Tom Stoppard

​Excerpt from Act I - Scene IV

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[…]

VALENTINE: It’s how you look at population changes in biology. Goldfish in a pond, say. This year there are x goldfish. Next year there’ll be y goldfish. Some get born, some get eaten by herons, whatever. Nature manipulates the x and turns it into y. Then y goldfish is your starting population for the following year. Just like Thomasina. Your value for y becomes your next value for x. The question is: what is being done to x? What is the manipulation? Whatever it is, it can be written down as mathematics. It’s called an algorithm.

HANNAH: It can’t be the same every year.

VALENTINE: The details change, you can’t keep tabs on everything, it’s not nature in a box. But it isn’t necessary to know the details. When they are all put together, it turns out the population is obeying a mathematical rule.

HANNAH: The goldfish are?

VALENTINE: Yes. No. The numbers. It’s not about the behaviour of fish. It’s about the behaviour of numbers. This thing works for any phenomenon which eats its own numbers — measles epidemics, rainfall averages, cotton prices, it’s a natural phenomenon in itself. Spooky.

HANNAH: Does it work for grouse?

VALENTINE: I don’t know yet. I mean, it does undoubtedly, but it’s hard to show. There’s more noise with grouse.

HANNAH: Noise?

VALENTINE: Distortions. Interference. Real data is messy. There’s a thousand acres of moorland that had grouse on it, always did till about 1930. But nobody counted the grouse. They shot them. So you count the grouse they shot. But burning the heather interferes, it improves the food supply. A good year for foxes interferes the other way, they eat the chicks. And then there’s the weather. It’s all very, very noisy out there. Very hard to spot the tune. Like a piano in the next room, it’s playing your song, but unfortunately it’s out of whack, some of the strings are missing, and the pianist is tone deaf and drunk — I mean, the noise! Impossible!

HANNAH: What do you do?

VALENTINE: You start guessing what the tune might be. You try to pick it out of the noise. You try this, you try that, you start to get something — it’s half-baked but you start putting in notes which are missing or not quite the right notes … and bit by bit … (He starts to dumdi-da to the tune of “Happy Birthday”) Dumdi-dum-dum, dear Val-en-tine, dumi-dum-dum to you — the lost algorithm!

HANNAH: (soberly) Yes, I see. And then what?

VALENTINE: I publish.

HANNAH: Of course. Sorry. Jolly good.

VALENTINE: That’s the theory. Grouse are bastards compared to goldfish.

HANNAH: Why did you choose them?

VALENTINE: The game books. My true inheritance. Two hundred years of real data on a plate.

HANNAH: Somebody wrote down everything that’s shot?

VALENTINE: Well, that’s what a game book is. I’m only using from 1870, when butts and beaters came in.

HANNAH: You mean the game books go back to Thomasina’s time?

VALENTINE: Oh yes. Further. (And then getting ahead of her thought) No — really. I promise you. I promise you. Not a schoolgirl living in a country house in Derbyshire in eighteen-something!

HANNAH: Well, what was she doing?

VALENTINE: She was just playing with the numbers. The truth is, she wasn’t doing anything.

HANNAH: She must have been doing something.

VALENTINE: Doodling. Nothing she understood.

HANNAH: A monkey at a typewriter?

VALENTINE: Yes. Well, a piano.

Hannah picks up the algebra book and reads from it

HANNAH: “… a method whereby all the forms of nature must give up their numerical secrets and draw themselves through number alone.” This feedback, is it a way of making pictures of forms in nature? Just tell me if it is or it isn’t.

VALENTINE: (irritated) To me it is. Pictures of turbulence — growth — change — creation — it’s not a way of drawing an elephant, for God’s sake!

HANNAH: I’m sorry. (She picks up an apple leaf from the table. She is timid about pushing the point) So you couldn’t make a picture of this leaf by iterating a whatsit?

VALENTINE: (off-hand) Oh yes, you could do that.

HANNAH: (furiously) Well, tell me! Honestly, I could kill you!

VALENTINE: If you knew the algorithm and fed it back say ten thousand times, each time there’d be a dot somewhere on the screen. You’d never know where to expect the next dot. But gradually you’d start to see this shape, because every dot will be inside the shape of this leaf. It wouldn’t be a leaf, it would be a mathematical object. But yes. The unpredictable and the predetermined unfold together to make everything the way it is. It’s how nature create itself, on every scale, the snowflake and the snowstorm. It makes me so happy. To be at the beginning again, knowing almost nothing. People were talking about the end of physics. Relativity and quantum looked as if they were going to clean out the whole problem between them. A theory of everything. But they only explained the very big and the very small. The universe, the elementary particles. The ordinary-sized stuff which is our lives, the things people write poetry about — clouds — daffodils — waterfalls — and what happens in a cup of coffee when the cream goes in — these things are full of mystery, as mysterious to us as the heavens were to the Greeks. We’re better at predicting events at the edge of the galaxy or inside the nucleus of an atom than whether it’ll rain on auntie’s garden party three Sundays from now. Because the problem turns out to be different. We can’t even predict the next drip from a dripping tap when it gets irregular. Each drip sets up the conditions for the next, the smallest variation blows prediction apart, and the weather is unpredictable the same way, will always be unpredictable. When you push the numbers through the computer you can see it on the screen. The future is disorder. A door like this has cracked open five or six times since we got up on our hind legs. It’s the best possible time to be alive, when almost everything you thought you knew is wrong.