The 50 most-cited articles in Physics Today, 2021

Although the question is a classical problem, the details of how wind transfers energy to waves at the ocean surface remain elusive.

Even in the absence of light, coupling cavities with molecules and materials can modify their chemical reactivity, conductivity, and more.

First envisioned for elucidating crystalline structures, the technique is now used for high-resolution lensless imaging, wavefront sensing, and more.

In many kinds of irregular media, propagating waves enter a beautiful and relatively neglected regime called branched flow. It affects sound, light, water, and matter waves over vastly different length scales.

This Physics Today article discusses why the physics community needs to embrace the challenge of educating students with diverse educational backgrounds to meet future research and workforce demands and outlines some of the efforts underway.

Caused by simple fluctuations in space, the Casimir effect may validate theories of the cosmological constant and allow for measurements of ultrasmall magnetic fields.

Although a liquid’s viscosity depends strongly on temperature and pressure, its minimum value is fixed by fundamental physical constants.

Emerging applications and studies utilize gallium-based alloys for their unique properties.

A newly discovered mechanism can help keep the world’s fastest jets from overheating.

Research into dual-process theories of reasoning from cognitive psychology suggests ways to improve classroom instruction in physics.

The contradictory implications of statistical mechanics have worried physicists and philosophers for centuries. Does our present-day knowledge allow us to exorcize those philosophical demons?

By integrating artificial intelligence algorithms and physics-based simulations, researchers are developing new models that are both reliable and interpretable.

Although the US has sufficient raw materials, the domestic supply chain to alloy and manufacture rare-earth permanent magnets is almost nonexistent.

Spectacular collective phenomena, such as jamming, turbulence, wetting, and waves, emerge when living cells migrate in groups.

Interdisciplinary teams that integrate theory, data, and computing can now produce urgently needed, action-oriented climate science.

Modern high-performance CT scanners are unparalleled among three-dimensional imaging systems in data acquisition speed and spatial resolution.

One-photon and two-photon interferences have recently led researchers to develop new classes of quantum cryptographic protocols.

Integrated quantum-control protocols could bridge the gap between abstract algorithms and the physical manipulation of imperfect hardware.

The behavior of extremely dim galaxies provides stringent constraints on the nature of dark matter. Establishing those constraints depends on precise stellar-motion measurements.

Computer models can now provide stunningly accurate predictions of proteins’ three-dimensional structures. But what about their biological functions?

Liquid droplets act as microreactors. Can they also serve as a control mechanism for cellular biochemistry?

Unexploited lithium deposits lie throughout the world, but investment in new mines is lagging.

Classical chaos gains some additional degrees of freedom in materials with excitations described by the Dirac equation.

Scientists can help by partnering with museums, out-of-school programs, schools, organizations that develop instructional materials, or other educational projects.

The limits of nuclear stability provide deep insights into the fundamental force responsible for the presence of matter.

Although targeted actuation of neurons via magnetic fields may benefit neuroscience research and medicine, some approaches have sparked controversy.

An international collaboration aims to couple ultrafast lasers with integrated photonics to create chip-scale devices.

As a photoexcited molecule breaks apart, we can see not just where the fragments are but also whether they are departing from the beaten path.

Meteorological practices that developed in the first millennium did not die in the Middle Ages but were radically improved with an international science of weather forecasting.

How can researchers geometrically tune the extent to which a material embodies a stiff or flexible structure?

The Department of Energy has lowered its 2030 targets for the price of energy from photovoltaics and concentrated solar power. But the low-hanging fruits have been picked.

Physics and astronomy communities take a page from data-science and tech worlds to hold events of feverish teamwork.

Collaborations enrich science communication, visualization, and inspiration.

Fluid turbulence generates a chaotic soup of strongly nonlinear features that are hard to mathematically describe and model. A recent theoretical simplification brings fresh insight.

The past four years saw interference in the scientific process, inaction on climate change, and a weakened federal science workforce. Artificial intelligence and quantum information science benefited.

Although the Canadian and US nuclear industries have shared origins in World War II, their paths soon diverged.

Your typical commute hides complex fluid-dynamical pathways of disease transmission. Where you sit and the windows you open could heighten or suppress the risk of airborne infection.

A career in technology transfer requires skills in multitasking, communicating, and negotiating; one reward is seeing scientific advances benefit society.

Photographs of aboveground and underground structural failures after earthquakes uncover simple but not widely recognized physics.

The frozen continent’s ice shelves are melting. Where is the water going, and what does it mean for the future?

The medical industry is substituting x-ray sources for cesium-based blood irradiators. Other industries are also exploring alternative technologies.

One of the pioneers of radioactivity research, Rutherford feared his work would be overlooked—and changed his publishing strategies to make sure it wasn’t.

More than a year into the COVID-19 pandemic, researchers seek alternative targets to the spike protein, whose rapid mutations threaten the effectiveness of current vaccines.

The beloved after-school show of the 1980s was the product of a then revolutionary idea: asking children what they wanted in a television science series.

The hues of blue birds come from constructive interference, but scattering and refraction also matter.