• Comment |

    As the construction of the Electron–Ion Collider (EIC) is starting, the EIC Project Director Jim Yeck shares his experience on the main ingredients for success of big science projects.

    • Jim Yeck
  • Comment |

    Faced with an economic crisis as large and rapid as that precipitated by the COVID-19 pandemic, economists have turned to new ‘fast indicators’ based on big data, as Andy Haldane and Shiv Chowla of the Bank of England explain.

    • Andy Haldane
    •  & Shiv Chowla
  • Comment |

    János Kertész and Johannes Wachs discuss how complexity science and network science are particularly useful for identifying and describing the hidden traces of economic misbehaviour such as fraud and corruption.

    • János Kertész
    •  & Johannes Wachs
  • Comment |

    Caterina La Porta and Stefano Zapperi discuss how a suitable identification of the control and order parameters can shed light on the nature of phase transitions in cell migration.

    • Caterina A. M. La Porta
    •  & Stefano Zapperi
  • Comment |

    Mansi M. Kasliwal discusses the Global Relay of Observatories Watching Transients Happen (GROWTH) collaboration and shares her enthusiasm about the future of multi-messenger astrophysics.

    • Mansi M. Kasliwal
  • Comment |

    Alec Habig and Kate Scholberg describe the Supernova Early Warning System (SNEWS), an international network of neutrino detectors aimed to alert the astronomical community if supernova neutrinos are detected.

    • Alec Habig
    •  & Kate Scholberg
  • Comment |

    Sarah Antier describes the Global Rapid Advanced Network Devoted to the Multi-messenger Addicts (GRANDMA), which aims to identify and characterize the electromagnetic counterparts of gravitational wave sources

    • Sarah Antier
  • Comment |

    Why the Hall conductance is quantized was an open problem in condensed matter theory for much of the past 40 years. Spyridon Michalakis who worked on the solution — published in 2015 — gives a personal take on how the field evolved.

    • Spyridon Michalakis
  • Comment |

    Miguel Mostafa describes the Astrophysical Multimessenger Observatory Network (AMON), an online network that enables real-time coincidence searches using data from the leading multimessenger observatories and astronomical facilities.

    • Miguel Mostafá
  • Comment |

    The development of a new generation of detectors has been key to the success of X-ray free-electron lasers (XFELs). Anna Bergamaschi, Aldo Mozzanica and Bernd Schmitt discuss the advances in detector technology made over the past 10 years and examine the challenges presented by emerging high-repetition-rate XFEL facilities.

    • Anna Bergamaschi
    • , Aldo Mozzanica
    •  & Bernd Schmitt
  • Comment |

    The European XFEL is the first hard X-ray high-repetition-rate free-electron laser facility. Sakura Pascarelli, Serguei Molodtsov and Thomas Tschentscher, scientific directors of the European XFEL, discuss the challenges that lie ahead before the European XFEL can reach its full potential and cater for an international and diverse community of users.

    • Sakura Pascarelli
    • , Serguei Molodtsov
    •  & Thomas Tschentscher
  • Comment |

    The first decade of X-ray free-electron lasers (XFELs) has led to technological advances and scientific discoveries, but has also highlighted several facility-level challenges. Chi-Chang Kao, Director of SLAC, discusses the lessons to be learned from the first 10 years of operation and shares his thoughts on how facilities can overcome challenges facing XFEL development.

    • Chi-Chang Kao
  • Comment |

    X-ray free-electron lasers (XFELs) have rapidly developed into unique tools for probing diverse systems of interest to different scientific disciplines with angstrom–femtosecond resolution. Claudio Pellegrini provides an overview of the milestones in the development of XFELs and their unique capabilities.

    • Claudio Pellegrini
  • Comment |

    The rise of machine learning is moving research away from tightly controlled, theory-guided experiments towards an approach based on data-driven searches. Abbas Ourmazd describes how this change might profoundly affect our understanding and practice of physics.

    • Abbas Ourmazd
  • Comment |

    X-ray free-electron lasers (XFELs) are unique tools that are making possible time-resolved measurements of structural and electronic dynamics at the quantum spatial and temporal scales. Jonathan Marangos discusses the transformative scientific potential of this capability but also stresses the importance of lowering barriers to access to maximize scientific reach.

    • Jonathan P. Marangos
  • Comment |

    The rapid progress of atomic and nuclear physics in the twentieth century changed the way scientific results are documented, preserved and disseminated. Boris Pritychenko explains how atomic and nuclear data tables have become a central resource for the community.

    • Boris Pritychenko
  • Comment |

    Keeping track of the rapidly improving solar cell performance is not as easy as it seems. Martin Green describes the Solar Cell Efficiency Tables that have been providing regular updates of the record solar cell performance since the 1990s.

    • Martin A. Green
  • Comment |

    The increasing entropy of a black hole that evaporates by emitting Hawking radiation is at odds with the predictions of quantum mechanics. Juan Maldacena discusses the latest advances in solving this puzzle, known as the black hole information paradox.

    • Juan Maldacena
  • Comment |

    Knowing which atomic, molecular and optical physics computer code to use and how is a challenge. Andrew Brown surveys the available software packages and discusses how code development practices in academia could be improved.

    • Andrew Brown
  • Comment |

    The fluid mechanics of active materials, built around the idea of living systems as condensed matter made of free-energy-consuming particles, gives insight into biology and opens new directions in physics. Sriram Ramaswamy discusses the history and future of the field.

    • Sriram Ramaswamy
  • Comment |

    Insects have mastered flight to a degree that scientists are only now starting to comprehend. Itai Cohen and colleagues discuss some of the outstanding challenges and opportunities for studying this fascinating and beautiful behaviour.

    • Itai Cohen
    • , Samuel C. Whitehead
    •  & Tsevi Beatus
  • Comment |

    Each year millions of patients benefit from diagnostic services enabled by advances in medical imaging. However, some services rely on the supply of technetium-99m from an ageing nuclear infrastructure. Kevin Charlton discusses new technologies to secure a sustainable supply.

    • Kevin Charlton
  • Comment |

    Jose R. Alonso and colleagues describe technical advances that will allow the proposed IsoDAR (isotope decay at rest) cyclotron — being developed for neutrino physics research — to produce many medical isotopes more efficiently than existing cyclotrons can.

    • Jose R. Alonso
    • , Roger Barlow
    • , Janet M. Conrad
    •  & Loyd Hoyt Waites
  • Comment |

    In positron emission tomography, up to 40% of positron annihilation occurs through the production of positronium atoms in the patient’s body, whose decay could provide information about disease progression. New research is needed to take full advantage of this information.

    • Paweł Moskal
    • , Bożena Jasińska
    • , Ewa Ł. Stępień
    •  & Steven D. Bass
  • Comment |

    Despite much effort, the question of whether the Navier–Stokes equations allow solutions that develop singularities in finite time remains unresolved. Terence Tao discusses the problem, and possible routes to a solution.

    • Terence Tao
  • Comment |

    Data show that apart from their prize-winning work, the careers of Nobel laureates follow the same patterns as those of the majority of scientists.

    • Jichao Li
    • , Yian Yin
    • , Santo Fortunato
    •  & Dashun Wang
  • Comment |

    Oliver Brüning and Lucio Rossi discuss an upgrade of the Large Hadron Collider (LHC), the High-Luminosity LHC (HL-LHC), which aims to significantly increase the luminosity.

    • Oliver Brüning
    •  & Lucio Rossi
  • Comment |

    Steinar Stapnes discusses the Compact Linear Collider, a linear accelerator that could be built in three stages at CERN.

    • Steinar Stapnes
  • Comment |

    Edda Gschwendtner and Patric Muggli discuss the concept of plasma wakefield acceleration and its potential for future particle colliders and other applications.

    • Edda Gschwendtner
    •  & Patric Muggli
  • Comment |

    XinChou Lou describes the plans for the Circular Electron Positron Collider, a large accelerator complex that would be built in China.

    • XinChou Lou
  • Comment |

    Shinichiro Michizono describes the International Linear Collider, a proposed 250 GeV electron–positron collider using superconducting radiofrequency technology.

    • Shinichiro Michizono
  • Comment |

    Paul Howarth discusses the current challenges and opportunities in nuclear research and development.

    • Paul Howarth
  • Comment |

    Many small research reactors used as neutron sources are being shut down. To replace them, new facilities are being developed. In particular, compact accelerator-based neutron sources can take up many of the activities previously supported by reactor-based facilities.

    • John M. Carpenter
  • Comment |

    Gail Marcus discusses the current social, political and economic factors shaping the development of nuclear power worldwide.

    • Gail H. Marcus
  • Comment |

    Physics keeps changing and so do classification and subject indexing. Arthur Smith recalls the final updates to the Physics and Astronomy Classification Scheme (PACS) and the development of the Physics Subject Headings (PhySH), and ponders future directions.

    • Arthur Smith
  • Comment |

    Modern theoretical physics is indivisible. Ideas flow freely and fruitfully across traditional boundaries separating materials physics, fundamental physics and cosmology. How did this state of affairs come to be? What are its outstanding results? Is there more to come? Frank Wilczek discusses the synergy between the different fields of physics.

    • Frank Wilczek
  • Comment |

    The review article has a rich history and Roberto Lalli tells the story of how this scientific genre evolved in physics.

    • Roberto Lalli