The Year in Physics

December 17, 2025Carlos Arrojo for Quanta MagazineSenior EditorDecember 17, 2025It in no way reflects my feelings toward Quanta staff writer Charlie Wood that my favorite moment of the year in physics happened when he got seasick this summer aboard a ferry full of physicists on the North Sea.Charlie and hundreds of the world’s top quantum researchers were en route to Helgoland, the island birthplace of quantum mechanics, for a historic conference to mark the theory’s centennial. In the hundred years since Werner Heisenberg successfully formulated quantum theory while scrambling over Helgoland’s rugged cliffsides, quantum mechanics has transformed the world. Yet physicists remain confused and divided over the theory’s meaning and what it implies about the nature of reality. Charlie’s rip-roaring account of the Helgoland conference surveys the tangled web of quantum interpretations that are in play.The heated debate got underway not long after the passengers embarked. “What do you mean, what do I mean?” one physicist yelled at another, as the boat pitched and rolled and Charlie’s queasiness set in.

Get Quanta Magazine delivered to your inbox DESI CollaborationThe biggest news this year in fundamental physics was also the biggest news last year. In April 2024, a map of the cosmos released by the Dark Energy Spectroscopic Instrument (DESI) hinted that dark energy, the repulsive agent that’s driving the expansion of space, has been weakening over time. It seemed too interesting to be true, but this March, DESI physicists returned to the podium with an even bigger cosmological map (15 million galaxies this time, rather than 6 million) and a stronger conclusion. “We are much more certain than last year that this is definitely a thing,” one DESI member told Quanta. The same month, a second effort, the Dark Energy Survey, also reported evidence that dark energy is losing steam.Dark energy is spread thinly throughout space, amounting to a few atoms’ worth of mass per cubic meter; it can be thought of as the energy of space itself. But where it comes from, and why it is so diffuse, no one can say. If dark energy’s density really is dropping from one gigayear to the next, that points to a totally different explanation than if it were holding steady.The 2025 results are still not statistically strong enough to constitute a discovery. More data is needed. Luckily, the Vera C. Rubin Observatory, a powerful new telescope in Chile that began operations this summer, will map the locations of 20 billion galaxies over the next decade. That ought to be enough for researchers to say for sure whether dark energy is varying or not. Quanta Magazine; source: JWST/NASA/ESA/CSA and Lukas FurtakSpeaking of flagship telescopes, the James Webb Space Telescope yielded a major discovery about the early universe. We could barely see anything from the first billion years until the Webb launched a few years ago. Since then, the telescope has spotted aptly named “little red dots” all over the infant cosmos. Now physicists have worked out the identity of one of the dots: It’s an enormous black hole weighing 50 million suns, sitting alone in the young universe, shrouded by the thinnest veil of gas.We’ve detected black holes before, but this “naked” one is unique. It singlehandedly upends notions about the young universe. Black holes were thought to have come along only after the formation of galaxies, once stars gravitationally collapsed into black holes that then merged and grew. But this newfound behemoth exists with no galaxy in sight. Perhaps a galaxy took shape around it later. How this naked black hole (and any others like it) formed in the early universe — and whether it might even be primordial, originating from the Big Bang itself — has yet to be determined. “It’s terribly exciting. It’s highly informative,” said one of the physicists who worked out its identity. Mark Belan/Quanta MagazineIn September, as part of How We Came To Know Earth, Quanta’s special issue on climate science, Zack Savitsky told the epic story of climate modeling: an account of humanity’s largely successful quest over the past 60 years to build a computer model of Earth in order to ask what the future holds.The answer is dire. But the achievement is awe-inspiring.Climate modeling essentially amounts to solving an enormous set of equations describing how fluids slosh around the globe. The process of figuring out how to do that — what to put in the model and what to leave out — serves as a synecdoche for science as a whole. Always, understanding comes from pinpointing the relevant factors and forgetting the rest, from compressing nature’s endless intricacies into a human-readable story about the universe. Señor Salme for Quanta MagazineWith all the attention on AI this year, it’s natural to wonder whether our purportedly clever new machine friends are helping with our headiest human pursuits. In July, Anil Ananthaswamy reported on the impact AI is having on physics so far. Notably, the computers seem to have a knack for concocting bizarre physics experiments — designs that humans wouldn’t think of, which nevertheless work.Another impact of AI is the growing use of chatbots to generate calculations and proofs that look legitimate but are gibberish. In June, I had trouble telling whether someone really had solved the Yang-Mills mass gap problem — a calculation pertaining to the strong force that’s so difficult, it comes with a $1 million reward — as claimed in a paper posted to the physics preprint site arxiv.org. They had not. The formulas in the paper were AI-generated claptrap, but the paper had slipped through arxiv.org’s automatic filters. “The rejected-submission rate has risen dramatically since 2023 and has continued spiking upward in recent months, all driven by AI slop from quasi-technical people,” site administrator and physicist Paul Ginsparg told me. This dreck, he said, “poses an existential threat to arxiv methodology.”“How could this genius, this Einstein of the mind, just vanish into obscurity?” Amanda Gefter asks in her deliciously compelling feature about Peter Putnam. A student of the great physicist John Wheeler who wound up working as a janitor, Putnam “really should be regarded as one of the great philosophers of the 20th century,” according to one physicist who worked with him. “Turing, Gödel, and Putnam — they’re three peas in a pod. But one of them isn’t recognized.”Gefter tracked down storage units full of Putnam’s papers and sought to get to the bottom of his “brain calculus” — a theory of the mind that science now seems to be catching up to, and which might potentially help explain and improve today’s powerful AI models. “I might have walked away,” Gefter writes, “if I hadn’t been struck with the same feeling that had taken hold of everyone else: that Putnam was actually onto something.”Quanta didn’t report many breakthroughs in condensed matter physics in 2025, but incremental progress remains steady in that vast subfield, which concerns solids and their dizzying variety of properties and behaviors. For a dose of coverage from elsewhere, read Savitsky’s feature article about “strange metals.” In certain crystalline materials, the strange-metal phase is a precursor to high-temperature superconductivity; many specialists suspect they’ll have to crack what electrons are doing in strange metals before they can hope to control superconductors. Several theories have been posited recently about this phase of matter. It seems that “electrons” might not be the relevant vocabulary. Savitsky quotes the late physicist Jan Zaanen, who said that when it comes to strange metals, “it cannot be emphasized enough how misleading the very idea of a particle is.”Senior EditorDecember 17, 2025 Get Quanta Magazine delivered to your inbox Get highlights of the most important news delivered to your email inbox Quanta Magazine moderates comments to facilitate an informed, substantive, civil conversation. Abusive, profane, self-promotional, misleading, incoherent or off-topic comments will be rejected. 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