The most popular Physics Today stories of 2024

The list below highlights some of the most read articles published this year in Physics Today.

Why woodpeckers don’t get concussions, January, page 54.
With each powerful strike into the bark of a tree, woodpeckers subject their brains to decelerations of up to 400 g—about three times the threshold that would give a person a concussion. Sam Van Wassenbergh and Maja Mielke describe the relatively simple physics that keeps the birds’ brains unscathed and debunk a common misconception about woodpecker anatomy. Their explainer was the most read story on Physics Today‘s website this year.

Nobel Prize highlights neural networks’ physics roots , December, page 12.
Artificial intelligence is undoubtedly making a major impact on physics, and physicists have been major contributors to the development of AI. Nonetheless, the awarding of the 2024 Nobel Prize in Physics to AI pioneers John Hopfield and Geoffrey Hinton caught many observers by surprise. Physics Today‘s announcement day report by Laura Fattaruso and follow-up deeper dive by Johanna Miller explain how Hopfield, Hinton, and others applied physics-based thinking to develop the brain-inspired information processing that underlies today’s machine-learning and AI marvels.

Fixing the PhD qualifying exam , July, page 34.
“When questioning the rationale behind the qualifying process, we find that the arguments for retaining the traditional qualifying exam’s written and oral components do not hold up to scrutiny,” write climate dynamics professors Tim DelSole and Paul Dirmeyer. For the past five years, their department at George Mason University has used a different evaluation process. DelSole and Dirmeyer describe the new approach and its goal of elevating the qualifying process “from a routine student assessment to a shared journey of scientific discovery.”

Slow-motion spectroscopy paves the way for a nuclear clock , June, page 12.
The ticks of an atomic clock are tied to the frequency of an electronic transition between energy levels. Atomic nuclei can also shift between discrete energy states, but almost all those transitions occur at very high energies. The only known exception is a transition in the radioactive nuclide thorium-229. Earlier this year, after a long pursuit, two groups of researchers succeeded in exciting a ²²⁹Th nucleus with a laser, Physics Today‘s Johanna Miller reports. The work is a key advance toward the development of a nuclear clock, which could enable tests of fundamental physics with more precision than even the best atomic clocks can achieve. The next step is to home in on the frequency more precisely—and progress has already been made .

Translating scientific papers for the public , 18 December 2023 online, February 2024, page 52 .
Eager to make your research more accessible without glossing over all the effort that has gone into your work? Cosmologist and science communicator Claire Lamman creates what she calls doodle summaries, marking up her peer-reviewed publications with text, drawings, and other annotations aimed at her desired audience. To demonstrate the format for Physics Today readers, she annotates the 1998 Astronomical Journal paper by Adam Riess and colleagues that demonstrated that the expansion of the universe is accelerating.

The high-profile contest to explain Einstein , 12 April online.
Here’s a challenge: Write an essay of no more than 3000 words to explain Albert Einstein’s theories of relativity. In 1920, just a year after the famous solar eclipse expedition to confirm general relativity, Scientific American sponsored a contest for its readers with that charge. Willem de Sitter, Henry Norris Russell, and other prominent scientists vied for the $5000 prize. Fittingly, as Physics Today‘s Ryan Dahn recounts, they lost to a patent examiner.

The new laser weapons , January, page 32.
Military lasers may bring to mind the Star Wars era of the 1980s and 1990s. Yet laser technology has come a long way since then, and the US and other countries are pursuing the development of high-energy lasers and other directed-energy weapons. Tom Karr and Jim Trebes, both former principal directors for directed energy at the US Department of Defense, outline the new technologies and their potential strategic value as a tactical safeguard against drones and cruise missiles.

Where the atomic nuclei are: Maurice Sendak, physics illustrator , November, page 38.
The first credited work of famed children’s author and illustrator Maurice Sendak appeared in … a physics book? Coauthored by his high school physics teacher, Atomics for the Millions (1947) demystified nuclear science for laypeople with the aid of drawings, cartoons, and diagrams by the teenage Sendak. A major theme of both the book and Sendak’s illustrations, explains Physics Today‘s Ryan Dahn, was the “binary choice between nuclear utopia and nuclear oblivion that the authors believed humanity was facing” in the wake of the Hiroshima and Nagasaki bombings.

State anti-DEI laws sow uncertainty in public colleges and universities , April, page 22.
In recent years, Florida, Texas, Utah, and other states have passed legislation that bans many diversity, equity, and inclusion (DEI) activities in their public institutions of higher education. Physics Today‘s Toni Feder talked to physics professors and university administrators to gauge the effects of the new laws on efforts to support students and faculty from underrepresented groups and increase diversity in the field. “The laws are sending a chill across campuses, with uncertainty about what is legal and what the consequences are for individuals or institutions that overstep,” Feder writes.

The real butterfly effect and maggoty apples , May, page 30.
Weather forecasting models are steadily improving. Climate physicist Tim Palmer presents an intriguing question: Is there a limit to how far in the future such models can accurately predict? His answer guides readers through Edward Lorenz’s original proposal of the butterfly effect, the Navier–Stokes equations of fluid mechanics, and, as promised in the headline, maggot-laden fruit. “In short,” he writes, “taking a rigorous approach to the science of uncertainty can help us improve our ability to both predict and understand our very chaotic world.”