Ultrahigh dose rate, FLASH radiotherapy has emerged as one of the most promising innovations over the past decade in the field of radiation oncology, with the potential to eradicate radiation resistant primary tumors and improve the therapeutic outcome for cancer patients. FLASH is based on delivering radiation doses at ultrahigh dose rates (UHDR; $>40\mathrm{Gy}/\mathrm{s}$), more than 1000 times faster than irradiation at conventional dose rates (CONV). The experimental evidence demonstrating the differential effect of dose rate modulation on tumors and normal tissue is reviewed. Preclinical data consistently show that the antitumor efficacy of cytotoxic doses is not dependent on dose rate, but in normal tissues UHDR significantly reduces normal tissue toxicities compared to CONV, as observed in vivo. These observations define the FLASH effect. The FLASH effect has been reported to occur when using single or hypofractionated dose regimens in several experimental animal models (mice, rat, zebrafish, pig, and cats) and in multiple organs (lung, skin, gut, and brain) by numerous groups worldwide. Note that the FLASH effect has been demonstrated with electron, photon, and hadron (proton and heavier ion) beams. The current status and future technological development are reviewed, with an emphasis on critical beam parameters, future beam modalities, and prerequisites for safe clinical translation in terms of dosimetry, radioprotection, and treatment planning systems. Mechanistic investigations at the physicochemical and biological levels are presented, as are strategies to support and initiate clinical translation. This comprehensive review provides multidisciplinary radiation scientists with a road map of the technological, physical, chemical, biological, and clinical considerations that have made FLASH topical. These considerations are presented with a realistic and practical backdrop of the limitations and challenges that lie ahead.

Catalysts open up new reaction pathways that can speed up chemical reactions while not consuming the catalyst. A similar phenomenon has been discovered in quantum information science, where physical transformations become possible by utilizing a quantum degree of freedom that returns to its initial state at the end of the process. In this review, a comprehensive overview of the concept of catalysis in quantum information science is presented and its applications in various physical contexts are discussed.

Knowing the physicochemical properties of exhaled droplets and aerosol particles is a prerequisite for a detailed mechanistic understanding and effective prevention of the airborne transmission of infectious human diseases. This review provides a critical consideration and synthesis of scientific knowledge on the number concentrations, size distributions, composition, mixing state, and related properties of respiratory particles emitted upon breathing, speaking, singing, coughing, and sneezing. A parametrization of respiratory particle size distributions is derived and presented based on five log-normal modes related to different origins in the respiratory tract, which can be used to trace and localize the sources of infectious particles. This approach may support the medical treatment as well as the risk assessment for aerosol and droplet transmission of infectious diseases. It was applied to analyze which respiratory activities may drive the spread of specific pathogens, such as Mycobacterium tuberculosis, influenza viruses, and severe acute respiratory syndrome coronaviruses 2 (SARS-CoV-2). The results confirm the high relevance of vocalization for the transmission of SARS-CoV-2, as well as the usefulness of physical distancing, face masks, room ventilation, and air filtration as preventative measures against coronavirus disease 2019 and other airborne infectious diseases.

Innovations in fluid mechanics have been leading to better food since ancient history, while creativity in cooking has inspired fundamental breakthroughs in science. This review addresses how recent advances in hydrodynamics are changing food science and the culinary arts and, reciprocally, how the surprising phenomena that arise in the kitchen are leading to new discoveries across the disciplines, including molecular gastronomy, rheology, soft matter, biophysics, medicine, and nanotechnology. This review is structured like a menu, where each course highlights different aspects of culinary fluid mechanics. Our main themes include multiphase flows, complex fluids, thermal convection, hydrodynamic instabilities, viscous flows, granular matter, porous media, percolation, chaotic advection, interfacial phenomena, and turbulence. For every topic, an introduction and its connections to food are provided, followed by a discussion of how science could be made more accessible and inclusive. The state-of-the-art knowledge is then assessed, the open problems, along with the likely directions for future research and indeed future dishes. New ideas in science and gastronomy are growing rapidly side by side.

Quantum theory has been successfully validated in numerous laboratory experiments. But would such a theory, which effectively describes the behavior of microscopic physical systems and its predicted phenomena such as quantum entanglement, still be applicable on large length scales? From a practical perspective, how can quantum key distribution (where the security of establishing secret keys between distant parties is ensured by the laws of quantum mechanics) be made technologically useful on a global scale? Owing to photon loss in optical fibers and terrestrial free space, the achievable distance using direct transmission of single photons has been limited to a few hundred kilometers. A promising route to testing quantum physics over long distances and in the relativistic regimes, and thus realizing flexible global-scale quantum networks, is via the use of satellites and space-based technologies, where a significant advantage is that the photon loss and turbulence predominantly occurs in the lower $\sim 10\mathrm{km}$ of the atmosphere, and most of the photons’ transmission path in space is virtually in vacuum, with almost zero absorption and decoherence. Progress in free-space quantum experiments, with a focus on the fast-developing Micius satellite–based quantum communications, is reviewed. The perspective of space-ground integrated quantum networks and fundamental quantum optics experiments in space conceivable with satellites are discussed.

Yearslong time series of high-precision brightness measurements have been assembled for thousands of stars with telescopes operating in space. Such data have allowed astronomers to measure the physics of stellar interiors via nonradial oscillations, opening a new avenue to study the stars in the Universe. Asteroseismology, the interpretation of the characteristics of oscillation modes in terms of the physical properties of the stellar interior, brought entirely new insights in how stars rotate and how they build up their chemistry throughout their evolution. Data-driven space asteroseismology has delivered a drastic increase in the reliability of computer models mimicking the evolution of stars born with a variety of masses and metallicities. Such models are critical ingredients for modern physics as a whole because they are used throughout various contemporary and multidisciplinary research fields in space science, including the search for life outside the Solar System, archaeological studies of the Milky Way, and the study of single and binary supernova progenitors, among which are future gravitational wave sources. The specific role and potential of asteroseismology for those modern research fields are illustrated. The review concludes with current limitations of asteroseismology and highlights how they can be overcome with ongoing and future large infrastructures for survey astronomy combined with new theoretical research in the era of high-performance computing. This review presents results obtained through major community efforts over the past decade. These breakthroughs were achieved in a collaborative and inclusive spirit that is characteristic of the asteroseismology community. The review’s aim is to make this research field accessible to graduate students and readers coming from other fields of physics, with incentives to enjoy and join future applications in this domain of astrophysics.

The climate is a forced, dissipative, nonlinear, complex, and heterogeneous system that is out of thermodynamic equilibrium. The system exhibits natural variability on many scales of motion, in time as well as space, and it is subject to various external forcings, natural as well as anthropogenic. This review covers the observational evidence on climate phenomena and the governing equations of planetary-scale flow and presents the key concept of a hierarchy of models for use in the climate sciences. Recent advances in the application of dynamical systems theory, on the one hand, and nonequilibrium statistical physics, on the other hand, are brought together for the first time and shown to complement each other in helping understand and predict the system’s behavior. These complementary points of view permit a self-consistent handling of subgrid-scale phenomena as stochastic processes, as well as a unified handling of natural climate variability and forced climate change, along with a treatment of the crucial issues of climate sensitivity, response, and predictability.

The observation of metallic ground states in a variety of two-dimensional electronic systems poses a fundamental challenge for the theory of electron fluids. Here evidence is analyzed for the existence of a regime, called the “anomalous metal regime,” in diverse 2D superconducting systems driven through a quantum superconductor to metal transition by tuning physical parameters such as the magnetic field, the gate voltage in the case of systems with a metal-oxide semiconductor field-effect transistor (MOSFET) geometry, or the degree of disorder. The principal phenomenological observation is that in the anomalous metal, as a function of decreasing temperature, the resistivity first drops as if the system were approaching a superconducting ground state, but then saturates at low temperatures to a value that can be orders of magnitude smaller than the Drude value. The anomalous metal also shows a giant positive magnetoresistance. Thus, it behaves as if it were a “failed superconductor.” This behavior is observed in a broad range of parameters. It will be moreover exhibited, by theoretical solution of a model of superconducting grains embedded in a metallic matrix, that as a matter of principle such anomalous metallic behavior can occur in the neighborhood of a quantum superconductor to metal transition. However, it will be also argued that the robustness and ubiquitous nature of the observed phenomena are difficult to reconcile with any existing theoretical treatment and speculate about the character of a more fundamental theoretical framework.