Popularity isn’t everything. But it is something, so for the second year running, we’re finishing our trip around the Sun by looking back at the physics stories that got the most attention over the past 12 months. Here, in ascending order of popularity, are the 10 most-read stories published on the Physics World website in 2025.

10. Quantum on the brain

We’ve had quantum science on our minds all year long, courtesy of 2025 being UNESCO’s International Year of Quantum Science and Technology. But according to theoretical work by Partha Ghose and Dimitris Pinotsis, it’s possible that the internal workings of our brains could also literally be driven by quantum processes.

Though neurons are generally regarded as too big to display quantum effects, Ghose and Pinotsis established that the equations describing the classical physics of brain responses are mathematically equivalent to the equations describing quantum mechanics. They also derived a Schrödinger-like equation specifically for neurons. So if you’re struggling to wrap your head around complex quantum concepts, take heart: it’s possible that your brain is ahead of you.

9. Could an extra time dimension reconcile quantum entanglement with local causality?

Einstein famously disliked the idea of quantum entanglement, dismissing its effects as “spooky action at a distance”. But would he have liked the idea of an extra time dimension any better? We’re not sure he would, but that is the solution proposed by theoretical physicist Marco Pettini, who suggests that wavefunction collapse could propagate through a second time dimension. Pettini got the idea from discussions with the Nobel laureate Roger Penrose and from reading old papers by David Bohm, but not everyone is impressed by these distinguished intellectual antecedents. In this article, Bohm’s former student and frequent collaborator Jeffrey Bub went on the record to say he “wouldn’t put any money on” Pettini’s theory being correct. Ouch.

8. And now for something completely different

Continuing the theme of intriguing, blue-sky theoretical research, the eighth-most-read article of 2025 describes how two theoretical physicists, Kaden Hazzard and Zhiyuan Wang, proposed a new class of quasiparticles called paraparticles. Based on their calculations, these paraparticles exhibit quantum properties that are fundamentally different from those of bosons and fermions. Notably, paraparticles strikes a balance between the exclusivity of fermions and the clustering tendency of bosons, with up to two paraparticles allowed to occupy the same quantum state (rather than zero for fermions or infinitely many for bosons). But do they really exist? No-one knows yet, but Hazzard and Wang say that experimental studies of ultracold atoms could hold the answer.

7. Shining a light on obscure Nobel prizes

The list of early Nobel laureates in physics is full of famous names – Roentgen, Curie, Becquerel, Rayleigh and so on. But if you go down the list a little further, you’ll find that the 1908 prize went to a now mostly forgotten physicist by the name of Gabriel Lippmann, for a version of colour photography that almost nobody uses (though it’s rather beautiful, as the photo shows). This article tells the story of how and why this happened. A companion piece on the similarly obscure 1912 laureate, Gustaf Dalén, fell just outside this year’s top 10; if you’re a member of the Institute of Physics, you can read both of them together in the November issue of Physics World.

6. How to teach quantum physics to everyone

Why should physicists have all the fun of learning about the quantum world? This episode of the Physics World Weekly podcast focuses on the outreach work of Aleks Kissinger and Bob Coecke, who developed a picture-driven way of teaching quantum physics to a group of 15-17-year-old students. One of the students in the original pilot programme, Arjan Dhawan, is now studying mathematics at the University of Durham, and he joined his former mentors on the podcast to answer the crucial question: did it work?

5. A great physicist’s Nobel-prize-winning mistake

Niels Bohr had many good ideas in his long and distinguished career. But he also had a few that didn’t turn out so well, and this article by science writer Phil Ball focuses on one of them. Known as the Bohr-Kramers-Slater (BKS) theory, it was developed in 1923 with help from two of the assistants/students/acolytes who flocked to Bohr’s institute in Copenhagen. Several notable physicists hated it because it violated both causality and the conservation of energy, and within two years, experiments by Walther Boethe and Hans Geiger proved them right. The twist, though, is that Boethe went on to win a share of the 1954 Nobel Prize for Physics for this work – making Bohr surely one of the only scientists who won himself a Nobel Prize for his good ideas, and someone else a Nobel Prize for a bad one.

4. Reconciling the ideas of Einstein and Newton

Black holes are fascinating objects in their own right. Who doesn’t love the idea of matter-swallowing cosmic maws floating through the universe? For some theoretical physicists, though, they’re also a way of exploring – and even extending – Einstein’s general theory of relativity. This article describes how thinking about black hole collisions inspired Jiaxi Wu, Siddharth Boyeneni and Elias Most to develop a new formulation of general relativity that mirrors the equations that describe electromagnetic interactions. According to this formulation, general relativity behaves the same way as the gravitational described by Isaac Newton more than 300 years ago, with the “gravito-electric” field fading with the inverse square of distance.

3. A list of the century’s best Nobel Prizes for Physics – so far

“Best of” lists are a real win-win. If you agree with the author’s selections, you go away feeling confirmed in your mutual wisdom. If you disagree, you get to have a good old moan about how foolish the author was for forgetting your favourites or including something you deem unworthy. Either way, it’s a success – as this very popular list of the top 5 Nobel Prizes for Physics awarded since the year 2000 (as chosen by Physics World editor-in-chief Matin Durrani) demonstrates.

2. Building bridges between gravity and quantum information theory

We’re back to black holes again for the year’s second-most-read story, which focuses on a possible link between gravity and quantum information theory via the concept of entropy. Such a link could help explain the so-called black hole information paradox – the still-unresolved question of whether information that falls into a black hole is retained in some form or lost as the black hole evaporates via Hawking radiation. Fleshing out this connection could also shed light on quantum information theory itself, and the theorist who’s proposing it, Ginestra Bianconi, says that experimental measurements of the cosmological constant could one day verify or disprove it.

1. The simplest double-slit experiment

Back in 2002, readers of Physics World voted Thomas Young’s electron double-slit experiment “the most beautiful experiment in physics”. More than 20 years later, it continues to fascinate the physics community, as this, the most widely read article of any that Physics World published in 2025, shows.

Young’s original experiment demonstrated the wave-like nature of electrons by sending them through a pair of slits and showing that they create an interference pattern on a screen even when they pass through the slits one-by-one. In this modern update, physicists at the Massachusetts Institute of Technology (MIT), US, stripped this back to the barest possible bones.

Using two single atoms as the slits, they inferred the path of photons by measuring subtle changes in the atoms’ properties after photon scattering. Their results matched the predictions of quantum theory: interference fringes when they didn’t observe the photons’ path, and two bright spots when they did.

It’s an elegant result, and the fact that the MIT team performed the experiment specifically to celebrate the International Year of Quantum Science and Technology 2025 makes its popularity with Physics World readers especially gratifying.

So here’s to another year full of elegant experiments and the theories that inspire them. Long may they both continue, and thank you, as always, for taking the time to read about them.

The post Winning the popularity contest: the 10 most-read physics stories of 2025 appeared first on Physics World.

There’s only a few days left in the International Year of Quantum Science and Technology, but we’re still finding plenty to celebrate here at Physics World HQ thanks to a long list of groundbreaking work by quantum physicists in 2025. Here are a few of our favourite stories from the past 12 months.

Observing negative time in atom-photon interactions

By this point in 2025, “negative time” may sound like the answer to the question “How long have I got left to buy holiday presents for my loved ones?” Earlier in the year, though, physicists led by experimentalist Aephraim Steinberg of the University of Toronto, Canada and theorist Howard Wiseman of Griffith University in Australia showed that the concept can also describe the average amount of time a photon spends in an excited atomic state. While experts have cautioned against interpreting “negative time” too literally – we aren’t in time machine territory here – it does seem like there’s something interesting going on in this system of ultracold rubidium atoms.

Creating an operating system for quantum networks

It is a truth universally acknowledged that any sufficiently advanced technology must be in want of a simple system to operate it. In April, the quantum world passed this milestone thanks to Stephanie Wehner and colleagues at Delft University of Technology in the Netherlands. Their operating system is called QNodeOS, and they developed it with the aim of improving access to quantum computing for the 99.99999% percent of people who aren’t (and mostly don’t need to be) intimately familiar with how quantum information processors work. Another advantage of QNodeOS is that it makes it easier for classical and quantum machines (and quantum devices built with different qbit architectures) to communicate with each other.

Pushing the boundary between the quantum and classical worlds

How big does an object have to be before it stops being quantum and starts behaving like the billiard-ball-like solids familiar from introductory classical mechanics courses? It’s a question that featured in our annual “Breakthrough of the Year” back in 2021, when two independent teams demonstrated quantum entanglement in pairs of 10-micron drumheads, and we’re returning to it this year in a different system: levitated nanoparticles around 100 nm in diameter.

In one boundary-pushing experiment, Massimiliano Rossi and colleagues at ETH Zurich, Switzerland and the Institute of Photonic Sciences in Barcelona, Spain cooled silica nanoparticles enough to extend their wave-like behaviour to 73 pm. In another study, Kiyotaka Aikawa and colleagues at the University of Tokyo, Japan performed the first quantum mechanical squeezing on a nanoparticle, narrowing its velocity distribution at the expense of its momentum distribution. We may not know exactly where the quantum-classical boundary is yet, but the list of quantum behaviours we’ve observed in usually-not-quantum objects keeps getting longer.

Using a quantum computer to generate quantum random numbers

What’s the best way to generate random numbers? In part, the answer depends on how random those numbers really need to be. For many applications, the pseudorandom numbers generated by classical computers, or the random-but-with-systematic-biases numbers found in, say, radio static, are good enough. But if you really, really need those numbers to be random, you need a quantum source – and thanks to work published this year by Scott Aaronson, Shi-Han Hung, Marco Pistoia and colleagues, that quantum source can now be a quantum computer. Which is a neat way of tying things together, don’t you think?

Giving Schrödinger’s cats a nuclear option

Finally, we would be remiss not to mention the work of Andrea Morello and colleagues at the University of New South Wales, Australia. This year, they became the first to create quantum superpositions known as a Schrödinger’s cat states in a heavy atom, antimony, that has a large nuclear spin. They also created what is certainly the year’s best scientific team photo, posing with cats on their laps and deadpan expressions more usually associated with too-cool-for-school indie musicians.

So congratulations to them, and to all the other teams in this list, for setting the bar high in a year that offered plenty for the quantum community to celebrate. We hope you enjoyed the International Year of Quantum Science and Technology, and we look forward to many more exciting discoveries in 2026.

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This episode of the Physics World Weekly podcast features Pat Hanrahan, who studied nuclear engineering and biophysics before becoming a founding employee of Pixar Animation Studios. As well as winning three Academy Awards for his work on computer animation, Hanrahan won the Association for Computing Machinery’s A.M. Turing Award for his contributions to 3D computer graphics, or CGI.

Earlier this year, Hanrahan spoke to Physics World’s Margaret Harris at the Heidelberg Laureate Forum in Germany. He explains how he was introduced to computer graphics by his need to visualize the results of computer simulations of nervous systems. That initial interest led him to Pixar and his development of physically-based rendering, which uses the principles of physics to create realistic images.

Hanrahan explains that light interacts with different materials in very different ways, making detailed animations very challenging. Indeed, he says that creating realistic looking skin is particularly difficult – comparing it to the quest for a grand unified theory in physics.

He also talks about how having a background in physics has helped his career – citing his physicist’s knack for creating good models and then using them to solve problems.

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