Langevin invites a change in the focus of historians of relativityRelativityhistory of, from the genesis of the theory and priority issues to the multiple ways of exploring and interpreting it. For Langevin, Einstein’sEinstein, Albertmass and energy paper on the inertia of energyInertia of energy confirmed his own results and increased the strength of the principle of relativityRelativityPrinciple of. Langevin did not conclude that the etherEther was unnecessary, only that it could not be detected, so there was no incompatibility between relativity and electromagnetismElectromagnetism using the ether. Langevin was among the first scientists to promote the theory of relativity in France as he understood that Einstein’s principle shocked the foundations of physics, and that the shock resonated beyond its boundaries. In an effort to reconceptualize space and time, he presented two lectures on this new physics to a philosophical audience, in 1911. To exemplify the break between the common view of time and the notion of time in relativity physics he emphasized the time shift between a space traveller and a stationary one. Langevin’s personal contribution in the history of relativity was to develop a conceptual view of the principle of relativity that interpreted Einstein’s conclusions in philosophical terms.