I was born on 7 March 1947 in Chalon-sur-Saône, Burgundy. My parents worked in the city hospital ― Mother as a midwife and Father as an X-ray technician. My father was a self-taught man who had received only primary school education. My younger brother and I went to a technical high school and during this early period, inspired by the encyclopaedia my father bought, I became very interested in science and astronomy.
Later, I was admitted to “Lycée du Parc” in Lyon to prepare for the competitive examinations for admission to the selective schools of French universities. At that time, my idea was to become an engineer. It was only when I had to choose between the schools I had gained admittance to, that a friend and I discussed our futures and decided that we wanted to try to go into scientific research; we chose to go to “Ecole Normale supérieure, Cachan”. I followed Physics studies at “Université Paris Sud” in Orsay and gained a master in theoretical physics.
In 1969, I attended a seminar by Roland Omnés on a model of the universe he had developed in which the symmetry between matter and antimatter was preserved, a topic I found fascinating, and I was successful in obtaining a master internship under him and Evry Schatzman (my future thesis adviser). The problem they gave me was to compute the annihilation rate between a matter and an antimatter plasma filling two half space. Evry Schatzman took me as a graduate student to keep working on the baryon symmetric model at CERN during his sabbatical year there – a chance I only measured later!
This was followed by two years, 1970–1972, at Goddard Space Flight Center (GSFC) with a fellowship of the European Space Research Organisation (ESRO), ancestor of the European Space Agency. NASA had built the first gamma ray satellite aimed at mapping the whole sky and I worked with Floyd Stecker trying to find evidence of annihilation in the form of a cosmic gamma-ray background. The galactic gamma ray emission was very dominant and we did high-energy galactic astrophysics in parallel to searching for the cosmic gamma ray background. On my return to Paris, I was asked by the Fundamental Physics Panel of ESRO to write a report on what space observations could bring to the study of Cosmic Background radiations. This led me to learn the potential power of detailed observations of the microwave background discovered eight years before by Penzias and Wilson, and, in the seminal paper of Partridge and Peebles, the potential of detecting the Cosmic optical and infrared backgrounds containing the radiation coming from all generations of galaxies.
I went back to GSFC for a postdoctoral year (1974–1975). During that time Floyd Stecker, Giovanni Fazio and I did predictions of the Cosmic Infrared Background for the problem of propagation of ultra high-energy cosmic rays through cosmological distances.
About the same time, with Charles Ryter and Guy Serra, we started investigating what fraction of starlight in galaxies is absorbed by interstellar dust and converted to far infrared. This was for me the start of involvement in conceiving instruments. We built a balloon borne experiment to measure the diffuse galactic far infrared emission. The IRAS satellite showed later, surprisingly, that 15% of the energy was reradiated in the mid infrared (6 to 60 micron). This has led to the discovery of a new key ingredient of the interstellar medium: Polycyclic Aromatic hydrocarbon molecules.
In 1978 I met Catherine Maussion, now my wife, who was a journalist on a major daily French newspaper (Liberation) and during these 40 years we both have maintained our professional activities. We have two sons, and now three grandchildren.
From 1978 to 1982 I was deputy director of “Institut d’Astrophysique de Paris” (IAP). I then joined the astrophysics team within the Physics department of “Ecole Normale Supérieure”.
In 1990, I led the creation of the “Institut d’Astrophysique Spatiale” (IAS) in Orsay, which has taken a major role in many Space experiments over the last 30 years. I was director of IAS from 1997 to 2005.
By 1980, the main directions of my future research were set: space observations offer a unique window on the infrared-to-submillimeter spectral range. Observations with high sensitivity and resolution of the Cosmic microwave background and of dust emission from mid infrared to millimeter wavelengths in our Galaxy and from all galaxies, would lead to major advances in astrophysics and cosmology.
In 1993, in response to a call from ESA, I proposed, with a large international team, an instrument concept that was to become the High Frequency Instrument on the Planck mission.
This mission became, after COBE and WMAP, the third generation CMB mission. Its sensitivity, very broad frequency range, 5 arc minutes resolution and polarization capabilities, allowed it to confirm several generic predictions of an inflation phase in the very early universe. Although I know that this is what modern cosmology is about, I am still amazed that this can really be done. Looking back, this was made possible by these 50 years of incredible progress in cosmology but also in technology, and the work of a very large number of people.
26 September 2018 Hong Kong
