Témoignages

Dear Bob Coecke,

By the way I am one of Piron’s Ph.D. student. Maybe the last official one and certainly battling Terje Aaberge for the qualification of most obscure. I wrote a few lines to Diederick Aerts to tell him the mixed feelings I had towards Piron. I paste them below. Prior to that I remember a « Pironnerie » that you may find funny:

In June 1986 there was to be a conference entitled: « Geometry and Physics » in Paris and the Saturday before that the « Séminaire Bourbaki » was taking place. Piron told me to attend both. I did that for the first lecture of the Bourbaki and then left as I could not get really what they were talking about. I met Piron in the corridor who was joking with the secretaries. We went for a drink in a café nearby and came back to the Bourbaki’s lectures which were in recess. Piron told me: « why don’t we seat there in the first row ». I was reluctant but then I obliged (or obeyed). These were the kind of old school benches and desks where when seated the guy in the middle is trapped if others on his side don’t leave beforehand, unless he manages to scramble underneath the desk; not very discreet to say the least. When the crowd had gathered back and I was then a prisoner, Piron whispered to my ear: « usually the first row is reserved to people who belongs to the Bourbaki committee ». Boy! There I was in the first row not understanding a word from what the speaker was telling, my screw Piron next to me, probably grasping at the most one or two more, but delighted by his teasing of the establishment. Typical Piron.

Best,
Benoit Boulat

Dear Professor Aerts,

This weekend I went to Switzerland for a family reunion and I was traveling by train from Geneva airport to Montreux. I was reminded of my days when I was doing my Ph.D. in Geneva under the direction of Constantin Piron. At that time I was living in Lausanne, commuting daily. Whenever I was taking a regional train stopping at intermediate stations I was half hoping, half dreading that Piron would show up since he was also commuting, but from one of these intermediate station between Lausanne and Geneva. A mixture of fear and hope depicts well my relationship with Piron. Coming from a family that had very little scientific tradition I was not ready to defend my point of view in front of Piron; I must add that, as viewed from today, I don’t think Piron was ready to guide me in defending my point of view. Perhaps you were for something in that situation, since Piron mentioned several times to me, « that when someone shows that what you have done is not correct, c’est dur, c’est très dur ». He was referring to yours showing that some of his « axioms » for quantum mechanics were not valid for composite system.

In any case I remember that the first time I met Piron, I told him something like: « of course experimentalists are sometimes successful at verifying theories, because they do everything possible in order to do so. » I thought Piron got interested by that remark but he never engaged in discussing it again after he decided to take me as a Ph.D. student. Instead the subject of my thesis ended up to develop a mathematical formalism that would allow to describe a physical system without precluding of its classical or quantum nature. This was done using some version of the deformation theory of algebraic structures, an approach advocated then by Moshe Flato, André Lichnerowitch and coworkers and Piron was mingling with that crowd during that period. Was it too early after the completion of your Ph.D. thesis and he wanted to stay away from too foundational questions that were risking to damage further his own constructions? Maybe so. Had I had a stronger scientific character I would have insisted on developing something around my remark above. Had Piron been a better master he would have helped me to do so.

In my opinion you are the most successful of Piron’s student, in the sense that the pupil has surpassed the master in a way that has enlarged and developed the master’s point of view. Gisin has certainly been successful, but certainly more for the experiments he directed than the theories he proposed. Others I don’t know them well. In the nineties Piron apparently went again through a new creative period when he interacted with the Moore, Coecke, … (as viewed from 2019, Coecke has become very successful, probably surpassing his mentor Aerts)

Piron and I were not really meant to work together I suppose. Yet I learned a lot from him and although my attraction to quantum physics predated my encounter with him, after I gained access to some of his thinking, the work of his student (you) and the considerable amount of work that has been done on and around this subject, I have lived in a world in which to this day I keep a lot of interest into. I am indebted tremendously to Piron for this and certainly for some time, I considered him to be my master. I was always embarrassed however by the way he was defending his point of view. I was never able to understand how one could be so squarish and bullish in doing so. There were notions in the Piron(-Aerts) approach of QM that I could not fathom like saying (I believe this is mentioned in your lecture at the AVCP course on QM in the Valais, in the Swiss alps, and I am quoting from bad memory): « we do not have to justify why we consider this particular system that is defined by the type of questions we ask about it. » Then of course you can claim that you are a « realist », since you have evacuated all the linguistic apparatus which has helped you to circumscribe the system you want to study. Once again I did not pursue my own penchant, attraction or point of view but much later, reading the (later) Wittgenstein helped me gaining a better understanding about this problematic.

If one were sensitive, life with Piron was not always agreeable. Like when I said finally « tu » to him after he insisted for several years that I do so and from that point on he started to say « vous » to me. Or like after the successful completion of my Ph.D. I asked for a letter of reference from him; handing it to me he said (getting back to « tu », then): »tu comprends, je ne peux pas en écrire une trop bonne, car sinon les gens vont me demander: ‘pourquoi tu ne le gardes pas?’ . »

The third anecdote I want to convey describes well the mixed feeling I had towards Piron. The feeling that even if he was performing apparently badly, I would try to take the opportunity to grow from it. Piron was giving a course he entitled: « axiomatique quantique » (he claimed later he never gave such a course saying: « pourquoi tu parles comme Gisin? ») and a retired person was following it. After the lectures we usually went to the cafeteria for a drink and once the retiree asked a question and said looking at me: « Monsieur qu’est-ce que vous en pensez? » I could not even open the mouth that Piron had said: « il ne pense pas ». I was so baffled that I kept silent. I thought I could say: « je ne suis pas Cartésien, ce n’est donc pas grave » but this was more a sophism that something I was really feeling. This interjection by Piron was written in me like with hot iron though. About a decade later as I was at Stanford Unversity for an interview, I was strolling through the Rodin garden. I caught view of the « gates of hell » and realized who was sitting right at the top of them, contemplating them? None but the famous « thinker » by the famous sculptor!
http://www.musee-rodin.fr/fr/collections/sculptures/la-porte-de-lenfer . There was the illumination! There was my answer to Piron! I contacted Piron again to ask him to write a letter of reference on my behalf for the Stanford position (!! I did not get the position ) but mostly to tell him about my revelation. And there was Piron telling something like: « c’est dommage que tu n’en ai pas parlé plus tot, … » and citing some reference about « le maître » by his favorite philosopher « Thomas d’Aquin » as if he had done that to educate me.

From then on we had a quieter correspondence for a while. He sent me his latest papers and I asked him a few more question about the Gödel theorem for which I was interested in. We deviated to the Prologue to the Gospel of John and the sentence where it is said: « in the beginning was the Word, and the Word was with God and the Word was God »; I told Piron that this situation was « in the Beginning » and that this should be our goal for the Word in the End. Until then we had to live with an imperfect Word to express and describe things. This form of « The Word was God » Piron began to explain was the result of a bad translation; that in reality one should say « … and God was the Word » . I understood then the misunderstanding there was between Piron and myself and I told him he was wrong. The pupil had finally realized he had to trace his own path. We never exchanged any e-mails any more.

In the office of Stuckelberg he moved into when I was a Ph.D. student after the latter died, there was a reproduction of M.C. Escher’s Belvedere, (http://www.wikipaintings.org/en/m-c-escher/belvedere) Piron had placed or kept on one of the wall which acted on me as a parabola. Piron was the man with the feathered beret on the first floor of the building, looking away peacefully to the mountainous landscape. Although it was not the best vantage point in the building it was the place that offered the most freedom. Away from the fight to get to the top floor where a lady was waiting but where one risked to loose one’s purpose either in the fight or the courtship. Away from the jails in the basement where there was no freedom of thinking and away from the bench where the lazies were sitting but where no inspiring views were available. And away from the base of the stair case where learning started and one was not sure yet whether truth or seduction was our mentor.

Sincerely,

Benoit Boulat