Launch of the Alexander Friedmann Fund
100 years ago, we thought we lived in a finite, static universe. This was without counting on the work of a brilliant physicist who published in 1922 the first founding article of modern cosmology: Alexander Friedmann.
Before the Russian scientist, cosmological solutions to the very complex equations of general relativity had been found, by Albert Einstein himself and by Willem de Sitter. However, these solutions described static universes, in accordance with the beliefs of the time. Friedman, in a scientific paper published in 1922, was the first to conceive and identify solutions describing a non-static universe: an “expanding” space, according to the expression he invented, despite the reticence of his peers to consider this possibility.
Two years later, Friedmann reiterates: he publishes another paper in which he questions the dominant conception until then of a finite universe, by finding solutions describing a universe of infinite volume.
The concepts developed in these two papers were relatively ignored initially, Einstein still describing in 1927 as “abominable” the idea of an expanding universe. However, as observations in this direction accumulated, the scientific community gradually accepted Friedmann's revolutionary ideas, which were also developed by George Lemaître a few years later. These concepts and equations still form the conceptual basis of cosmology, which has now become a science of precision.
Today, scientists study not only the Universe in its totality, but also on a smaller scale. In particular, black holes, these ultra-compact objects from which nothing, even light, can escape, are sources of general relativity effects that can now be observed.
In order to celebrate Friedmann seminal paper centenary, École Polytechnique and its Foundation, thanks to the support of Romain Zaleski, have decided to launch the Alexander Friedmann Fund to initiate various scientific activities: covering the wide range of subjects associated with the field of cosmology, from the study of the primordial universe to the modified theories of gravitation.
Among these activities, the Friedmann Colloquium is a general seminar addressing an audience of scientists and science students. To inaugurate these conferences, Frank Eisenhauer from Max Planck Institute for Extraterrestrial Physics (Germany) came at l’X to talk students and researchers about “The galactic center black hole, the effects of general relativity, and how to observe them”. As a specialist in spectroscopy and interferometry, Frank Eisenhauer has been in charge of two major instruments that have changed the way the sky is observed. SINFONI and GRAVITY, instruments installed on the European VLT telescopes in Chile, allowed the characterization of the center of our galaxy, the Milky Way, and the measurement of the orbit of stars and effects predicted by the theory of general relativity such as the Einstein shift and the Schwarzschild precession. This led to the confirmation of the presence of a supermassive black hole of about four million times the mass of the Sun. The talk told the story of these discoveries, up to the recent black hole silhouettes observed by the Event Horizon Telescope.
The launch of Alexander Friedmann Fund was also the occasion to open an exhibition at the school library: “Regards sur Friedmann”.