Featured
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News & Views |
Protons on the line
Stable regions in four-dimensional phase space have been observed by following the motion of accelerated proton beams subject to nonlinear forces. This provides insights into the physics of dynamical systems and may lead to improved accelerator designs.
- Giulio Stancari
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Article
| Open AccessObservation of fixed lines induced by a nonlinear resonance in the CERN Super Proton Synchrotron
Nonlinear resonances can cause particle loss in accelerators. Experiments confirm that a coupled nonlinear resonance traps beam particles on a four-dimensional closed curve. This finding allows the development of mitigation strategies.
- H. Bartosik
- , G. Franchetti
- & F. Schmidt
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Comment |
A physics curriculum for the modern world
Increasingly, physics graduates take jobs outside academia. Active teaching approaches lead to deeper conceptual understanding and a more varied skill set and are therefore more likely to prepare students for successful careers.
- Jenaro Guisasola
- & Kristina Zuza
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Perspective |
Epistemic agency as a critical mediator of physics learning
Encouraging students to take ownership of their learning can improve their outcomes. This Perspective discusses ways to achieve this in the context of physics education and how digital technology can help Gen Z students in particular.
- Nam-Hwa Kang
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Review Article |
Towards meaningful diversity, equity and inclusion in physics learning environments
Women and ethnic and racial minority students are underrepresented in physics. This Review summarizes research on equity and inclusion in physics education and makes recommendations for making physics learning environments more equitable.
- Alexandru Maries
- & Chandralekha Singh
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World View |
Artificial intelligence needs a scientific method-driven reset
AI needs to develop more solid assumptions, falsifiable hypotheses, and rigorous experimentation.
- Luís A. Nunes Amaral
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News & Views |
Breaking fast and slow
When cracks creep forward in our three-dimensional world, they do so because of accompanying cracks racing perpendicular to the main direction of motion with almost sonic speed. Clever experiments have now directly demonstrated this phenomenon.
- Michael Marder
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Article
| Open AccessPropagation of extended fractures by local nucleation and rapid transverse expansion of crack-front distortion
Understanding the three-dimensional nature of fracture formation and dynamics is challenging. Experiments now show that a fracture front, after originating at a particular locus in a material, propagates jump-wise and expands transversely at high speed.
- T. Cochard
- , I. Svetlizky
- & D. A. Weitz
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Comment |
Dependency of ERC-funded research on US collaborations
Annually, the European Research Council (ERC) and the National Science Foundation (NSF) allocate resources to promote research excellence in Europe and the USA. We observe that European Union (EU)-based researchers rely strongly on United States (US) collaborations to secure top EU funding, while the reverse is much less common.
- Sandeep Chowdhary
- , Nicolò Defenu
- & Federico Battiston
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Article
| Open AccessUnconventional colloidal aggregation in chiral bacterial baths
Colloidal aggregates are conventionally formed by particle aggregation under thermal fluctuation. Now the structure and mechanical properties of aggregates can be controlled by an active bath of swimming Escherichia coli.
- Daniel Grober
- , Ivan Palaia
- & Jérémie Palacci
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Research Briefing |
Momentum cooling can improve transmission rates for proton therapy
Using ‘momentum cooling’ in cyclotron-based proton therapy can increase proton transmission rates and thereby reduce treatment delivery times. This simple technique, which reduces the momentum spread of the proton beam without introducing substantial beam losses, enhances efficiency and has the potential to reduce costs, thereby advancing cancer treatment and improving patient outcomes.
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Article
| Open AccessDemonstration of momentum cooling to enhance the potential of cancer treatment with proton therapy
In cyclotron-based proton therapy facilities, beam loss due to large momentum spread can limit ultrahigh dose rates. Now, beam transmission is enhanced and higher dose rate is achieved by introducing momentum cooling through a wedge.
- Vivek Maradia
- , David Meer
- & Serena Psoroulas
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Article |
Creation of an isolated turbulent blob fed by vortex rings
Turbulence is generated in a quiescent environment using vortex rings as building blocks.
- Takumi Matsuzawa
- , Noah P. Mitchell
- & William T. M. Irvine
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Article
| Open AccessPhotonic metamaterial analogue of a continuous time crystal
So far, a continuous time crystal has only been implemented on a quantum system. Optically driven many-body interactions in a nanomechanical photonic metamaterial now allow the realization of a classical continuous time crystal.
- Tongjun Liu
- , Jun-Yu Ou
- & Nikolay I. Zheludev
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Article
| Open AccessScaling and intermittency in turbulent flows of elastoviscoplastic fluids
Elastoviscoplastic fluids combine solid- and liquid-like behaviour depending on applied stress. Simulations of elastoviscoplastic fluids at high Reynolds number now show that plasticity plays a key role in the turbulent flows seen in these systems, leading for example to intermittency.
- Mohamed S. Abdelgawad
- , Ianto Cannon
- & Marco E. Rosti
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Letter
| Open AccessFreezing-induced wetting transitions on superhydrophobic surfaces
Icephobic surfaces are helpful for increasing safety and sustainability in engineering applications. A study of the behaviour of supercooled droplets freezing on superhydrophobic surfaces now provides insights into ice-repellency mechanisms.
- Henry Lambley
- , Gustav Graeber
- & Dimos Poulikakos
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Comment |
How to restore trust in science through education
The authority of science within society is contested by antiscientific movements. To restore trust, science education should involve students in the social processes of knowledge production.
- P. Riccardi
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News & Views |
A route to greener Big Science
By recovering energy from a relativistically accelerated electron beam in a multiturn configuration, a reduction of radiofrequency power has been demonstrated. This is a milestone toward more efficient and better performing accelerators.
- Peter Williams
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Article |
Realization of a multi-turn energy recovery accelerator
By combining energy recovery technology and a multi-turn accelerating scheme in a linear accelerator, high-power beams can be achieved with considerably reduced energy consumption.
- Felix Schliessmann
- , Michaela Arnold
- & Simon Weih
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Article |
On-demand directional microwave photon emission using waveguide quantum electrodynamics
Light could be used to carry quantum information in networks, but this requires methods to prepare and control individual photons. A superconducting circuit can controllably emit photons in either direction along a microwave waveguide.
- Bharath Kannan
- , Aziza Almanakly
- & William D. Oliver
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Article |
Higher-order organization of multivariate time series
Most temporal analyses of multivariate time series rely on pairwise statistics. A study combining network theory and topological data analysis now shows how to characterize the dynamics of signals at all orders of interactions in real-world data.
- Andrea Santoro
- , Federico Battiston
- & Enrico Amico
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Article |
Emergence of equilibrated liquid regions within the glass
The transition from a glassy to a liquid phase is normally assumed to take place cooperatively across the whole material. But now, experiments show that, under certain conditions, isolated regions of liquid can form in the glassy matrix first.
- Ana Vila-Costa
- , Marta Gonzalez-Silveira
- & Javier Rodriguez-Viejo
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Perspective |
Imaging and computing with disorder
Multiple scattering of light in complex and disordered media scrambles optical information. This Perspective showcases how this often detrimental physical mixing can be exploited to extract and process information for optical imaging and computing.
- Sylvain Gigan
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Article
| Open AccessTransition from sub-Rayleigh anticrack to supershear crack propagation in snow avalanches
Avalanches can occur when a porous snow layer lies beneath a dense cohesive snow slab. Field experiments and simulations now reveal different crack-propagation regimes in slab avalanches, similar to rupture propagation following an earthquake.
- Bertil Trottet
- , Ron Simenhois
- & Johan Gaume
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Comment |
Limits to economic growth
Across the world, decisions on investment and policy are made under the assumption of continuous economic expansion. Fundamental physical limits may soon put an end to this phase of development, as foreshadowed by the 1972 report The Limits to Growth.
- Thomas W. Murphy Jr
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News & Views |
Good vibrations
Originally suggested for the detection of gravitational waves, resonantly vibrating metal beams have been used in a recent laboratory experiment to measure Newton’s constant of gravitation and to verify Newton’s gravitational law.
- Christian Rothleitner
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Article |
Dynamic measurement of gravitational coupling between resonating beams in the hertz regime
Measurements of the gravitational interaction between two parallel beams vibrating in bending motion enable the quantitative investigation of dynamic gravitation in the hertz regime and allow the determination of the gravitational constant.
- Tobias Brack
- , Bernhard Zybach
- & Jürg Dual
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Measure for Measure |
The new kilogram for new technology
The shift of the definition of the kilogram in 2019 away from an artefact to one relying on the Planck constant inspires technological innovation, as Naoki Kuramoto elucidates.
- Naoki Kuramoto
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Measure for Measure |
The unit that shall not be named
Juris Meija takes a look at the tumultuous past of the atomic unit of mass from its beginnings as an idea to its most recent revisions in a hotel bar.
- Juris Meija
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Article |
Topological dissipation in a time-multiplexed photonic resonator network
Topological phenomena have mostly been studied in conservative systems. Experiments on optical resonator networks now show that topologically non-trivial characteristics can also emerge in dissipation.
- Christian Leefmans
- , Avik Dutt
- & Alireza Marandi
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News & Views |
Making weaves
Acoustic waveguides have been used to implement the long-theorized phenomenon of non-Abelian braiding, in which abstract geometric constructions are used to generate transformations between different modes.
- Yidong Chong
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Article |
Classical non-Abelian braiding of acoustic modes
Although it shows promise for applications, non-Abelian braiding is difficult to realize in electronic systems. Its demonstration using acoustic waveguides may provide a useful platform to study non-Abelian physics.
- Ze-Guo Chen
- , Ruo-Yang Zhang
- & Guancong Ma
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Editorial |
Round and round it goes
This month, we celebrate the discovery of electromagnetic rotation, the principle behind the electric motor.
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News & Views |
Non-local oddities
Introducing non-local effects to metamaterials increases the complexity of their dispersion relation, which allows carefully designed elastic structures to mimic the peculiar roton behaviour of correlated quantum superfluids.
- Romain Fleury
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Comment |
Best practice for instructional labs
Undergraduate labs are more effective and more positive for students if they encourage investigation and decision-making, not verification of textbook concepts.
- Emily M. Smith
- & N. G. Holmes
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Measure for Measure |
Political union through science
The metric system is one of the enduring achievements of the French Revolution. Martin Milton recounts how it was also intended to unite nations.
- Martin J. T. Milton
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Comment |
Muon colliders to expand frontiers of particle physics
Muon colliders offer enormous potential for the exploration of the particle physics frontier but are challenging to realize. A new international collaboration is forming to make such a muon collider a reality.
- K. R. Long
- , D. Lucchesi
- & V. Shiltsev
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Perspective |
Topology and broken Hermiticity
The interplay of topological properties and non-Hermitian symmetry breaking has been implemented for a range of classical-wave systems. Recent advances, challenges and opportunities are reviewed across the different physical platforms.
- Corentin Coulais
- , Romain Fleury
- & Jasper van Wezel
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Measure for Measure |
The sound of weights and measures
In first-century China, emperor Wang Mang standardized weights and measures in his newly established dynasty. Noa Hegesh tells the story of sound as the basis for this standardization.
- Noa Hegesh
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News & Views |
An acoustic black hole
An elegant experiment showing that acoustic waves are amplified after scattering by a rotating body demonstrates an effect predicted in 1971 by Yakov Zel’dovich. This result has implications for the understanding of scattering from black holes.
- Bruce W. Drinkwater
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Article |
Amplification of waves from a rotating body
Acoustic waves that carry orbital angular momentum are amplified as they pass through an absorbing disk when the rotation rate exceeds the frequency of the incident wave, thus providing an experimental demonstration of Zel’dovich amplification.
- Marion Cromb
- , Graham M. Gibson
- & Daniele Faccio
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Article |
Flexible filaments buckle into helicoidal shapes in strong compressional flows
A general mechanism through which elastic filaments suspended in a strong compressional flow buckle and spontaneously acquire a chiral helicoidal shape is uncovered and elucidated theoretically.
- Brato Chakrabarti
- , Yanan Liu
- & Anke Lindner
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Article |
Polar jets of swimming bacteria condensed by a patterned liquid crystal
The relationship between the dynamics and spatial order of active matter gives rise to a rich phenomenology that is not fully understood. A study of bacteria swimming in a patterned liquid crystalline environment is a case in point, and provides a way to streamline the chaotic movements of swimming bacteria into polar jets.
- Taras Turiv
- , Runa Koizumi
- & Oleg D. Lavrentovich