Highlights of Max Planck Institute for the Physics of Complex Systems

Listening to hidden signals: how biological systems optimise inaccessible information

Thu, 17 Oct 2024 22:00:00 +0200

Living organisms must sense and process information from their surroundings to survive, but they often cannot directly “listen” to external signals. For example, the internal processes of a red blood cell can only access the external world through the cellular membrane, but how well can this membrane transmit such information? And how can information transmission be achieved with a limited energy budget? Giorgio Nicoletti of EPFL Lausanne and Daniel Busiello of the Max Planck Institute for the Physics of Complex Systems have now shown that, by optimising energy and information at the same time, biological systems can tune themselves to harvest maximal information from the environment. These highly efficient strategies require a price in terms of energy consumption, but this price is far outweighed by the information learned about the hidden, external signals. A particularly relevant case study for these results is red blood cells: The authors quantify how much information about the state of the internal cytoskeleton is transmitted into the flickering of their membrane, unraveling a deep connection between healthy cellular conditions, energy dissipation, and information. In particular, the mechanical stress of the cell affects its efficiency in terms of how well information is transmitted, providing novel and fundamental insights into the functioning of biological systems in complex environments. Giorgio Nicoletti and Daniel Maria Busiello, Phys. Rev. Lett. 133, 158401 (2024) Selected for a Viewpoint in Physics.

Counterdiabatic driving for periodically driven systems

Mon, 07 Oct 2024 22:00:00 +0200

Periodically driven systems have emerged as a useful technique to engineer the properties of quantum systems, and are in the process of being developed into a standard toolbox for quantum simulation. An outstanding challenge that leaves this toolbox incomplete is the manipulation of the states dressed by strong periodic drives. To achieve fast control of nonequilibrium quantum matter, Paul Schindler and Marin Bukov of the Max Planck Institute for the Physics of Complex Systems have now generalised the notion of variational counterdiabatic driving away from equilibrium. The researchers discuss applications to two-level, Floquet band, and interacting periodically driven models. Paul M. Schindler and Marin Bukov, Phys. Rev. Lett. 133, 123402 (2024)

The call for the 2025 Distinguished PKS Postdoctoral Fellowship is open!

Tue, 01 Oct 2024 10:04:00 +0200

The application deadline for this call is the 15 of November 2024. Distinguished PKS postdoctoral fellows appear personally along with the departments and groups on the main research page of the institute and are expected to have at least one year of postdoctoral experience at an institution other than the one at which their PhD was awarded. Applications for this fellowship directly after completion of the PhD might be considered in exceptional cases. Please click on the button to see the full advertisement!

Leader cells created with light cannot pull cell trains on their own

Mon, 30 Sep 2024 22:00:00 +0200

In biological processes such as embryonic development, wound healing, and cancer invasion, cells move in cohesive groups. These groups are often led by a so-called leader cell, which is thought to pull and direct the followers. New work by Ricard Alert of the Max Planck Institute for the Physics of Complex Systems and his experimental collaborators in the group of Xavier Trepat at the Institute for Bioengineering of Catalonia (IBEC) now shows that the local action of a leader is not enough to guide the migration of cell groups. Instead, the researchers show that mechanical coordination across the entire cell group is needed for the group to move. To test whether leader cells can pull others, the scientists used genetically-modified cells that turn into leaders when illuminated with blue light. In this way, the team could create leader cells on demand. The researchers then studied whether leader cells could act as the locomotive of small cell trains, up to four cells long. They found that a leader cell can robustly drag one follower but not longer cell trains. Leader cells therefore need the contribution of followers to guide the group. Ricard Alert then developed a physical model that shows how the motion of cell trains arises from asymmetries in cellular traction forces across the entire cell train, in agreement with the team’s experimental measurements. The new work therefore challenges the notion of autonomous leader cells, and it shows that cells need to coordinate their forces to move in groups. More details can be found in the press release (PDF). Leone Rossetti, Steffen Grosser, Juan Francisco Abenza, Léo Valon, Pere Roca-Cusachs, Ricard Alert, and Xavier Trepat. Optogenetic generation of leader cells reveals a force–velocity relation for collective cell migration, Nat. Phys. (2024)

Patrick Lenggenhager receives SPS thesis award

Mon, 23 Sep 2024 10:49:55 +0200

Every year, the Swiss Physical Society (SPS) awards a few young physicists for outstanding research work during their doctoral studies. This year, Patrick Lenggenhager, who joined MPI-PKS last year as a postdoc, is the recipient of the SPS award for condensed matter physics. In his doctoral thesis, Patrick explored multigap topology and hyperbolic lattices, two emerging avenues in band theory that are tied together by the overarching concepts of symmetry and topology. His findings advance the state of the art in these two key frontiers and underscore the centrality of band theory as a tool to uncover novel physical phenomena. We would like to congratulate Patrick on this impressive achievement and celebrate his contributions to condensed matter physics, which are sure to grow even larger in the coming years!

Lifting the Veil of Topological Censorship

Fri, 20 Sep 2024 22:00:00 +0200

Topological protection provides unprecedented robustness of physical phenomena against all kinds of perturbations; but in doing so, it exercises topological censorship by hiding all kinds of interesting and important microscopic information. Recent experiments have collected microscopic information precisely of the kind hidden by such Topological Censorship. The work by Douçot, Kovrizhin and Moessner provides a detailed microscopic theory which goes beyond such topological censorship. It not only identifies an unexpected phenomenon – the meandering edge state carrying topologically quantised current – at variance with common expectations; but also identifies mechanisms which allow for tuning between qualitatively different microscopic implementations corresponding to one and the same topologically protected global quantity. More details can be found in the press release (PDF). Benoit Douçot, Dmitry Kovrizhin, and Roderich Moessner, Proc. Natl. Acad. Sci. USA, 121, e2410703121 (2024)

Libor Šmejkal receives ERC starting grant

Wed, 11 Sep 2024 12:05:00 +0200

The European Research Council (ERC) has announced prestigious starting grants to researchers to set up their own teams and conduct research on the topics of their choice. One of these researchers is Libor Smejkal, a new group leader at MPI-PKS & MPI-CPfS, with his successful proposal on "Magnetic counterparts of unconventional superconductors for spin-conserved and non-dissipative electronics". The project will explore topological and quantum variants of unconventional magnets that are analogues to unconventional superfluids and superconductors. Libor's group will also search for realistic material candidates enabling low-dissipation electronics based on the unconventional magnetism. Congratulations!!

New group at the institute: Functional Quantum Matter

Wed, 11 Sep 2024 10:00:00 +0200

We cordially welcome Libor Šmejkal as a new group leader at the institute! Libor joins us from the University of Mainz and establishes the Functional Quantum Matter group at MPI-PKS jointly with MPI-CPfS. The group studies complex quantum solid-state systems, focusing on unconventional magnets such as altermagnets, and topological materials. Libor and his team investigate these systems by developing analytical and computational tools based on symmetry and ab initio electronic structure theory. The aim is to achieve fundamental theoretical but experimentally testable scientific advances with potential functionalities in future energy-efficient, sustainable, and ultra-scalable nanoelectronics and spintronics. Welcome Libor!

Moving together despite turning away

Tue, 16 Jul 2024 22:00:00 +0200

Self-propelled agents such as birds, cells, and active colloidal particles often move collectively in flocks. In the paradigmatic Vicsek model, flocking emerges due to alignment interactions between the active agents, which align much in the same way as spins do. Suchismita Das, Matteo Ciarchi, Ricard Alert of the Max Planck Institute for the Physics of Complex Systems and their collaborators have now discovered that flocking can emerge even if the agents turn away from each other. The researchers made this surprising discovery in experiments with self-propelled colloidal particles that repel more strongly in their front half than in their rear half, in such a way that they turn away from each other. They then used simulations and two types of kinetic theory to explain how these particles end up flocking. Their theory revealed that repulsion between the particles is key: When two particles interact, repulsion pushes them apart before they can turn away too much, thus producing effective alignment, as shown in the figure. This crucial role of repulsion is surprising as repulsion is not even an ingredient in the paradigmatic models of flocking, such as the Vicsek model, where collective motion emerges just from alignment interactions between particle orientations. The new work also showed that, via repulsion, the particles can form flocking crystals, which are active counterparts of Wigner crystals formed through electrostatic repulsion in electron gases. In conclusion, these active particles move in the same direction as a compromise between turning away from left and right neighbors. This mechanism of flocking could potentially be relevant for certain cells, which also turn away from each other upon collision via a process known as contact inhibition of locomotion. Whether these findings can explain how cells flock remains an open question for future work. Suchismita Das, Matteo Ciarchi, Ziqi Zhou, Jing Yan, Jie Zhang, and Ricard Alert, Phys. Rev. X 14, 031008 (2024)

Prof. Matthieu Wyart awarded the "Physik Preis Dresden 2024"

Wed, 19 Jun 2024 11:49:00 +0200

Prof. Matthieu Wyart awarded the Physik Preis Dresden 2024

On 18 June 2024, the French physicist Prof. Matthieu Wyart (EPFL, École Polytechnique Fédérale de Lausanne) was awarded the Physik Preis Dresden 2024. The theoretical physicist is being honoured for his pioneering contributions to various problems of complex systems, in particular the theory of financial markets, the physics of disordered and glassy systems as well as the theory of neural networks and machine learning. The Physik Preis Dresden is awarded annually jointly by the Dresden University of Technology and the Max Planck Institute for the Physics of Complex Systems (MPI-PKS).

Matthieu Wyart completed his PhD in Paris in 2005, where he worked together with J.-P. Bouchaud. During this time, he developed a model of price response functions in electronic markets, which became a standard in the industry. In the field of physics of disordered systems, he made an important breakthrough very early on by explaining how the surplus of soft modes in closely-packed systems of particles is controlled by their disordered geometry. This work elegantly solved the long-standing problem of the origin of the so-called boson peak in glasses with repulsive interactions. As a postdoc, he moved to Harvard and then Princeton before becoming an assistant and associate professor at New York University. He has been a professor at EPF Lausanne since 2015.

In recent years, Matthieu Wyart's original approaches and way of reasoning have had a strong impact and brought new insights into the physics of disordered systems. More recently, he has made significant contributions to the problem of the nature of the glass transition. In particular, his work suggests that increasing local energy barriers control the slowing down of dynamics in supercooled liquids, as opposed to co-operative effects.

The numerous original approaches to solving problems in different fields and disciplines are testimony to his extraordinary scientific excellence. In recognition of his outstanding contributions to the physics of complex and disordered systems, the Dean of the Faculty of Physics at Dresden University of Technology, Prof. Gesche Pospiech, together with Prof. Frank Jülicher, Director at the MPI-PKS, awarded the Physik Preis Dresden 2024 to Matthieu Wyart on 18 June 2024 as part of the Physics Colloquium.

About the Physik Preis Dresden

The Physik Preis Dresden, endowed with 5,000 euros, was founded in 2015 by the Dresden physicist Prof Peter Fulde (1936-2024), the founding director of the MPI-PKS, and has been awarded annually to renowned scientists since 2017. The award winners are selected by a joint commission of the Dresden University of Technology and the MPI-PKS. In addition to the central criterion of scientific excellence, it is particularly important for the decision that the work of the award winners is of particular importance for the cooperation between the two DRESDEN-concept partners MPI-PKS and TUD and that their connection has been further strengthened in the long term.

More about the Physik Preis Dresden

Quantum skyrmion Hall effect

Mon, 10 Jun 2024 22:00:00 +0200

The framework of the quantum Hall effect has been extended to a framework of a quantum skyrmion Hall effect by Ashley Cook of the Max Planck Institute for the Physics of Complex Systems and the Max Planck Institute for Chemical Physics of Solids, by generalizing the notion of a particle to include compactified p-dimensional charged objects. This is consistent with three sets of topologically non-trivial phases of matter previously discovered by Cook and collaborators: the topological skyrmion phases of matter, the multiplicative topological phases of matter, and the finite-size topological phases of matter. These findings indicate that topological states of D-dimensions can persist after compactification and yield previously unidentified generalizations of particles, a finding of relevance to many areas of physics, and particularly string theory, with great potential for rapid experimental confirmation. Ashley Cook, Phys. Rev. B 109, 155123 (2024)

Quantum Electrodynamics in 2+1 Dimensions as the Organising Principle of a Triangular Lattice Antiferromagnet

Fri, 26 Apr 2024 22:00:00 +0200

Quantum electrodynamics (QED) is the fundamental theory that describes the interactions between electrons and photons. Its success has led some to wonder whether quantum field theories, like QED, can describe quasiparticles in a solid. These collective excitations include phonons, which describe lattice vibrations, and magnons, which are waves in a magnetic material, but might also be of a more exotic nature. In a recent study, Alexander Wietek of the Max Planck Institute for the Physics of Complex Systems and his collaborators show that QED in two spatial dimensions can be observed in frustrated antiferromagnets. An antiferromagnet is a material in which neighbouring electron spins in the crystal lattice would like to point in opposite directions. However, in certain geometries, such as a triangular lattice, it is impossible to have all neighbouring spins align in precisely the opposite way. This is called geometric frustration and can lead to strong disorder in the system. This disorder is not featureless, however. In fact, it is shown that the quasiparticles of such a spin soup, known as a quantum spin liquid, are related one-to-one to excitations of QED. Importantly, even the elusive magnetic monopoles, among a wide variety of other particle-hole excitations, are observed. The precise understanding of the spin-liquid state with magnetic monopoles as elementary excitations is a key step to discovering these exotic quasiparticles in antiferromagnetic materials. It is unlikely that the founders of QED would have predicted such a surprising emergence in condensed matter. Alexander Wietek, Sylvain Capponi, and Andreas M. Läuchli, Phys. Rev. X 14, 021010 (2024) Selected for a Viewpoint in Physics.

Bioenergetic costs and the evolution of noise regulation by microRNAs

Wed, 28 Feb 2024 22:00:00 +0100

MicroRNAs (miRNAs) are short strands of genetic material that regulate various cellular functions and developmental processes. One of the regulatory functions of miRNAs is noise control that confers robustness in gene expression. The interaction with their target messenger RNA (mRNA) requires a specific binding sequence of 6-8 nucleotide pairs in length. There are a variety of open questions about the evolution of miRNA regulation regarding their functional efficiency and binding specificity. Efe Ilker of the Max Planck Institute for the Physics of Complex Systems and Michael Hinczewski (Case Western Reserve University) show that this regulation incurs a steep energetic price, so that natural selection may have driven such systems towards greater energy efficiency. This involves tuning the interaction strength between miRNAs and their target messenger RNAs, which is controlled by the length of a miRNA seed region that pairs with a complementary region on the target. They show for the first time that microRNAs lie in an evolutionary sweet spot that may explain why 7 nucleotide pair interactions are prevalent: sequences that are much longer or shorter would not have the right binding properties to reduce noise optimally. To achieve this, they develop a stochastic model of miRNA noise regulation, coupled with a detailed analysis of the associated metabolic costs and binding free energies for a wide range of miRNA seeds. Moreover, the behaviour of the optimal miRNA network mimicks the best possible linear noise filter, a classic concept in engineered communication systems. These results illustrate how selective pressure toward metabolic efficiency has potentially shaped a crucial regulatory pathway in eukaryotes. Efe Ilker and Michael Hinczewski, Proc. Natl. Acad. Sci. USA 121, e2308796121 (2024)

Characterising the gait of swimming microorganisms

Thu, 01 Feb 2024 22:00:00 +0100

The survival strategies of Escherichia Coli are controlled by their run-and-tumble "gait". While much is known about the molecular mechanisms of the bacterial motor, quantifying the motion of these microorganisms in three dimensions has remained challenging. Christina Kurzthaler of the Max Planck Institute for the Physics of Complex Systems and her collaborators have now proposed a high-throughput method, using differential dynamic microscopy and a renewal theory, for measuring the run-and-tumble behavior of a population of E. Coli cells. Besides providing a full spatiotemporal characterisation of their swimming gait, this new method allowed relating, for the first time, molecular properties of the motor to the dynamics of engineered E. coli cells. It therefore lays the foundation for future studies on gait-related phenomena in different microorganisms and has the potential of becoming a standard tool for rapidly determining motility parameters of swimming cells. More details can be found in a press release (PDF). C. Kurzthaler*, Y. Zhao*, N. Zhou, J. Schwarz-Linek, C. Devailly, J. Arlt, J.-D. Huang, W. C. K. Poon, T. Franosch, J. Tailleur, and V. A. Martinez, Phys. Rev. Lett. 132, 038302 (2024) Y. Zhao*, C. Kurzthaler*, N. Zhou, J. Schwarz-Linek, C. Devailly, J. Arlt, J.-D. Huang, W. C. K. Poon, T. Franosch, V. A. Martinez, and J. Tailleur, Phys. Rev. E 109, 014612 (2024) Selected for a Synposis in Physics.

Exotic fractons constraining electron motion to one dimension

Mon, 22 Jan 2024 22:00:00 +0100

Fractons are the latest addition to the set of exotic quasiparticles in condensed matter, and models exhibiting fracton phenomenology are highly sought after. Alexander Wietek of the Max Planck Institute for the Physics of Complex Systems and his collaborators have now proposed a model that shows this phenomenology. They studied a simple "doped" Ising magnet on the two-dimensional honeycomb lattice with anisotropic Ising couplings that exhibits a dipolar symmetry. This peculiar property leads to the complete localization of one hole, whereas a pair of two holes is localized only in one spatial dimension. The emergent dipole symmetry is found to be remarkably precise, being present up to the 15th order of perturbation theory and to numerically accurate precision away from the perturbative limit. The proposed model captures the very essence of subdimensional mobility constraints and could become a prime example of how new and exotic fracton-like quasiparticles can be implemented in a condensed matter setting. Sambuddha Sanyal, Alexander Wietek, and John Sous, Phys. Rev. Lett. 132, 016701 (2024)

Using quantum computers to test Jarzynski’s equality for many interacting particles

Fri, 17 Nov 2023 22:00:00 +0100

Statistical mechanics is a branch of physics that uses statistical and probabilistic methods to understand the behaviour of large numbers of microscopic particles, such as atoms and molecules, in a system. Instead of focusing on the individual motion of each particle, statistical mechanics analyses the collective properties of the system. It provides a bridge between the microscopic world of particles and the macroscopic world that we can observe, explaining phenomena like the behaviour of liquids and gases, phase transitions, and the thermodynamic properties of materials. Through the statistical distribution of particle properties, such as energy and velocity, statistical mechanics helps us make predictions about how physical systems behave on a larger scale, contributing to our understanding of fundamental principles in physics and chemistry. One of the most remarkable relations in statistical mechanics is Jarzynski's equality, connecting the irreversible work performed in an arbitrary thermodynamic process with the energy and entropy of the system in thermodynamic equilibrium. Because the system is free to leave the equilibrium state during its evolution, Jarzynski’s equality is a prime example of how equilibrium physics can constrain the outcome of nonequilibrium processes. Remarkably, the familiar Second Law of Thermodynamics – a fundamental principle of physics – follows directly from Jarzynski’s equality. The Second Law is a statement about the average properties of particles in a system undergoing a thermodynamic process, and postulates that heat always flows spontaneously from hotter to colder regions of the system. Intriguingly, Jarzynski’s equality shows that this fundamental law of Thermodynamics can be “violated” in individual realizations of a process (but never on average!). Despite its fundamental importance, experimental tests of Jarzynski’s equality for classical and quantum systems are extremely challenging, since they require complete control in manipulating and measuring the system. Even more so, a test for many quantum interacting particles was until recently completely missing. In a new joint study, an international team from the Max Planck Institute for the Physics of Complex Systems, the University of California at Berkeley, the Lawrence Berkeley National Laboratory, the German Cluster of Excellence ML4Q and the Universities of Cologne, Bonn, and Sofia identified quantum computers as a natural platform to test the validity of Jarzynski’s equality for many interacting quantum particles. (A quantum computer is a computing device that uses the principles of Quantum Mechanics to perform certain types of calculations at speeds and efficiency levels that are unattainable by classical computers. Quantum computers use quantum bits, or qubits, as the basic unit of information. Hence, any quantum computer is, at its core, a system of interacting quantum particles.) The researchers used the quantum bits of the quantum processor to simulate the behaviour of many quantum particles undergoing nonequilibrium processes, as is desired for an experimental verification of Jarzynski’s equality. They tested this fundamental principle of nature on multiple devices and using different quantum computing platforms. To their surprise, they found that the agreement between theory and quantum simulation was more accurate than originally expected due to the presence of computational errors, which are omnipresent in current quantum computers. The results demonstrate a direct link between certain types of errors that can occur in quantum computations and violations of Jarzynski’s equality, revealing a fascinating connection between quantum computing technology and this fundamental principle of physics. Dominik Hahn, Maxime Dupont, Markus Schmitt, David J. Luitz, and Marin Bukov, Physical Review X 13, 041023 (2023)

Investigating the impact of a defect basepair on DNA melting

Fri, 10 Nov 2023 22:00:00 +0100

As temperature is increased, the two strands of DNA separate. This DNA melting is described by a powerful model of statistical physics, the Poland–Scheraga model. It is exactly solvable for homogeneous DNA (with only one type of basepairs), and predicts a first-order phase transition. Arthur Genthon of the Max Planck Institute for the Physics of Complex Systems, Albertas Dvirnas and Tobias Ambjörnsson (Lund University, Sweden) have now derived an exact equilibrium solution of an extended Poland–Scheraga model that describes DNA with a defect site that could, for instance, result from DNA basepair mismatching, cross-linking, or the chemical modifications from attaching fluorescent labels, such as fluorescent-quencher pairs, to DNA. This defect was characterized by a change in the Watson–Crick basepair energy of the defect basepair, and in the associated two stacking (nearest-neighbour) energies for the defect compared to the remaining parts of the DNA. The exact solution yields the probability that the defect basepair and its neighbors are separated at different temperatures. In particular, the authors investigated the impact of the defect on the phase transition, and the number of base pairs away from the defect at which its impact is felt. This work has implications for studies in which fluorophore-quencher pairs are used to analyse single-basepair fluctuations of designed DNA molecules. Arthur Genthon, Albertas Dvirnas, and Tobias Ambjörnsson, J, Chem. Phys. 159, 145102 (2023)

A Quantum Root of Time for Interacting Systems

Sun, 29 Oct 2023 22:00:00 +0100

In 1983, the two physicists Page and Wootters postulated a timeless entangled quantum state of the universe in which time emerges for a subsystem in relation to the rest of the universe. This radical perspective of one quantum system serving as the other’s temporal reference resembles our traditional use of celestial bodies’ relative motion to track time. However, a vital piece has been missing: the inevitable interaction of physical systems. Forty years later, Sebastian Gemsheim and Jan M. Rost from the Max Planck Institute for the Physics of Complex Systems have finally shown how a static global state, a solution of the time-independent Schrödinger equation, gives rise to the time-dependent Schrödinger equation for the state of the subsystem once it is separated from its environment to which it retains arbitrary static couplings. Exposing a twofold role, the environment additionally provides a time-dependent effective potential governing the system dynamics, which is intricately encoded in the entanglement of the global state. Since no approximation is required, intriguing applications beyond the question of time are within reach for heavily entangled quantum systems, which are elusive but relevant for processing quantum information. Sebastian Gemsheim and Jan M. Rost, Phys. Rev. Lett. 131, 140202 (2023)

New Max Planck Fellow group established at the institute

Thu, 19 Oct 2023 10:00:00 +0200

The Max Planck Fellows Programme promotes cooperation between universities and Max Planck institutes and enables a university professor to install a research group at an MPI. We are glad to announce that Prof. Jan Budich from TU Dresden has started a new Max Planck Fellow group "Dissipative Quantum Matter" at MPI-PKS. The research group will explore quantum many-body systems in which dissipation plays a crucial role, for example inducing novel phases of topological matter or enabling the controlled preparation of complex quantum states in the context of quantum simulators. Regarding physical platforms, the spectrum of interest ranges from quantum condensed matter to atomic and quantum-optical many-body systems. Welcome at the institute, Jan!

Unraveling the mysteries of glassy liquids

Wed, 18 Oct 2023 22:00:00 +0200

When a liquid is cooled to form a glass, its dynamic slows down significantly, resulting in its unique properties. This process, known as “glass transition”, has puzzled scientists for decades. One of its intriguing aspects is the emergence of “dynamical heterogeneities”, when the dynamics become increasingly correlated and intermittent as the liquid cools down and approaches the glass transition temperature. In a new collaborative study, Ali Tahaei and Marko Popovic from the Max Planck Institute for the Physics of Complex Systems, with colleagues from EPFL Lausanne, ENS Paris, and Université Grenoble Alpes, propose a new theoretical framework to explain the origin of the dynamical heterogeneities in glass-forming liquids. Based on the premise that relaxation in these materials occurs occurs through local rearrangements of particles that interact via elastic interactions, the researchers formulated a scaling theory that predicts a growing length-scale of dynamical heterogeneties upon decreasing temperature. The proposed mechanism is an example of extremal dynamics that leads to self-organised critical behavior. The proposed scaling theory also accounts for the Stokes-Einstein breakdown, which is a phenomenon observed in glass-forming liquids in which the viscosity becomes uncoupled from the diffusion coefficient. To validate their theoretical predictions, the researchers conducted extensive numerical simulations that confirmed the predictions of the scaling theory. Ali Tahaei, Giulio Biroli, Misaki Ozawa, Marko Popovic, and Matthieu Wyart, Phys. Rev. X 13, 031034 (2023).