CERN team solves decades-old mystery of light nuclei formation

13 Jan 2026

Light nuclei: Illustration of how deuterons can be produced from a high-energy collision. A delta particle emerging from the collision decays into a proton and a pion. The proton then undergoes nuclear fusion with a neutron to form a deuteron. (Courtesy: CERN)

When particle colliders smash particles together, the resulting debris cloud sometimes contains a puzzling ingredient: light atomic nuclei. Such nuclei have relatively low binding energies, and they would normally break down at temperatures far below those found in high-energy collisions. Somehow, though, their signature remains. This mystery has stumped physicists for decades, but researchers in the ALICE collaboration at CERN have now solved it. Their experiments showed that light nuclei form via a process called resonance-decay formation – a result that could pave the way towards searches for physics beyond the Standard Model.

 

Twistelastics controls how mechanical waves move in metamaterials

07 Nov 2025 Isabelle Dumé

How it works: Researchers use twisted surfaces to manipulate mechanical waves, enabling new technologies for imaging, electronics, and sensors. (Courtesy: A Alù)

By simply placing two identical elastic metasurfaces atop each other and then rotating them relative to each other, the topology of the elastic waves dispersing through the resulting stacked structure can be changed – from elliptic to hyperbolic. This new control technique, developed by physicists at the CUNY Advanced Science Research Center in the US, operates over a broad frequency range and has been dubbed “twistelastics”. It could allow for advanced reconfigurable phononic devices with potential applications in microelectronics, ultrasound sensing, and microfluidics.

 

Threads of fire: uncovering volcanic secrets with Pele’s hair and tears

17 Feb 2025 James Dacey

Volcanoes are awe-inspiring beasts. They spew molten rivers, towering ash plumes, and – in rarer cases – delicate glassy formations known as Pele’s hair and Pele’s tears. These volcanic materials, named after the Hawaiian goddess of volcanoes and fire, are the focus of the latest Physics World Stories podcast, featuring volcanologists Kenna Rubin (University of Rhode Island) and Tamsin Mather (University of Oxford).

Pele’s hair is striking: fine, golden filaments of volcanic glass that shimmer like spider silk in the sunlight.

 

Quantum fluids mix like oil and water

30 Oct 2025 Ali Lezeik 

Progression of the Rayleigh–Taylor instability: Initially, an applied force (grey arrows) destabilizes the fluid interface between spin-up (blue) and spin-down (yellow) sodium atoms. The interface then develops nominally sinusoidal modulations, where counterflowing currents in the two fluids (coloured arrows) induce vorticity at the interface (black symbols). The modulations subsequently acquire characteristic mushroom or spike shapes before dissolving into a turbulent mixture. (Courtesy: Taken from Science Advances 11 35, 10.1126/sciadv.adw9752, licensed under CC BY-NC)

Researchers in the US have, for the first time, replicated a well-known fluid-dynamics process called the Rayleigh–Taylor instability on a quantum scale. The work opens the hydrodynamics of quantum gases to further exploration and could even create a new platform for understanding gravitational dynamics in the early universe.

If you’ve ever tried mixing oil with water, you’ll understand how the Rayleigh–Taylor instability (RTI) can develop. Due to their different molecular structures and the nature of the forces between their molecules, the two fluids do not mix well. After some time, they separate, forming a clear interface between oil and water.

 

Shapiro steps spotted in ultracold bosonic and fermionic gases

12 Jan 2026

Stepping up Artist’s impression of how an analogue to a Josephson junction is created and modulated using lasers and an ultracold gas. (Courtesy: Technology Innovation Institute (UAE)

Shapiro steps – a series of abrupt jumps in the voltage–current characteristic of a Josephson junction that is exposed to microwave radiation – have been observed for the first time in ultracold gases by groups in Germany and Italy. Their work on atomic Josephson junctions provides new insights into the phenomenon and could lead to a standard for chemical potential.

In 1962, Brian Josephson of the University of Cambridge calculated that, if two superconductors were separated by a thin insulating barrier, the phase difference between their wavefunctions should induce quantum tunneling, leading to a current at zero potential difference.

 

Peer review in the age of artificial intelligence

18 Sep 2025 Hamish Johnston

It is Peer Review Week, and the theme for 2025 is “Rethinking Peer Review in the AI Era”. This is not surprising given the rapid rise in the use and capabilities of artificial intelligence. However, views on AI are deeply polarized for reasons that span its legality, efficacy, and even its morality.

A recent survey by IOP Publishing – the scientific publisher that brings you Physics World – reveals that physicists who peer-review are divided over whether AI should be used in the process.

 

Quantum information theory sheds light on quantum gravity

08 Jan 2026 Hamish Johnston

This episode of the Physics World Weekly podcast features Alex May, whose research explores the intersection of quantum gravity and quantum information theory. Based at Canada’s Perimeter Institute for Theoretical Physics, May explains how ideas being developed in the burgeoning field of quantum information theory could help solve one of the most enduring mysteries in physics – how to reconcile quantum mechanics with Einstein’s general theory of relativity, creating a viable theory of quantum gravity.