Philippe Brax is a theoretical physicist working at the Institute of Theoretical Physics of the University of Paris-Saclay, France. He is a specialist of cosmology and possible modifications to general relativity. After obtaining a Ph.D. in high-energy physics from the University of Paris 6, and two postdoctoral positions at the University of Cambridge, UK, and at CERN, Geneva, he began specializing in theoretical cosmology. He is the author of more than 200 papers published in peer-reviewed journals. When not working, he is most likely found reading about history, walking up and down the hills of Provence, running marathons, or playing tennis with his family.