The legacy of Pierre-Gilles de Gennes

A scientific symposium on the legacy of Pierre-Gilles de Gennes will be held in Paris on 23 and 24 November. Nobel Prize in Physics in 1991, director of the ESPCI Paris - PSL for almost 25 years, he was a versatile and passionate scientist who was also very involved in science education, especially for high school students. For the occasion, Claire Wyart, his daughter and Inserm researcher at the Institut du Cerveau (ICM), and Jean-François Joanny, who was his thesis student and later director of the school, look back at this unique character.

What was Pierre-Gilles de Gennes’ approach and vision of science?

Claire WyartCW: Above all, he was very curious, and had an ability to absorb complex knowledge that would seem like a jungle to anyone else. From this he was able to establish laws of scale, as in his work on polymers and cross-linking. This was a key aspect for him: to focus on the essential cause that governs a phenomenon.

JFJ: His very broad view of problems that cut across disciplines was indeed exceptional. Interdisciplinarity was a key factor: tackling a problem like polymers with the weapons of physics and chemistry created a new field of study at the time, called “soft matter”.

A symposium on his legacy, what does that inspire you?

CW: It’s been 30 years since he won the Nobel Prize, and soon 15 since he left us. He was passionate about many of the issues facing society today, from social crisis to public education in science, a key issue today as the pandemic illustrates. His voice of discernment and common sense through the laws of scale is missing in today’s debates.

JFJ: Without necessarily being aware of it, young scientists are working on issues that have been highlighted by PGG. Being able to discuss all this research, in physics, chemistry or biology, is a way of putting forward one’s vision of science. It is also an opportunity to recall an important principle: complicated things can be explained simply, without making misleading short cuts.

What was his connection to teaching?

CW: He had a great desire to pass on information, especially to young people. He put everyone on an equal footing when he talked. He spent a lot of time giving lectures in high schools, and I was surprised to meet people later on in my life who told me that they had chosen physics after one of his lectures, even though they had never been destined to do science in the first place.

Jean-François JoannyJFJ: For example, he made major changes at the ESPCI that were very lasting. The school was modernised in its teaching and owes him a lot today. I am thinking in particular of the introduction of tutorials, the strengthening of links between research and education, the introduction of biology, and courses given by external speakers...

CW: This notion of openness is crucial: open-mindedness, social openness, openness to the world. The ESPCI was close to his heart and he put a lot of intention and will into changing things.

What image do you keep of the scientist, but also of the man?

JFJ: He was a brilliant and very cultured man. I have wonderful memories of the discussions we had together, about sciences and other subjects. I remember him being the first person to tell me about the Harry Potter books, which he thought were great at the time!

CW: He loved to play ’idea ping pong’, sharpening his mind to ask the right questions. As I grew up, I realised that I had received a precious gift from my parents through this infinite love of learning and making sense of the world around us, a bit like the love that a craftsman passes on to his children through passion (editor’s note: Claire Wyart’s mother, Françoise Brochard-Wyart, is also a renowned soft matter physicist).
What I remember most of all is his enthusiasm and his altruism: France has built incredible intellectual edifices of which we are all heirs. Today we are incredibly lucky to live in this country and to be able to share, exchange and serve the whole community as researchers.