Bernard Guy is a French scientist and Emeritus Professor from Mines Saint-Etienne, Institut Mines Télécom. A graduate of the École des Mines (Paris, 1971), he holds multiple doctoral degrees: Docteur ingénieur, Ingénieur géologue, and a Doctorate ès sciences from Université Paris 6. Throughout his career, Dr. Guy contributed to research and teaching in a wide range of scientific disciplines, including geology, geochemistry, thermodynamics, physics, mathematical modeling and the philosophy of science. He has actively participated in academic societies such as the Société Française de Physique, the Comité Français d’Histoire de la Géologie and the Société des Amis d’André Marie Ampère. A thinker with a multidisciplinary outlook, he also contributes to discussions on the foundations of physics and space-time theories. His commitment to scientific inquiry continues through his role on the steering committee of the Joint European Thermodynamics Conference (JETC). He was awarded the Arthur Iberall Gold Medal (2020) at the Thermodynamics 2.0 International Conference (USA) for contributions to the understanding of space, time, and motion in physics. He has supervised nearly thirty doctoral dissertations, written some two hundred scientific articles in peer-reviewed journals, and authored a dozen books. His category of research is best described as interdisciplinary physical sciences with an emphasis on thermodynamics and epistemology.

Space and time are constructed together. Implications for the quantum/classical distinction and for various problems in cosmology. Remarks on inflation We propose a fundamental rethinking of the concepts of space and time. Although relativity links them through measurement, they are still treated as two independent entities, each defined by its own properties. We instead advocate a relational approach in which space and time are constructed together through the comparison of motions. Motion is regarded as the primary concept, rooted in embodied experience rather than in abstract definitions. This perspective, inspired in part by phenomenology, leads to a reassessment of relativity and seeks to bridge the gap between the physical sciences and the humanities in their understanding of time. Two major consequences follow from this reinterpretation. First, a form of indeterminacy emerges already within classical physics, leading to relations analogous to Heisenberg’s uncertainty principle. Features usually considered specific to quantum mechanics—such as probabilistic descriptions, limitations on strict causality, superposition, and entanglement-like correlations—may therefore have classical counterparts. Second, the speed of light should not be regarded as an absolute quantity taken in isolation. Only ratios such as (v/c) have physical meaning. The paper argues that the effective speed of light on cosmological scales may be lower than its locally measured value because of a gravitational optical index of about 2.4. This result is obtained from a new metric, denoted (G), constructed by summing weak-field Schwarzschild metrics over the observable Universe and accounting for matter inhomogeneities. The proposed framework offers an alternative explanation for several cosmological puzzles without invoking dark matter or dark energy, while providing a quantitative realization of Mach’s principle and identifying it with the observed criticality (flatness) of the Universe. Finally, these ideas are applied to cosmic inflation. The flatness of the Universe is interpreted as a natural consequence of Mach’s principle rather than of finely tuned initial conditions. Likewise, the tiny anisotropies observed in the cosmic microwave background, usually attributed to quantum fluctuations, may also arise from fluctuations within classical physics. Inflation thus becomes less indispensable and can be reconsidered within a unified relational framework of space, time, and motion.