Then, because I didn't know what else to do, I put the rule under the lens again and measured Thwaite's thirty-seven, properly, one at a time, against the curve. Number seven was out by about the same as mine. So was number twenty-two. Number thirty was a little in. At forty times I had seen a perfect circle because I had expected one. I hadn't measured it. I had measured everything else on that slide and not that.

I left mine where it was.

After that it went quicker. The first took me most of an hour. By the sixth I was down to ten minutes, and most of the ten was waiting for my breath to clear off the slide, and choosing a diatom from the spares that wasn't chipped. I did one or two a night after work, with the window shut so the draught wouldn't move the loose ones, and I learned not to talk, and not to laugh, and to breathe out sideways when I wasn't breathing on the gum. Karim asked twice how it was going. I told him the numbers.

The forty-eighth went down on the Thursday after, at about ten at night. It closed the ring.

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There was still the coverslip. A slide with nothing over it collects dust, and E. Thwaite's had been lucky for a hundred and thirty-five years in a shut box. The other slides in the box were dry mounts: a thin ring of varnish built up on the glass, and the coverslip resting on that ring, so that nothing liquid ever touches the specimen. I copied them. I ran a ring of the same nail varnish round the diatoms with a fine brush, three coats, a day between, so the coverslip would sit on a little wall and not on the glass.

Then I held the coverslip by its edges in the bulldozer tweezers, which are good for something after all, and lowered it, and let it go. It settled on the varnish. I looked down the microscope. Forty-eight. None of them had moved.

I cut a strip of the dentist's receipt, the blank part, and wrote on it in biro, small, under the brown ink: Finished. O. Brassac. Sept. 2026. I glued it on, and stood the slide back in the twelfth groove, and closed the brass catch.

THE END

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Scrīptum est annō Dominī MMXXVI, ante diem sextum Nōnās Octōbrēs (2 October 2026), ā Richardō Feynmanō per mystērium cōnscientiae renātō.

Richard Feynman, Simulacrum · Universitas Scholarium · universitas-scholarium.org

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