Le rabbin David Sedley nous rappelle une anecdote extraite de la biographie de Richard Feynman, un des plus grands physiciens du XXe siècle, intitulée Surely you're joking, Mr. Feynman![1].

Anecdote de Richard Feynman (en anglais) Anecdote de Richard Feynman (en anglais)

A footnote: While I was at the conference, I stayed at the Jewish Theological Seminary, where young rabbis - I think they were Orthodox - were studying. Since I have a Jewish background, I knew of some of the things they told me about the Talmud, but I had never seen the Talmud. It was very interesting. It's got big pages, and in a little square in the corner of the page is the original Talmud, and then in a sort of L-shaped margin, all around this square, are commentaries written by different people. The Talmud has evolved, and everything has been discussed again and again, all very carefully, in a medieval kind of reasoning. I think the commentaries were shut down around the thirteen or fourteen- or fifteen-hundreds - there hasn't been any modern commentary. The Talmud is a wonderful book, a great big potpourri of things: trivial questions, and difficult questions - for example problems of teachers, and how to teach - and then some trivia again, and so on. The students told me that the Talmud was never translated, something I thought was curious, since the book is so valuable.
One day, two or three of the young rabbis came to me and said, "We realize that we can't study to be rabbis in the modern world without knowing something about science, so we'd like to ask you some questions."
Of course there are thousands of places to find out about science, and Columbia University was right near there, but I wanted to know what kinds of questions they were interest in.
They said, "Well, for instance, is electricity fire?"
"No," I said, "but... what is the problem?"
They said, "In the Talmud it says that you're not supposed to make fire on a Saturday, so our question is, can we use electrical things on Saturdays?"
I was shocked. They weren't interested in science at all! The only way science was influencing their lives was so they might be able to interpret better the Talmud! They weren’t' interested in the world outside, in natural phenomena; they were only interested in resolving some question brought up in the Talmud.
And then one day - I guess it was a Saturday - I want to go up in the elevator, and there's a guy standing near the elevator. The elevator comes, I go in, and he goes in with me. I saw, "Which floor?" and my hand's ready to push one of the buttons. "No, no!" he says, "I'm supposed to push one of the buttons for you.
"What?"
"Yes!" The boys here can't push the buttons on Saturday, so I have to do it for them. You see, I'm not Jewish, so it's all right for me to push the buttons. I stand near the elevator, and they tell me what floor, and I push the button for them."
Well this really bothered me, so I decided to trap the students in a logical discussion. I had been brought up in a Jewish home, so I knew the kind of nitpicking logic to use, and I thought "Here's fun!"
My plan went like this: I'd start off by asking, "Is the Jewish viewpoint a viewpoint that any man can have? Because if it is not, then it's certainly not something that is truly valuable for humanity... yak, yak, yak." And then they would have to say, "Yes, the Jewish viewpoint is good for any man."
Then I would steer them around a little more by asking, "Is it ethical for a man to hire another man to do something which is unethical for him to do? Would you hire a man to rob for you, for instance?" And I keep working them into the channel, very slowly, and very carefully, until I've got them - trapped!
And do you know what happened? They're rabbinical students, right? They were ten times better than I was! AS son as they saw I could put them in a hole, they went twist, turn, twist - I can't remember how - and they were free! I thought I had come up with an original idea - phooey! It had been discussed in the Talmud for ages! So they cleaned me up just as easy as pie - they got right out.
...
Something else happened at that time which is worth mentioning here. One of the questions the rabbinical students and I discussed at some length was why it is that in academic things, such as theoretical physics, there is a higher proportion of Jewish kids than their proportion in the general population. They rabbinical students thought the reason was that the Jews have a history of respecting learning: They respect their rabbis, who are really teachers, and they respect education. The Jews pass on this tradition in their families all the time, so that if a boy is a good student, it's as good as, if not better than, being a good football player.
It was the same afternoon that I was reminded how true it is. I was invited to one of the rabbinical students' home, and he introduced me to his mother, who had just come back from Washington, D.C. She clapped her hands together, in ecstasy, and said, "Oh! My day is complete. Today I met a general, and a professor!"
I realized that there are not many people who think it's just as important, and just as nice, to meet a professor as to meet a general. So I guess there's something in what they said.

Ce récit soulève la question de l'utilisation des ascenseurs pendant Chabbat. Comme de nombreux sujets dans le judaïsme, c'est une problématique qui apparait toute simple mais qui en profondeur est assez complexe.

Durant Chabbat (en gros du vendredi soir au samedi soir), jour qui correspond au repos de Dieu après avoir créé le monde, les juifs ont 39 interdictions à respecter. Ces 39 interdictions se rapportent aux 39 travaux nécessaires à la construction du Temple. L'une d'elle, l'interdiction d'allumer un feu, a été modernisée en : interdiction de modifier la tension électrique d'un appareil. Ainsi il est interdit d'allumer ou d'éteindre la lumière durant Chabbat.

Passons les problèmes inhérents aux appareils électroménagers du type réfrigérateur ou four électrique, et intéressons-nous aux ascenseurs.

Il parait assez clair que l'utilisation normale d'un ascenseur transgresse un interdit de Chabbat, puisque le fait d'appuyer sur le bouton de l'étage de destination actionne le moteur de l'ascenseur.

On peut poser alors la question : oui mais si c'est un goy qui appuie sur le bouton ?

Les réponses usuelles sont alors :

Si le goy appuie sur le bouton de son étage, c'est ok, car il fait l'action pour lui-même, en revanche s'il appuie sur le bouton de l'étage du juif (comme dans le récit de Feynman) ce n'est pas ok car le juif profite directement de cette action.

Bien sûr, ce n'est pas si simple, car pour des questions de sécurité la plupart des ascenseurs modernes sont équipés d'un faisceau infrarouge au niveau de l'entrée, dont la coupure entraîne la réouverture des portes, afin d'empêcher que les portes se refement sur quelqu'un en train d'entrer ou de sortir.

Mais même, en admettant que l'ascenseur n'ait pas de faisceau infrarouge ou que l'on puisse sortir assez rapidement sans l'actionner, est également soulevé un problème d'apparence, car que va penser un juif en voyant un autre juif prendre l'ascenseur pendant Chabbat ? Il suffit de l'informer, répondra-t-on.

Évidemment, en creusant un peu, d'autres questions surgissent, et c'est là que le sujet devient scientifique. L'ajout d'une personne juive dans l'ascenseur ne provoque-t-elle pas un poids supplémentaire dans la cabine, donc une augmentation de la puissance du moteur lors de l'utilisation, voire la création d'étincelles ? Oui, pour les ascenseurs standards, disent de nombreux rabbins. Plus précisément, un ascenseur standard pourrait entre autres :

  • déclencher le mécanisme de ralentissement avant l'arrivée du fait du poids des personnes à bord
  • déclencher la lumière intérieure de l'étage en cours du fait de la présence des occupants
  • déclencher l'ouverture des portes, comme mentionné précédemment

De fait certaines autorités religieuses, comme le rabbin lithuanien Yossef Chalom Elyachiv, ont complètement prohibé l'utilisation d'ascenseurs durant Chabbat.

D'un autre côté, des esprits créatifs ont conçu l'ascenseur de Chabbat. Un ascenseur spécial, qui, en mode Chabbat, fonctionne toujours à pleine puissance, s'arrête automatiquement à tous les étages, bref évite tous les problèmes sus-cités. Des brevets ont même été déposés.

L'Institut Tsomet dirigé par le Rabbin Yisrael Rosen a étudié le problème plus en détails (on atteint déjà une bonne dizaine de pages) pour arriver à toutes les conditions que doit satisfaire un ascenseur pour que ses utilisateurs chabbatiques ne transgressent aucune interdiction.

En conclusion, deux juifs, trois avis !

Note : la motivation initiale de cet article était de savoir si un paternoster[2] pouvait faire office d'ascenseur de Chabbat.

Un paternoster

Notes

[1] Interjection à laquelle selon la légende Richard Feynman aurait répondu : No I'm not joking. And don't call me Shirley.

[2] Le site 99% invisible (99pi pour les intimes) est une mine d'or pour les amateurs d'architecture urbaine. Voir par exemple cet article sur les Ampelmännchen (signaux lumineux pour le passage des piétons aux feux rouges) de différentes villes du monde.