Fluid dynamics is a well-established field with roots going back to Archimedes. Yet, its theoretical foundations continue to evolve, especially as new challenges and perspectives emerge. In recent years, modern techniques from theoretical physics have led to a reformulation of fluid dynamics from first principles, moving beyond traditional approaches that relied primarily on empirical observations. Crucially, this new framework enables the systematic inclusion of stochastic thermal fluctuations—tiny, random variations in the medium that can significantly influence the large-scale properties of the fluid, such as its viscosity. Understanding these effects is essential for accurately describing complex systems, particularly near phase transitions and in turbulent flows.
A striking real-world application appears in high-energy heavy-ion collisions at CERN’s Large Hadron Collider. In these extreme events, quarks and gluons are liberated from their parent nuclei and form a hot, dense, and strongly interacting fluid known as the quark-gluon plasma. As the plasma expands and cools, the quarks and gluons recombine into hadrons. Depending on the system’s energy and conserved charges, this recombination can happen smoothly or via a first-order phase transition, much like the freezing of water into ice. This behavior suggests the possible existence of a critical point—a special region in the QCD phase diagram where the smooth and abrupt transitions meet, and where fluctuations play a significant role. Locating this critical point is a major goal of current experimental and theoretical research.
This project has two main objectives. First, it aims to construct explicit scenarios where the new formulation of fluid dynamics can be applied—for example, in spin hydrodynamics, to study globally rotating plasmas. These spinning fluids naturally arise in non-central heavy-ion collisions, where the fluid’s internal spin and rotational motion become important and interact in subtle ways. The project also aims to develop a comprehensive framework for describing the physics near the QCD critical point using this modern fluid dynamics approach, thereby contributing directly to ongoing efforts to experimentally discover the critical point
The second goal is to explore deep and surprising connections between this reformulated fluid dynamics and the physics of black holes. In theoretical physics, black holes are not just astrophysical objects but also powerful tools for probing ideas in quantum gravity. Remarkably, black holes behave like thermodynamic systems—they have temperature and entropy—and, in certain contexts, they even exhibit fluid-like behavior near their horizons. This is especially apparent in the framework of the Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence, which links a gravitational theory in a higher-dimensional space to a quantum field theory without gravity in lower dimensions.
This project has made significant progress in applying the new formulation of fluid dynamics to physical systems relevant to heavy-ion phenomenology, while also uncovering deep connections between the symmetries of black hole horizons and those of hydrodynamic and chaotic systems. These results not only advance our theoretical understanding but also open new avenues for exploring the interplay between quantum gravity, fluid dynamics, and many-body quantum physics.
