In a lab in Illinois, physicists captured and tamed a tiny particle of antimatter in a trap with invisible walls. By studying how the positron behaved, the researchers may soon have a chance to break our best mathematical model of physical reality.

The positron is the antimatter counterpart of the electron, which means the two particles have the same mass but the opposite electric charge. Unlike electrons, however, positrons are rare and typically exist for a tiny fraction of a second because the moment one meets one of the super-abundant electrons in our universe, the pair annihilate. This makes positrons difficult to study.

at Northwestern University in Illinois and his colleagues have now found a way to trap a positron and keep it around for months on end. By analysing data collected while the positron was trapped, they plan to precisely measure the antiparticle’s properties and consequently investigate one of the biggest problems with the standard model of particle physics.

The researchers obtained the positron from a radioactive isotope of sodium that emits one whenever it decays. Such positrons are very fast and hard to control, so they placed the sodium into a special refrigerator to lower its temperature and energy, and slow down the antiparticles.

They slowed them further by directing the positrons through a tungsten crystal. While some positrons were annihilated as they travelled through the crystal, some came through unscathed. They were then directed into a refrigerated chamber that was empty of all other particles. Here, electronic components generated electromagnetic fields that confined a single incoming positron, serving as invisible walls that trapped the particle.

The researchers then pushed the positron into its lowest possible energy state, which Gabrielse says allowed them to keep the otherwise elusive antiparticle trapped for months. They could also push it into the next lowest energy state with controlled bursts of microwaves.

Subscriber-only newsletter

Sign up to Editor’s Highlights

Sign up to newsletter

“It’s a real kick to stand in my lab and watch a positron making transitions – ‘quantum jumps’ we call them – between its lowest energy states. How much more fundamental, how much neater can it get?” he says.

“Trapping an antiparticle is extremely difficult,” says at Japanese scientific institute RIKEN, particularly since any stray particle, burst of light or tiny vibration could disturb it and the trap had to be kept just tenths of a degree above the coldest temperature possible.

The payoff for trapping and controlling the positron despite these experimental challenges could be remarkable. “This has the potential to become one of the most precise measurements of a fundamental constant in physics,” says Ulmer.

Six ways we could finally find new physics beyond the standard model

Leading physicists explain how they think we will discover the new particles or forces that would complete one of science’s greatest unfinished masterpieces

Specifically, Gabrielse and his colleagues want to measure the positron’s magnetic moment, which is a number that quantifies its response to magnetic fields. The researchers have previously made the most precise ever measurement of the electron’s magnetic moment, and comparing this figure with the one for the antiparticle would enable them to compare the properties of matter and antimatter with unprecedented precision.

The standard model predicts they should have identical magnetic moments, but this prediction underscores a notable shortcoming of this theory. The problem is that if matter and antimatter are so alike, then they should have been created in equal amounts and fully annihilated as the universe began, leaving nothing. “The standard model seems to be inconsistent, or at least significantly incomplete, with basic features of the universe, like why we have a universe at all,” says Gabrielse.

Uncovering a difference between the electron and positron could hint at some currently unknown mechanism that resulted in our matter-filled universe. If all goes according to plan, the researchers aim to have data that will shed light on this within the year.

Leap seconds, previously used to keep the world’s clocks in sync with Earth’s rotation, are to be abolished. Instead, universal time will be allowed to drift up to an hour from astronomical time before it is corrected. Representatives from 69 countries voted for the change on 15 October at a meeting of the in Versailles, France.

As the gap between clock time and astronomical time slowly grows, the effect will eventually be “like living on daylight saving time”, but permanently, says , curator of time at the Royal Observatory in Greenwich, London.

For most of history, our clocks have been set by the apparent position of the sun in the sky. But in 1967, after the development of super-accurate atomic clocks, physicists defined an international time standard called coordinated universal time (UTC), based instead on the speed of a particular vibration of the caesium-133 atom.

Natural fluctuations in Earth’s rate of rotation meant periodic corrections were needed to keep universal time in sync with the sky. As the rotation slowed, physicists added extra leap seconds. Twenty-seven have been added to UTC since they were introduced in 1972.

Now, that strategy is to be abandoned. This is partly because technological systems, from stock markets to telecommunications to GPS, have become much more reliant on precise timekeeping. That means introducing leap seconds is more complex, potentially risking the failure of mobile phone networks or electricity grids. Previous leap seconds have caused websites to crash and disrupted airlines’ booking systems, says at the National Physical Laboratory (NPL) in Teddington, UK.

“Time is now so much more important and integrated into these systems,” says Akkermans. “What once worked has become more problematic.”

Subscriber-only newsletter

Sign up to Editor’s Highlights

Sign up to newsletter

What’s more, Earth’s rotation has recently begun to accelerate slightly, raising the daunting possibility of needing “a first-ever negative leap second”, said , who heads the BIPM’s committee on time and frequency, in a statement. The practical consequences of such a jump backwards in time are hard to predict.

Physicists have been debating what to replace the leap second with for the past 30 years. At the BIPM meeting, they finally voted for a “leap hour”, which means that UTC will be allowed to diverge from astronomical time for up to an hour before being corrected. That should ensure an uninterrupted flow of time for “several centuries”, said Dimarcq. The change will take effect from 20 May 2027.

Time crystals could be used to build accurate quantum clocks

Once considered an oddity of quantum physics, time crystals could be a good building block for accurate clocks and sensors, according to new calculations

Shemar emphasises that the effects involved are very small: “It’ll be many hundreds or even thousands of years before a leap hour is needed.” He adds that physicists will still be accurately tracking Earth’s rotation to provide information for astronomy and celestial navigation.

The leap hour isn’t the only temporal innovation being planned, though. The BIPM meeting also asked for proposals on a new definition of the second – needed because optical clocks are now much more accurate than the caesium clock that time is currently based on – and called on international agencies to start considering how to define a universal time standard for the moon. Overall, the changes “will have a profound impact on future timekeeping both on Earth and other planets”, said Dimarcq.

The hall hummed with joyous curiosity at this year’s New Scientist Live at Excel London, which ran from 10 to 12 October and attracted thousands of visitors of all ages.

With topics including the search for extraterrestrial life, what AI is teaching us about consciousness and the maths behind Pokémon, there was a delightful range to explore. Highlights included physicist Jim Al-Khalili diving into the deepest mysteries of time and psychologist Kimberley Wilson on how to build lifelong brain health. Other packed talks ranged from how we evolved, from anthropologist Alice Roberts, to a myth-busting take on supplements by doctors Chris and Xand van Tulleken.

Fans lined up to meet speakers, including naturalist Chris Packham, who shared moving thoughts on why science is crucial to tackling the climate crisis. Younger fans flocked for selfies with mathematician and YouTuber Tom Crawford, who fought a fierce maths battle with maths teacher and TV presenter Bobby Seagull.

On the show floor, people could journey through a giant inflatable gut, 3D-print organs and get hands-on with large insects. They also lined up to board a Chinook helicopter, or step into a hospital of the future. Plus, in virtual reality, they could swim through coral reefs and explore the body in 3D.

Visitors also saw New Scientist staff, including editor Catherine de Lange, predict the biggest scientific breakthroughs in the next 70 years. Plus, podcast editor Rowan Hooper hosted an emergency briefing on the climate crisis, joined by leading climate and biodiversity scientists.

The talks were all recorded and will be available to stream online for 12 months. See for details of how to get access.

at the University of Wisconsin–Madison has won the 2026 Nobel prize in physics for his work on spotting ghostly particles called neutrinos using a detector at the South Pole.

Neutrinos are subatomic particles that rarely interact with material, are electrically neutral and perfuse the whole universe. Because of this, we can detect neutrinos that originated far away in the cosmos, trace their origin and learn more about the nature of the universe. Cosmic neutrinos are produced when a proton collides with another particle.

If you hold your hand out flat, more than a billion neutrinos will pass through it every second. These originate from the sun, but Halzen’s work concerns the much more rare and high-energy neutrinos coming from deep within the cosmos and what their detection can tell us about the universe.

Neutrinos act like “ghost-like messengers from the cosmos”, said , chair of the Nobel committee for physics, at a press conference. “It’s a way of bringing us information about distant cosmic sources which we’re unable to acquire in other ways.”

In 1988, Halzen proposed using the Antarctic ice as a neutrino detector, then went on to spearhead an international collaboration of more than 450 people from 58 institutions in 14 countries to make the IceCube Neutrino Observatory a reality.

The detector uses thousands of light sensors buried 2 kilometres under the surface of the ice in deep holes drilled using hot water. As neutrinos shoot through Earth, they interact with the ice, creating what’s known as Cherenkov radiation and emitting blue light. The network of light sensors allows researchers to trace their trajectory back to their origin point, revealing vital information about their formation.

Subscriber-only newsletter

Sign up to Lost in Space-Time

Sign up to newsletter

Halzen calculated that, if you built a neutrino collector 1 cubic kilometre in size, you would detect one neutrino per day. IceCube was completed in 2010 and began full operations the following year. The first high-energy extraterrestrial neutrinos were detected in 2013.

“When I reflect on this moment, I have to emphasise how lucky I was,” said Halzen, addressing the press conference by phone. “Because when we started this project, everybody realised this was maybe a good idea, but very few thought it would work – including myself. So this was kind of an adventure where success was not guaranteed, and we were lucky to overcome the various challenges. It was a long journey, but finally it worked.”

Halzen said he hopes the prize will reflect on the collaborators who worked on the project in the early days.

The IceCube detector has gone on to make many more discoveries. In 2017, it helped identify the first definitive source for a single high-energy cosmic neutrino: a blazar called TXS 0506+056 that blasted a huge jet of energy towards Earth. In 2023, it identified neutrinos from within our own galaxy, the Milky Way, which are typically overwhelmed by stronger signals from the rest of the universe.

Of winning the award, Halzen said: “It was a great surprise and I didn’t expect it. It’s a great pleasure.”