The cosmological principle, which states that the Universe must be statistically isotropic and homogeneous on large scales, is a foundational principle of the standard model of cosmology, known as lambda cold dark matter ($\mathrm{\Lambda }$CDM). The validity of this principle can be tested by assessing the compatibility of a dipole anisotropy in the large-scale distribution of matter with the dipole observed in the cosmic microwave background, interpreted in the $\mathrm{\Lambda }$CDM model as due to our local peculiar motion. This Colloquium describes the methodology for such a test and presents its outcome based on the analysis of recent large catalogs of radio galaxies and quasars, revealing a significant inconsistency between the two dipoles. The authors review these recent findings, as well as potential biases, systematic issues, and alternate interpretations, and discuss how this anomaly could challenge the standard description of our Universe based on the $\mathrm{\Lambda }$CDM model.

The observation of a core collapse supernova explosion of (near-)Galactic origin would constitute a landmark, once-in-a-century event for multimessenger astronomy, eagerly awaited by observers and modelers alike. The detection of gravitational waves, along with photons and neutrinos, from such an event would provide unique insights into the supernova central engine and the physics of the newly forming neutron star. This Colloquium presents the latest progress in core collapse supernova modeling and the associated gravitational wave signal predictions. It also provides an overview of the specific methods of detection and physical parameter estimation that can be implemented for such signals in ground-based laser interferometers, in the context of multimessenger research strategies.

Supersymmetry remains one of the leading candidates for physics beyond the standard model, offering a compelling framework to address the hierarchy of scales. Its theoretical appeal has inspired decades of intensive model building and experimental searches. Recent results have placed stringent bounds on the supersymmetric parameter space, sharpening the focus on the remaining viable models. This review surveys the current status and outlook for supersymmetry in light of experimental constraints and recent theoretical developments, and presents projections for the discovery potential of the High-Luminosity Large Hadron Collider across multiple search channels and a variety of well-motivated scenarios.

Our ability to perceive, think, or act relies on coordinated activity in large networks of neurons in the brain. This review examines recent progress in connecting ideas from statistical physics, such as maximum entropy methods and the renormalization group, to quantitative experiments that record the electrical activity of thousands of neurons simultaneously. This quantitative bridge between the new data and statistical physics models uncovers new, quantitatively reproducible behaviors and makes clear that abstract theoretical principles in studies of the brain can have the level of predictive power that we expect in other areas of physics.

Frustration in spin systems can prevent ordering even at $T=0$, creating quantum spin liquids that have been sought since Anderson’s pioneering work in 1973 and his influential 1987 paper connecting them to high-temperature superconductivity. Kitaev’s solvable spin-1/2 models on a honeycomb lattice brought renewed attention to this field, with Jackeli and Khaliullin later revealing how to engineer Kitaev interactions in real materials. This review highlights theoretical and experimental developments in Kitaev spin liquids, emphasizing leading candidate materials and their broad topological properties such as chiral edge modes. Consequently, it provides essential insights for both experimentalists and theorists working on quantum spin liquid problems.

Dark sectors, involving new particles that couple very weakly to the standard model ones, play an important role in current model-building efforts in particle physics, as they allow, for example, for new dark matter production and interaction mechanisms. This review focuses on self-interacting dark matter scenarios, their implications on the dynamics and distribution of dark matter halos in the Universe, and the related astrophysical tests and observations, from galaxies to large-scale structures. It is embedded in the framework of the Novel Probes Project, a forum connecting observers and theorists involved in the study of astrophysical tests of dark-sector interactions.

This review updates the field of spin glasses with broad application to a large variety of physical systems. In particular, this review tracks the progress of experiment, theory, and large-scale simulations. It highlights the importance of their synergy, from the inception of the field to the present day, and includes future opportunities for research.

Cryptography not only involves the sending of secret messages but also encompasses many protocols and procedures that provide privacy and security in the networked world. Likewise, quantum resources have the potential to enhance cryptography in ways that go beyond the well-known example of quantum key distribution. This review offers a classification of the main crypto primitives that are available quantum mechanically. It explains the security that they offer, including the sometimes significant limitations on their theoretical capabilities. Implementations using current photonic techniques are discussed.

Neutron stars, the remnants of supernova explosions, are the densest objects in the Universe. A typical neutron star has a mass between one and two solar masses, and a radius of around 12 km. The density at the center of the star is higher than that in atomic nuclei. As a result, the properties of neutron stars provide important information about the behavior of ordinary matter under extreme compression. In recent years, new information about neutron stars has emerged from two sources. The first is the observation of the gravitational-wave signal from the final inspiral of a coalescing binary neutron star. The second is a careful measurement of the x-ray pulse profile of a spinning neutron star. This review discusses these measurements and summarizes how they constrain masses, radii, and central densities. The results are compared to predictions based on calculations of the nuclear equation of state at densities comparable to that in atomic nuclei, which are then extrapolated to higher density. The review ends with an outlook on future observational opportunities.