Research
My research is rooted in statistical physics, with a broad interest in complex systems and the emergence of collective phenomena. I develop analytical and computational approaches to understand how fluctuations, interactions, geometry and confinement determine the behaviour of physical systems across different length and time scales.
My work ranges from quantum and thermal fluctuation-induced interactions at the nanoscale to nonlinear and nonlocal flows in granular materials, and from the physics of urban environments to the quantitative modelling of human performance and physiological dynamics. A recurring motivation is to identify general principles connecting seemingly different problems and to develop theoretical methods that can be tested against experiments and real-world observations.
Fluctuation-Induced Interactions and Confined Fluctuations
Quantum and thermal fluctuations can generate effective forces between objects, even in the absence of externally applied fields. These fluctuation-induced interactions, including quantum, critical and non-equilibrium Casimir forces, depend sensitively on the geometry, material properties and spatial arrangement of the interacting bodies.
A central focus of my research has been the development of theoretical methods for describing such interactions beyond simple planar geometries. Together with collaborators, I developed scattering approaches that combine quantum and statistical field theory with classical wave scattering. More recently, I developed a systematic multiple-surface-scattering expansion that allows Casimir interactions between dielectric objects of arbitrary shape to be studied without requiring their scattering amplitudes in advance.
Current research extends these methods towards experimentally relevant nanostructures and atom-surface interactions. More recently, I am interested in related questions involving confined fluids, deformable objects and fluctuation-mediated interactions in hydrodynamic and nonequilibrium systems.
Granular Matter and Emergent Cooperativity in Nonlocal Flows
Granular materials such as sand and powders display complex flow behaviour that differs fundamentally from ordinary fluids. In dense granular systems, the local flow rate cannot always be determined from the local stress alone: rearrangements in one region can influence the motion of grains elsewhere, leading to strongly nonlocal and cooperative dynamics.
My current research investigates how such collective effects can be described within continuum theories and how confinement and non-linearities determine the emergence of characteristic flow scales. In collaboration with researchers at PMMH, I am developing a nonlocal rheological approach to shear localization in granular materials, combining continuum equations, analytical methods and numerical techniques for partial differential equations.
A broader objective is to understand how nonlocality emerges from microscopic grain rearrangements and how it affects the macroscopic motion and interactions of objects immersed in granular flows. These questions connect statistical physics with continuum mechanics, hydrodynamics and fluid-structure interactions.
Physics Concepts in Exercise Physiology
Human exercise and physiological dynamics provide an interesting setting for applying concepts and methods from physics. The growing availability of wearable sensors makes it possible to study performance, training and physiological responses under real-world conditions, complementing traditional laboratory experiments.
I developed a mathematical model of human running performance based on metabolic power and endurance, describing performances over distances from approximately 800 metres to the marathon. In collaboration with Polar Electro, this approach was applied to about 1.6 million exercise sessions from 14,000 runners, demonstrating how individual performance characteristics can be extracted from large-scale wearable data.
A complementary research direction concerns fluctuations and correlations in heart-rate variability during exercise, using methods for analysing nonstationary physiological time series.
Current work extends these approaches to environmental exposure during physical activity, combining wearable physiological measurements with mobile air-quality sensors and spatial pollution data to develop physics inspired models to understand how urban environments affect physiological responses.
Urban Physics and Climate
Cities constitute complex physical systems in which geometry, material properties and energy exchange strongly influence local environmental conditions. One important example is the urban heat-island effect, where urban areas can remain significantly warmer than their surroundings, particularly at night.
My research applies methods from statistical physics and radiative-transfer theory to understand how the three-dimensional structure of cities influences thermal radiation and surface temperatures. By combining physical models of multiple radiative reflections between buildings with geospatial information, we developed approaches for predicting the spatial distribution of urban surface temperatures.
In collaboration with researchers at New York University, these models were compared with thermal measurements from New York City, demonstrating how detailed urban geometry can be incorporated into quantitative environmental modelling.
This research provides a foundation for broader investigations of urban climate, environmental heterogeneity and the interaction between built environments and human exposure.
Earlier Research
My earlier research has addressed a range of problems in statistical and condensed-matter physics, including disordered elastic systems, quantum magnets, superconductivity, critical phenomena and collective transport. These studies have involved analytical approaches to interacting and disordered systems, field-theoretical methods and numerical modelling. They form part of the broader theoretical background from which my more recent research directions have developed.