Release date is 2026-03-07

La Science avant Einstein -- La doctrine de la Relativité -- Les conséquences de la Relativité -- Espace et Matière -- L'Univers est-il infini? -- L'Espace à quatre dimensions et les Géométries non-euclidiennes -- L'Espace-Temps de Minkowski. La Relativité généralisée -- Sur quelques résultats de la Relativité -- Qu'est-ce que le Temps? -- Conclusion.

Laurent Vogel and the Online Distributed Proofreading Team at https://www.pgdp.net (This book was produced from images made available by the HathiTrust Digital Library and the Internet Archive.)

"Pour comprendre Einstein" by Théophile Moreux is a popular science treatise written in the early 20th century. It sets out to explain Einstein’s relativity to non-specialists by placing it in the broader trajectory of modern physics, correcting sensational claims, and weighing Einstein’s role against earlier discoveries.

The opening of the treatise explains why relativity suddenly captivated the public and argues that a clear view requires revisiting the prior half‑century of physics. Moreux surveys the emerging picture of the atom (nuclei and electrons, radioactivity, transmutation), the velocity‑dependence and electromagnetic nature of mass, and the radiation pressure of light, linking these to astronomical phenomena like comet tails. He reviews the emission versus wave views of light, the contested ether, and the null Michelson–Morley experiments, then shows how Lorentz’s contraction arose before relativity. Turning to Einstein’s approach, he frames the key postulate of constant light speed and builds a careful, convention‑based notion of simultaneity using light signals, distinguishing objective events from their subjective observation. He dissects popular paradoxes (such as high‑speed travel and “time slowing”) as artifacts of signal delay and clock‑setting conventions, and closes by noting that scientific hypotheses are tools that connect facts and can predict new ones, even if they are provisional. (This is an automatically generated summary.)

Originally published: Paris: Gaston Doin, 1922