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Jury Prof. Yves CAUDANO (UNamur), chairmanProf. André FÜZFA (UNamur), secretaryProf. Dominique LAMBERT (UNamur)Dr. Jérémy REKIER (Observatoire royal de Belgique et UCLouvain)Prof. Dr. Félix FINSTER (Regensburg University) Summary Sounding the Universe with a relativistic solar sailboat or Einstein-Dirac fermionsThe Universe exerts a curiosity on man that is both undeniable and fundamental. To unravel the mysteries of the Cosmos, man is driven to develop two major investigative strategies: direct exploration by sending space probes, and indirect exploration by observing cosmic electromagnetic fields, gravitational waves or particles such as fermions.Following these two strategies, in this thesis we develop, in the first approach (consisting of sending a space probe), a relativistic kinematic and dynamical model of photonic sails (light sails) with arbitrary reflectivity and absorbance, moving in a non-rectilinear manner with the aim of exploring interstellar space. The problem is to determine the sail's trajectory in a Minkowski spacetime, a four-dimensional variety. From detailed calculations, we obtain the sail's universe line in the laser reference frame as a function of the sail's proper time.The second approach applies the Two-State Vector Formalism and weak measurements to a homogeneous, isotropic cosmological framework. By coupling Dirac spinners to classical gravity, we calculate weak values of the energy-impulse tensor, the Z component of spin and pure states. Extending the work of Finster and Hainzl on Einstein-Dirac cosmology, we show that the accelerated expansion of the Universe can be interpreted as a consequence of post-selection. We also demonstrate that weak measurements can amplify signals using simpler equipment, thanks to judicious selection of the initial and final state vectors. In addition, this procedure highlights certain geometric properties of the Cosmos' three-dimensional space, offering a new way of exploring the structure of the Universe.We also examine the mathematical structure on which the Dirac equation rests beyond the usual dimension and signature. This reveals a rich internal symmetry and gives rise to a particularly aesthetic diagrammatic representation. Abstract Probing the Universe with a Relativistic Light Sail or Einstein-Dirac FermionsHumanity's profound curiosity about the cosmos is both undeniable and fundamental. To demystify the Universe, humankind is compelled to develop both direct and indirect probing strategies: direct exploration through physical visits using probes, and indirect exploration by observing cosmic electromagnetic field, gravitational waves and particles such as fermions.Building on these two strategies, this thesis proposes two distinct approaches to probing the Universe. In the first approach, we present a relativistic kinematic and dynamic model of light sails with arbitrary reflectivity and absorptance, undergoing non-rectilinear motion as a method of interstellar exploration. The problem involves solving for the trajectory of the sail in a 4-dimensional Minkowski spacetime manifold. By detailed computation, we derive the worldline of the sail in the laser's frame in the sail's proper time.The second approach applies the Two-State Vector Formalism and weak measurements to a spatially homogeneous and isotropic cosmological framework. Coupling Dirac spinors with classical gravity, we compute weak values of the energy-momentum tensor, the Z-component of spin, and pure states. Extending the work of Finster and Hainzl on Einstein-Dirac cosmology, we demonstrate that the Universe's accelerated expansion can be interpreted as a consequence of post-selection. We also show that weak measurements can amplify signals with simpler equipment by carefully selecting initial and final state vectors. This process also reveals geometric properties of the spacelike three-manifold of the Cosmos, opening new way on probing the structure of the Universe.We explore also the mathematical framework underlying the Dirac equation beyond the standard dimension and signature. This enterprise reveals its symmetrically rich properties and aesthetic diagrammatic representation.

Since the discovery of fire in prehistoric times, humans have been fascinated by matter, its properties, and the changes that occur naturally or as a result of human intervention. Now known as "chemists," specialists in the reactivity of matter continue to pursue the art of experimentation and discovery. The products of their essential knowledge are applied in the fields of nutrition, health, hygiene, transportation, sports, construction, and environmental protection. 

Professor Eli Thoré and Justine Bélik have just been honoured by the Adrien Bauchau Fund (FAB). Created in memory of the founder of the Biology Department at UNamur, the FAB has been promoting excellence in education and research in the life sciences since 1989.

An unusual piece of research recently mobilized teams from UNamur's Biology Department. Genetic analyses carried out by the Environmental and Evolutionary Biology Research Unit (URBE) were able to confirm the protected status of a herd of wild mouflons based in Gesves, and thus highlight the importance of saving them.

In May 2025, the Department of Physics welcomed two special visitors: Serge Mathot and François Briard from Namur, both alumni of UNamur and members of CERN. Several activities were on the program, ranging from a visit to the particle accelerator, to science popularization and thematic seminars, particularly in heritage sciences. The aim? To identify areas or activities in which UNamur and CERN could strengthen their collaboration.

A master's student in physics at the University of Namur, Kevin Persoons is not only passionate about science, he also embodies student and cultural engagement! At 24, he already has several years of involvement in university life under his belt, notably within the General Student Assembly (AGE), where he has served as administrator, cultural delegate, and then president. Today, as a youth representative, he is preparing to promote Namur on the European stage.

Beautiful victory for Margaux Mignolet, a researcher at the Faculty of Medicine's Unité de Recherche en Physiologie Moléculaire (URPhyM), who wins 1st prize in the Belgian inter-university final of the Ma thèse en 180 secondes (MT180) competition. Her research? To better understand the mechanisms of antibodies active in cases of long COVID. The second prize in this national competition was also won by a candidate from Namur. It was Petra Manja, from the Unité de Recherche en biologie des micro-organismes (URBM), Department of Biology, Faculty of Science, and is pursuing a thesis aimed at understanding resistance mechanisms in the bacterium E. coli. Both are also researchers at the NARILIS Institute.

For several years now, researchers have been striving to make their laboratories "greener". A series of actions have been implemented, funded by the CaNDLE 2023 call for projects have been supported by the Department of Biology at the initiative of Alison Forrester and Frédéric Silvestre, the project leaders, as well as by Campus Infrastructure Management Services (SIGeC) and Prevention Services (SerP). In March 2025, a Green Day was held to provide information on the project's progress, and to motivate people to join the initiative.  

A practical training course in computational quantum chemistry was organized from May 26 to 30, 2025 as part of an ERASMUS+ collaboration between the University of Sfax and the University of Namur. This inter-university training course for PhD students in chemistry and physics from the Tunisian University brought together more than 20 students.

High-Sensitivity Birefringence Mapping Using Near-Circularly Polarized Light I will describe several techniques for mapping a two-dimensional birefringence distribution, which can be classified according to the optical schemes and principles of work:Illumination geometry (transmitted light/reflected light)Image acquisition (sequential acquisition/simultaneous acquisition)Polarization control (electrically controlled variable retardance/mechanical rotation).This classification facilitates a comparative analysis of the capabilities and limitations in these methods for birefringence characterization. Polychromatic polarizing microscopy (PPM) provides unique capabilities to alternative methods. It leverages vector interference to generate vivid, full-spectrum colors at extremely low retardances, down to < 10 nm. PPM is a significant departure from conventional polarizing microscopes that rely on Newton interference, which requires retardances above 400 nm for color formation. Furthermore, PPM's color output directly reflects the orientation of the birefringent material, a feature absent in conventional microscopy where color is solely determined by retardance.Joint seminar of ILEE & NISM!The seminar is open to external people too, no need to register. More info