meno venti domande

Leggendo la rubrica di Nick Hornby sui consigli per la lettura, riportata da Internazionale, mi sono imbattuto in un gioco curioso, ideato dal fisico John Wheeler per spiegare il funzionamento della meccanica quantistica. Horny lo citava avendolo letto nel libro "The Conversations", un dialogo tra lo scrittore Michael Ondaatje e il montatore cinematografico Walter Murch.

Questo gioco è una variante del più conosciuto "venti domande": una persona lascia la stanza per qualche minuto, mentre gli altri presenti scelgono insieme un oggetto. Quando la persona ritorna, avrà venti domande a disposizione per indovinare l'oggetto. Nella versione di Wheeler, invece, le persone che rimangono nella stanza scelgono un oggetto privatamente, ognuno il suo, senza dirlo agli altri. Quando il gioco delle "meno venti domande" comincia con la prima domanda, la risposta che verrà data influenzerà non solo la persona che deve indovinare l'oggetto, ma anche tutti gli altri, che dovranno scegliere un'altro oggetto se quello prescelto in precedenza non soddisfa la risposta data da un loro compagno in precedenza.

Il bello di questo gioco è che nessuno sa cosa gli altri stiano pensando, ma nonostante questo il gioco procede comunque e spesso, anche se non sempre, si arriva all'individuazione di un oggetto che soddisfa la scelta fatta da tutti. Quello che però mi ha affascinato è come Murch lo prenda ad esempio per spiegare come funzioni la creazione di un film. Citando dal blog di Philip Graham, dove ho trovato la spiegazione del gioco: "Il casting influenzerà come il costumista vestirà il protagonista, cosa che a sua volta influenzerà il design del set da parte del direttore artistico, influenzando a sua volta..." Nonostante tutte queste variazioni rispetto ad un'idea iniziale, in film prenderà comunque forma.

Simile potrebbe essere anche la stesura di un libro, come sottolinea Graham: non si parte dalla prima riga della prima pagina arrivando alla fine in maniera lineare. Spesso quello che era l'inizio si sposta più in là nel libro, a metà o magari verso la fine. Si interrompe la stesura di un capitolo per passare a lavorare su un altro grazie alle idee e alle influenze di quello che si è scritto finora, per poi tornare al capitolo incompleto e procedere in una maniera che all'inizio non si era prevista.

Ho trovato la trascrizione presa dal libro di Ondaatje, eccola qui sotto, in lingua originale.

(from The Conversations: Walter Murch and the Art of Editing Film)

Murch: There’s a great game–I forget whether we’ve talked about it–Negative Twenty Questions?

Ondaatje: No, we haven’t talked about it.

Murch: It was invented by John Wheeler, a quantum physicist who was a young graduate student of Niels Bohr’s in the 1930s. Wheeler is the man who invented the term “black hole”. He’s an extremely articulate proponent of the best of twentieth-century physics. Still alive, and I believe still teaching, writing.

Anyway, he thought up a parlour game that reflects the way the world is constructed at a quantum level. It involves, say, four people: Michael, Anthony, Walter, and Aggie. From the point of view of one of those people, Michael, the game that’s being played is the normal Twenty Questions–Ordinary Twenty Questions, I guess you’d call it. So Michael leaves the room, under the illusion that the other three players are going to look around and collectively decide on the chosen object to be guessed by him–say, the alarm clock. Michael expects that when they’ve made their decision they will ask him to come back in and try to guess the object in fewer than twenty questions. Under normal circumstances, the game is a mixture of perspicacity and luck: No, it’s not bigger than a breadbox. No,you can’t eat it….Those kinds of things.

But in Wheeler’s version of the game, when Michael leaves the room, the three remaining players don’t communicate with one another at all. Instead, each of them silently decides on an object. Then they call Michael back in.So, there’s a disparity between what Michael believes and what the underlying truth is: Nobodyknows what anyone else is thinking. The game proceeds regardless, which is where the fun comes in.

Michael asks Walter: Is the object bigger than a breadbox? Walter–who has picked the alarm clock–says, No. Now, Anthony has chosen the sofa, which is bigger than abreadbox. And since Michael is going to ask him the next question, Anthony must quickly look around the room and come up with something else–a coffee cup!–which is smaller than a breadbox. So when Michael asks Anthony, If I emptied out my pockets could I put their contents in this object? Anthony says, Yes. Now Aggie’s choice may have been the small pumpkin carved for Halloween, which could also contain Michael’s keys and coins, so when Michael says, Is it edible? Aggie says, Yes. That’s a problem for Walter andAnthony, who have chosen inedible objects: they now have to change their selection to something edible, hollow, and smaller than a breadbox.

So a complex vortex of decision making is set up, a logical but unpredictable chain of ifs andthens. To end successfully, the game must produce, in fewer than twenty questions, an object that satisfies all of the logical requirements: smaller than a breadbox, edible, hollow, et cetera. Two things can happen: Success–this vortex can give birth to an answer that will seem to be inevitable in retrospect: Of course! It’s the —-! And the game ends with Michael still believing he has just played Ordinary Twenty Questions. In fact, no one chose the —- to start with, and Anthony, Walter, and Aggie have been sweating it out, doing these hidden mental gymnastics, always one step ahead of failure. Which is the other possible result: Failure–the game can break down catastrophically. By question 15, let’s say, the questions asked have generated logical requirements so complex that nothing in the room can satisfy them. And when Michael asks Anthony the sixteenth question, Anthony breaks down and has to confess that he doesn’t know, and Michael is finally let in on the secret: The game was Negative Twenty Questions all along. Wheeler suggests that the nature of perception and reality, at the quantum level, and perhaps above, is somehow similar to this game.

When I read about this, it reminded me acutely of filmmaking. There is an agreed-upon game, which is the screenplay, but in the process of making the film, there are so many variables that everyone has a slightly different interpretation of the screenplay. The cameraman develops an opinion, then is told that Clark Gable has been cast in that part. He thinks, Gable? Huh, I didn’t think it would be Gable. If it’s Gable, I’m going to have to replan. Then the art director does something to the set, and the actor says, This is my apartment? All right, if this is my apartment, then I’m a slightly different person from who I thought I was: I will change my performance. The camera operator following him thinks, Why is he doing that? Oh, it’s because… All right, I’ll have to widen out because he’s doing these unpredictable things. And then the editor does something unexpected with those images and this gives the director an idea about the script, so he changes a line. And so the costumer sees that and decides the actor can’t wear dungarees. And so it goes, with everyone continuously modifying their preconceptions. A film can succeed in the end, spiralling in on itself to a final result that looks as if it has been predicted long in advance in every detail. But in fact it grew out of a mad scramble as everyone involved took advantage of all the various decisions everyone else had been making.