Christian Bracco is Associate Professor at theUniversité Côte d’Azur and a research scientist in theAstronomical sciences team at the Paris Observatory.Trained as a physicist, he is a recognised specialist inthe history of physics of the nineteen and early twentiethcenturies in optics, electromagnetism and relativity.He lectures on the history of physics to undergraduateand graduate students in philosophy, to future physicsteachers and in physics-intensive doctoral schools.