About dark matter and gravitation Alain Haraux To cite this version: Alain Haraux. About dark matter and gravitation. 2020. hal-02883031 HAL Id: hal-02883031 https://hal.archives-ouvertes.fr/hal-02883031 Preprint submitted on 28 Jun 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. About dark matter and gravitation. Alain Haraux Sorbonne Universit´e,Universit´eParis-Diderot SPC, CNRS, INRIA, Laboratoire Jacques-Louis Lions, LJLL, F-75005, Paris, France. e-mail:
[email protected] Abstract A close inspection of Zwicky's seminal papers on the dynamics of galaxy clusters reveals that the discrepancy discovered between the dynamical mass and the luminous mass of clusters has been widely overestimated in 1933 as a consequence of several factors, among which the excessive value of the Hubble constant H0, then believed to be about seven times higher than today's average estimate. Taking account, in addition, of our present knowledge of classical dark matter inside galaxies, the contradiction can be reduced by a large factor. To explain the rather small remaining discrepancy of the order of 5, instead of appealing to a hypothetic exotic dark matter, the possibility of a inhomogeneous gravity is suggested.