Under the title "Crossover of quasi-localized dynamics and diffusion in supercooled liquids," a study conducted at the European Synchrotron Radiation Facility (ESRF) in Grenoble by researchers from the Universities of Brussels, Padua, Pisa, and the ESRF has rewritten the molecular dynamics of liquids toward the glassy state. The study was published in Nature Physics. The paper demonstrates that the "dance of molecules" is not made up of isolated movements, but of a single, cohesive mechanism. What distinguishes a flowing liquid from a solid and brittle glass? At first appearance, the solution appears simple: in the former, atoms move freely, but in the latter, they remain fixed. However, for material physicists, the so-called "glass transition" is one of nature's most puzzling mysteries. When a liquid cools to the glassy state, the time it takes for molecules to rearrange increases exponentially, yet their atomic structure remains nearly unchanged. How does a system become rigid without changing the sequence of its components? A superposition of distinct motions has been the interpretation of this phenomenon by physics for decades. On a long timescale, structural relaxation is the primary process by which molecules ultimately escape from the "molecular cages" formed by their neighbors, thereby enabling the liquid to flow. At the other extreme, at short timescales, are the atoms' frantic vibrations within the same cages. Between these two extremes is the mysterious Johari-Goldstein relaxation, discovered in the 1970s. For fifty years, the debate has been whether this is an autonomous and local motion or if it is related to the liquid's primary dance. This worldwide research team is currently investigating this physics riddle using the ESRF and a cutting-edge technology known as X-ray time-domain interferometry. The device employed allowed researchers to monitor molecular motion at the atomic scale in a previously inaccessible time range (between 10 nanoseconds and 10 microseconds), as well as "isolate the signature" of Johari-Goldstein relaxation. The findings, published in Nature Physics, challenge long-held notions that beta relaxation is a discrete, autonomous occurrence. Rather, it is a direct prelude to structural relaxation: it is the first indicator of molecular cage collapse, which eventually leads to the material's fluidity. While the finding does not contradict earlier models, it does show that the distinction between different types of relaxation is more formal than substantive: at the microscopic level, the dynamics are inextricably linked.