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EMERGENCE AT ALL SCALES - 1st ANNUAL MEETING
7th & 8th April 2026 | @OBA (Amsterdam Public Library, 6th floor), Oosterdokskade 143, 1011 DL Amsterdam, Netherlands
1st ANNUAL MEETING
T​he NWA ORC Consortium Emergence at all Scales invites everyone to attend its first annual meeting where topics within its focus will be discussed, including hydrodynamics, complexity, collective phenomena, synchronization, phases of matter, social physics, etc. The preliminary program, including plenary speakers can be found below.
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Programme 7th of April:
09:00 - 10:00: Walk-in, tea and coffee
10:00 - 10:15: Opening remarks |room Prinsen/Keizerszaal
10:15 - 11:10: Michal Heller on hydrodynamics and complexity
11:10 - 11:25: Coffee break
11:25 - 12:55: Parallel session | Quantum spacetime and emergent structures (Ruth Gregory, B. Freivogel, P. Schikhof) |room Prinsen
11:25 - 12:55: Parallel session | Emergence of hydrodynamics (Wout Merbis and Ruben Lier) | room Herenzaal
11:25 - 12:55: Parallel session | Cosmic structures (Angelo Caravano, Margharita Putti, Juan Fernandez Molinero) | room Singelzaal
12:55 - 14:20: Lunch break
14:20 - 15:15: Ruth Gregory on analogue black holes | room Prinsen/Keizerszaal
15:15 - 15:30: Coffee break
15:30 - 17:00: Parallel session | Gravity and dark structure (Daniel Frolovsky, Luka Vinck, Cisca Kalmijn) | room Singelzaal
15:30 - 17:00: Parallel session | Collective behaviour in networks and life-like matter (K. Krischer, Stan Koenis, Mollie Brown) | Prinsen
15:30 - 17:00: Parallel session | Quantum matter (speakers: Alix McCollam, Sebastian Bahamondes) | room Herenzaal
17:00 - 18:00: Borrel + meet societal partners
18:00 - 20:00: Dinner
20:00 - ++++ : Social activities
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Programme 8th of April:
09:00 - 09:30: Walk-in, tea and coffee
09:30 - 10:25: Katharina Krischer on synchronization |room Prinsen/Keizerszaal
10:25 - 11:10: EAAS and Society: Update
11:10 - 11:40: Coffee break
11:40 - 12:35: Summaries of ongoing progress from parallel sessions
12:35 - 14:00: Lunch and posters
14:00 - 14:55: Hartmut Löwen on emergent properties of intelligent matter
14:55 - 15:30: Meet the PhDs and Postdocs
15:30 - 16:00: Coffee break
16:00 - 16:55: Frank Pijpers on social physics
16:55 - 17:15: Discussion
17:15 - 18:15: Borrel + departure
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Location: OBA (Amsterdam Public Library, 6th floor), Oosterdokskade 143, 1011 DL Amsterdam, Netherlands
Invited speakers
Michal Heller
(U. Ghent)
Frank Pijpers
(CBS/UvA)
Ruth Gregory
(Kings College London)
Alix McCollam
(U. Cork)
Katharina Krischer
(Technische Universität München)
Hartmut Löwen
(Heinrich-Heine University of Düsseldorf)
Abstract (Michal Heller): Universal dynamics far from equilibrium
Black holes are arguably the harmonic oscillators of the 21st century. I will describe how their fundamental properties have reshaped our understanding of universal far-from-equilibrium dynamics and its emergence. Examples include the growth of complexity in quantum many-body systems, the onset of hydrodynamics in ultrarelativistic nuclear collisions at RHIC and the LHC, and self-similar dynamics observed in cold-atom experiments.
Abstract (Ruth Grefory): Black Hole Spectroscopy from a Giant Quantum Vortex
Black-hole spectroscopy aims to infer physical properties of black holes by detecting the spectrum of quasi-normal modes (QNMs) they emit while settling towards equilibrium. Gravitational analogs aim to explore aspects of black hole systems by building laboratory experiments that share features of the black hole and its perturbations. A particularly interesting aspect of QNMs is the phenomenon of spectral instability: the complex frequencies of the modes wander as perturbations of the spacetime around the black hole are introduced. Having the ability to simulate in a controlled environment the behaviour of these modes is therefore appealing. I will describe the quantum vortex analog recently developed in the Nottingham Black Hole Laboratory and discuss the problem of how to identify the quasi-normal modes for such a confined system, as well as showing data from the experiment.
Abstract (Katharina Krischer): Transitions between high- and low-dimensional dynamics: The emergence of synchronization in coupled oscillators
One of the groundbreaking results in nonlinear dynamics over the last century was the understanding of how collective behavior emerges in coupled oscillators. This has contributed to our understanding of the dynamics of oscillatory networks across various disciplines and at all scales, from nanoelectromechanical systems in the micrometer range to power grids. Nevertheless, the dynamics of oscillatory networks continue to pose important, unsolved problems, such as the question of how high-dimensional incoherent states emerge from low-dimensional collective dynamics. I will discuss experimental examples of such transitions and demonstrate how they have helped uncover universal pathways between synchrony and incoherence depending on the type of coupling.
Abstract (Hartmut Löwen): Emergent behavior in active and living matter: towards intelligent particles
While ordinary materials are typically composed of inert "passive" particles, active matter comprises objects or agents which possess an intrinsic propulsion. Examples are living systems like schools of fish, swarms of birds, pedestrians and swimming microbes but also artificial particles equipped with an internal motor such as robots and colloidal Janus particles. Active matter is praised for possible technological applications ranging from micro-surgery to environmental cleaning. This talk provides an introduction to the basic physics of active matter with an emphasis on the statistical mechanics of synthetic artificial self-propelled particles. After an introduction of basic concepts to describe self-propelled colloids in the mesoscopic soft matter regime, such as active Brownian motion, novel emergent phenomena are described including motility-induced phase separation and active bacterial turbulence. Then the importance of inertia relevant for micro-robots of larger size is discussed with unusual emergent effects such as self-sustained cooling. Finally some ideas for smart active materials equipped with artificial intelligence will be proposed.
Abstract (Frank Pijpers): Sociophysics: translating collective behaviour insights from particles to people
The social and behavioural sciences are not widely perceived as having a strong quantitative model-building aspect, even though statistical analyses, of for instance survey data, have long been part of the technical toolbox of these sciences. However, the most recent decade or two have witnessed a substantial growth of quantitative modelling effort in the behavioural sciences, where use is made of knowledge gained from statistical physics, soft matter physics, and complexity science. This cross-disciplinary research is now regularly referred to as sociophysics. In this talk I will present some of my own cross-disciplinary work in social and economic models and efforts at empirical validation of such models using the databases curated by the Dutch National Statistical institute (CBS) as well as other data sources.
Parallel session | Quantum spacetime and emergent structures
Abstract (Ruth Gregory): Acceleration in three dimensions
More than a century ago, Weyl found a metric describing an accelerating black hole - the "C-metric" - although the interpretation of this axisymmetric exact solution did not arrive until much later. The C-metric is a fascinating spacetime with a deformed horizon and a cosmic string connecting the black hole to asymptotic infinity, however the holography of such solutions is a bit more subtle. To explore such questions in a simpler set-up I've been working on 3D solutions in AdS. I will describe recent progress on acceleration in three dimensions, including accelerating "point particles" as well as BTZ-like solutions. I will also summarise recent work in progress on accelerating rotating 3D metrics, which turn out to have some interesting phenomenology.
Abstract (Ben Freivogel): Quantum gravity fluctuations at long distances
I will address the question: In what situations are perturbative quantum gravity effects important at distances much longer than the Planck scale? Among other examples, I will calculate the quantum fluctuations of the black hole horizon.
Abstract (Phine Schikhof): Exclusion process in a dynamic environment
An exclusion process describes particles that jump to their neighboring sites. By rescaling time and space, a deterministic evolution of the particle density can be found. This is called the hydrodynamic limit. An interesting question to ask is, what happens to the hydrodynamic limit if the space on which the particles move changes over time? This question is about the interaction between geometry and hydrodynamic limits. I'll discuss the first steps toward understanding this question.
Parallel session | Emergence of hydrodynamics
Abstract (Wout Merbis | 35+5min): Sociohydrodynamics of polarization and segregation: large-scale spatial patterns in society where noise matters
Spatial segregation and polarization in socio-economic systems are examples where collective patterns can emerge from interacting agents. At the microscopic level, paradigmatic agent-based models for segregation and polarization, such as Schelling’s model and the voter model, have been used to uncover mechanisms behind spatial pattern formation in society. Often phrased in terms of stochastic lattice models, a clear connection with macroscopic patterns observed in society is often missing. In this work, we discuss a coarse-grained description of Schelling’s model coupled to voter dynamics, that connects micro-economic decision making at the level of individual households to continuum equations governing the large-scale spatial dynamics of socio-economic variables. The resulting ‘sociohydrodynamic’ framework provides an effective field theory for the coupled dynamics of segregation and polarization, in which local incentives and social interactions generate macroscopic spatial organization. We pay special attention to the inclusion of noise in the theoretical framework, resulting in the fluctuating hydrodynamic description of segregation coupled to polarization dynamics. Using analytical arguments and numerical simulations we investigate how these two processes reinforce and reshape one another across spatial scales. We find that stochasticity plays a central role in this interplay. Noise can qualitatively modify the coupled segregation and polarization dynamics and leave persistent signatures in the resulting spatial patterns at urban and regional scales. Furthermore, we use the coupling to noise as a link between theoretical predictions (at the level of the power-spectrum), stochastic simulations and empirical calibration. While the latter is still ongoing work, the framework itself is designed to interface with spatial socio-economic data, made available at grid level resolution through Statistics Netherlands. It therefore provides a route toward connecting mechanistic models of collective social dynamics with future data-driven analyses of segregation, polarization, and economic inequality.
Abstract (Ruben Lier | 35+5min): Emergence of a chiral fluid
The Navier–Stokes equations have provided a remarkably successful description of fluid flow for more than 150 years. A minimal yet profound extension of this framework is odd viscosity: it arises when time-reversal symmetry is broken and introduces non-dissipative stresses that fundamentally alter fluid flow. Odd viscosity typically arises through one of two mechanisms, both of which I will discuss in this talk. I will begin with the case of a background magnetic field. Through the Senftleben–Beenakker effect, a magnetic field can produce odd viscosity in a gas composed of nonspherical particles, even when the particles are neutral. I will show how, in such a chiral fluid, tracer particles of different shapes experience different transverse forces when sedimenting through the fluid, allowing them to be sorted by shape. I will then turn to a second mechanism, in which particles in a gas are set into rotation so that their collisions become chiral, turning the system into a spinner fluid. What makes the treatment of spinner fluids challenging is that they are typically considered to be driven out of equilibrium, rendering standard kinetic theory approaches unfeasible. I will explain how collisions of rotating, noncircular two-dimensional particles can be mapped to disks with a collision rule based on a chiral effective radius, for which the equilibrium state can be straightforwardly found. This allows for an analytical computation of odd viscosity based on the Chapman–Enskog expansion, whose result can be corroborated by a many-particle simulation.
Parallel session | Quantum Matter
Abstract (Sebastian Bahamondes): Thermal and quantum phase transitions in a holographic anisotropic Dirac semimetal
In this presentation we build a phenomenological, strongly coupled quantum field theory in 2+1-dimensions through AdS/CFT holography, by building a 3+1 dimensional, negatively curved gravity theory with a SU(2) gauge field, and a scalar field in the adjoint of SU(2). We locate a phase transition between two distinct phases at zero and finite temperature, which are characterized through the dispersion relation of quasi-normal modes of probe fermions in the bulk, and correspond either to a Dirac semimetal or a band insulator. These phases are separated by a critical phase/critical point (depending if T>0 or T=0, respectively) where the band structure of boundary fermions exhibits semi-Dirac anisotropy. We characterize each phase at T=0 by explicit solutions to the bulk equations of motion in the infra-red, and determine that the critical point's spacetime is a Lifshitz geometry, whose dynamical critical exponent is approximately equal to 2. We also find that this anisotropy induces a non-trivial scaling of the shear viscosity-entropy density ratio with respect to temperature in the T→0 limit, and find evidence that the anisotropic phase of the system corresponds to a finite-temperature quantum critical phase.
Parallel session | Collective behaviour in networks and life-like matter
Abstract (Katharina Krischer | 30+5min): Frequency Clusters and Self-organized Triplet Locking in a Network of Globally Coupled Identical Kuramoto Oscillators with Inertia
Frequency clusters are states in networks of coupled oscillators characterized by the formation of multiple groups of oscillators, each with a different mean frequency. The most prominent example in which the formation of frequency clusters is discussed to play a role is the formation of frequency bands in the brain, as measured, for example, in electroencephalograms. In our group, we have experimental evidence for the occurrence of frequency clusters during the electropolishing of silicon wafers.
In the talk, I will discuss the origin of frequency clusters in the globally coupled Kuramoto model with inertia and identical oscillators, one of the simplest models that supports their formation. We focus on the formation of two and three frequency clusters in the thermodynamic limit. Using bifurcation analysis, we demonstrate that in both cases the frequency clusters emerge through homoclinic bifurcations. In the case of three frequency clusters, this necessarily entails the formation of a triplet locked state, characterized by rational relations among the mean frequency differences. The individual clusters may lose phase-synchrony via either transcritical or period doubling bifurcations.
Abstract (Stan Koenis | 25+5min): Memory and computation in hysteretic flow networks
In a world with ever-increasing demands for computation, the nascent field of unconventional computing has seen a surge of interest over the last years. This field aims to develop novel, energy-efficient methods of computing and memory storage by looking at physical systems such as biological networks or metamaterials. A promising approach for such research is the general concept of hysteresis due to its ties to history-dependent states and memory. The Preisach model describes hysteresis by introducing hysterons, a fundamental object which can be viewed as a two-state system with inherent hysteretic behaviour. This has been used to model a wide variety of phenomena, from ferromagnetism to capillary hysteresis in porous media. In our research, we consider a flow network of hysteron valves. Each valve can be in an “open” or “restricted” state, with distinct hydrodynamic conductances. Intuitively, the state of a single hysteron influences the flow throughout the entire network and can therefore influence the opening or closing of other valves. Hence, this behaviour can be seen as an interaction between hysterons. By characterizing and leveraging these interactions, we have been able to simulate a variety of rudimentary computing and memory devices, laying the foundation for more complex fluid-based computation.
Abstract (Mollie Brown | 25+5min): Graph polynomials as a theoretical framework for active matter systems
The Potts-Tutte connection between statistical mechanics and graph theory was discovered in the 1970’s. For the q-state Potts model on a lattice, the sum of all energy states of the system is remarkably equal to an evaluation of the lattice’s Tutte polynomial. In 2010, this result was extended by Ellis-Monaghan and Moffatt to establish an analogous relation between the q-state Potts model with external field, and the V-polynomial. We aim to generalise this relation even further: active matter systems such as the Cellular Potts Model present new challenges, namely by introducing variable edge energies on its associated lattice. In this talk, we present the classical Potts-Tutte relation, the more generalised Potts-V-polynomial relation, and ongoing progress and limitations in extending this relation to the Cellular Potts Model.
Parallel session | Gravity and dark structure
Abstract (Luca Vinck): Emergence of Time and Dynamical Laws in Quantum Cosmology
Recent applications of algebraic quantum field theory to quantum gravity in the AdS/CFT correspondence have raised the prospect that similar algebraic methods could underpin a form of holography in cosmological, de Sitter-type spacetimes. In this setting, the algebra of observables is associated not with an asymptotic boundary, but with the worldline of an observer. A key advantage of the operator-algebraic framework is that, while Hilbert space representations depend sensitively on the choice of spacetime background, the underlying ∗-algebraic structure does not — suggesting a notion of algebraic background independence in which the background enters only at the level of a representation or state. Explicit dressing of observables to an observer's worldline ensures that the algebra has a direct operational interpretation: it represents precisely what that observer can measure. The relational dynamics governing these observables is encoded in the Page–Wootters mechanism, while tools from Tomita–Takesaki modular theory can be used to derive an emergent notion of time from the algebraic structure itself, in the spirit of the Thermal Time Hypothesis. This project investigates the emergence of time and dynamics from the underlying operator-algebraic structure in gravitational and cosmological settings, bringing together perspectives from both physics and philosophy of physics.
Abstract (Cisca Kalmijn): Entropy and Noncommutative GeometryIn this talk we take a look at entropy in the setting of noncommutative (differential) geometry. We start by defining spectral triples and introduce the example of a 2-point space, which helps us illustrate the concepts throughout the talk. Next we translate concepts from physics such as second quantisation to our mathematical framework. We introduce the von Neumann entropy and study the relevant equilibrium states. Combining these tools, we get the entropy associated to a spectral triple.
Parallel session | Cosmic structures
Abstract (Angelo Caravano): How cosmic structure emerged from inflation: a simulation-based approach
Cosmological inflation is widely accepted as one of the leading scenarios for the generation of primordial fluctuations in the early Universe. The statistics of these fluctuations, from which all cosmic structures emerge, encode crucial information about physics at extremely high energies. In many well-motivated scenarios, however, accessing this information requires robust control of nonlinear dynamics, for instance in the presence of non-Gaussianity. In this talk, I will present a simulation-based approach that enables a fully nonlinear treatment of inflation, and I will show concrete examples where standard perturbative methods break down and fail to capture essential features of the dynamics. These results demonstrate that simulations are necessary to obtain reliable predictions in regimes relevant for current and upcoming observations. I will finally discuss how this approach enables a direct connection between inflation and observables across scales—including the cosmic microwave background, large-scale structure, and gravitational waves—opening the way to high-precision, first-principles tests of the early Universe.
Abstract (Margherita Putti): Inflating with a tachyonic spectator
Inflation provides the leading explanation for the origin of cosmic structure, with its predictions now tested to high precision by CMB observations. At the same time, observational constraints motivate the search for universal mechanisms that can modify the predictions of simple single-field models. I will present a model-independent multifield mechanism in which a spectator axion universally modifies inflationary predictions without direct couplings to the inflaton. The axion is stabilized at the hilltop of its potential during the observable phase of inflation and rolls off only after all relevant scales have exited the horizon. In its tachyonic phase, it enhances isocurvature fluctuations, which are transferred gravitationally to the curvature perturbation, amplifying the scalar power spectrum. This suppresses the tensor-to-scalar ratio r after normalization to the observed CMB amplitude, shifts the spectral index ns, and generates a characteristic primordial non-Gaussian signal. Because the axion rolls only after horizon exit, the effect is intrinsically scale-independent, making the mechanism a universal modification applicable to essentially any single-field inflationary model.
Abstract (Juan Molinero): A brief introduction to Asymptotically Safe Quantum Gravity
Asymptotically Safe Quantum Gravity (ASQG) constitutes an approach to describing gravitational interactions within the framework of quantum field theory, with the main goal of remaining predictive at all energy scales. In this talk, I will introduce the key ideas underlying this program and the role of the Functional Renormalization Group as its main computational tool. I will then discuss some ongoing studies of gravity–matter systems within this framework, and outline some future projects in ASQG research.
Registration
Registration is required before March 20th, please register here. Note that there is limited space available, therefore registration does not imply registration. We will send e-mail confirmation once we have made a selection if necessary.
Organisers
Jácome (Jay) Armas
(University of Amsterdam)
Mark Golden
(University of Amsterdam)
Maryam Shabestari
(University of Amsterdam)
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