School of Physics and Astronomy

Scientists at the Dark Energy Survey (DES) collaboration, have released their latest and most detailed picture yet on how the universe has expanded over the last six billion years.

A century of discovery

Around 100 years ago, scientists discovered that distant galaxies appeared to be moving away from Earth. They found that the further away a galaxy is, the faster it recedes, providing the first key evidence that the universe is expanding.

Researchers initially expected that this expansion would slow down over time due to gravity.  However, in 1998, observations of distant supernovae revealed that the universe’s expansion is accelerating rather than slowing down.

To explain this surprising result, scientists proposed the idea of dark energy, which is now thought to drive the universe’s accelerated expansion.

Astrophysicists believe dark energy makes up about 70% of the mass-energy content of the universe, yet we still know very little about it.

Combining four cosmic probes

These recent findings combine results from 18 separate studies and, for the first time, bring together four major techniques for studying dark energy within a single experiment, a milestone envisioned when DES was conceived 25 years ago. These techniques are:

• weak gravitational lensing (distortions in galaxy shapes)
• galaxy clustering
• supernovae
• galaxy clusters

The combination of these techniques enabled scientists to cross-check their measurements and gain a more robust understanding of how the universe behaves.

International collaboration

The Dark Energy Survey is an international collaboration of more than 400 astrophysicists, astronomers and cosmologists from over 35 institutions. The international research team is led by the US Department of Energy’s Fermi National Accelerator Laboratory, with UK support from the Science and Technology Facilities Council (STFC) and six UK universities, including the University of Edinburgh.

Through STFC, the UK is also supporting research programmes that will advance DES science in the next generation of astronomical surveys, including the Vera C. Rubin Observatory, currently under construction in Chile.

Professor Joe Zuntz, Personal Chair of Cosmology, Institute for Astronomy, University of Edinburgh, said:

As well as needing a fantastic telescope, research like this needs supercomputers to tell us what the data actually means. That’s one reason why the UK’s next supercomputer, being hosted in Edinburgh, is so valuable and why I’m proud to develop the programming to help scientists understand what DES’s measurements can tell us about the Universe.

Far reaching science

To study dark energy, the DES collaboration carried out a deep, wide-area survey of the sky between 2013 and 2019, using a specially constructed 570-megapixel Dark Energy Camera mounted on a telescope at the US National Science Foundation’s Cerro Tololo Inter-American Observatory in Chile.

Over six years, scientists collected images and data from hundreds of millions of distant galaxies, billions of light-years from Earth, mapping about one-eighth of the sky.

For the latest results, scientists refined how they use subtle distortions in galaxy shapes, known as weak gravitational lensing, to reconstruct the distribution of matter in the universe over six billion years. They did this by measuring both how galaxies cluster together and how similarly their shapes are distorted by gravity.

By reconstructing the universe’s matter distribution across 6 billion years, these measurements reveal how dark energy and dark matter have influenced the universe’s evolution.

A mystery remains

The team compared their observations with two main theories, one in which dark energy remains constant over time (the standard model of cosmology), and another in which dark energy changes as the universe evolves.

DES found that although the data mostly align with the standard model, broadly agreeing with the most widely accepted theory of the universe, there remains a long-standing discrepancy in how matter clusters in the universe, and this has become more pronounced with the inclusion of the full dataset.

Paving the way

Looking ahead, DES will combine these latest findings with results from other dark energy experiments to explore and test alternative ideas about gravity and dark energy.

The work also helps prepare the ground for future breakthroughs at the upcoming Vera C. Rubin Observatory in Chile to do similar work with its Legacy Survey of Space and Time (LSST).

Congratulations to Professor Steve Tobias who has been appointed a Fellow of the Academy for the Mathematical Sciences.

Fluid dynamics

Professor Tobias is an applied mathematician who conducts research in mathematical aspects of fluid dynamics and magnetohydrodynamics, with applications in both geophysics and astrophysics. He is particularly interested in turbulent flows and turbulent dynamo theory, where the nonlinear interactions occur over a vast range of temporal and spatial scales, necessitating the development of new mathematical and computational techniques. He currently holds the Tait Chair of Mathematical Physics at the University of Edinburgh.

Academy Fellows

The Academy for the Mathematical Sciences has a vision to bring together the UK’s strongest mathematicians across academia, education, business, industry, and government to help solve some of the UK’s biggest challenges and to provide an authoritative, persuasive and influential voice for the whole of the mathematical sciences for the benefit of all.

In this inaugural process, 100 Fellows have been appointed; included among their number are winners of the Fields Medal (the mathematics equivalent of a Nobel Prize), leading business people, distinguished teachers and academics, science communicators, and pioneers of computing and machine learning. This appointment includes five members of the University of Edinburgh.

Much like Fellows of the other National Academies (Royal Society, Royal Academy of Engineering, British Academy and the Academy of Medical Sciences), the Fellows of the Academy for the Mathematical Sciences have been recognised for being leaders in their fields, through fundamental discoveries, exceptional work in education, or driving the application of mathematics across society as part of our critical national infrastructure.

Fellows will act as leading ambassadors for the Academy, and as key points of contact and connectivity between the mathematical sciences community, the Academy, and the wider world of industry, government, learning and society.

Professor Dame Alison Etheridge DBE FRS, the President of the Academy for Mathematical Sciences, said:

I’m delighted to welcome our inaugural Fellows — individuals of exceptional distinction who collectively advance the mathematical sciences through discovery, leadership, education and real-world application.

Congratulations to Dr Sally Shaw who has been awarded the 2025 Chancellor’s Award: Rising Star.

Chancellor’s Awards

The Chancellor’s Awards are one of the most important ways in which the University recognises current members of the University community who have made outstanding contributions to teaching or research, achieved national and international recognition for their work, or made an outstanding contribution to the University's work in general.

The awards were presented by the Chancellor, Her Royal Highness The Princess Royal, during a gala dinner held this week at the Palace of Holyroodhouse. The Lord Provost, Councillor Robert Aldridge, joined in congratulating the winners.

Rising Star Award

The Rising Star Award honours an early career colleague who has made a significant contribution in their role.

Dr Sally Shaw is a Lecturer in Experimental Particle Physics in the School of Physics and Astronomy. Sally received the Rising Star Chancellor’s Award in recognition of her outstanding reputation in the field of dark matter detection, and her outstanding leadership in both research and in public outreach programmes.

Dark Matter

Sally’s research focusses on the direct detection of dark matter - an elusive substance that comprises 80% of the matter in the universe but remains one of the biggest mysteries in modern science. She is a recognised leader in the field, having delivered world-leading results as the LZ experiment’s Physics Coordinator. Furthermore, she is leading delivery of the largest component of LZ’s scaled-up successor, XLZD, and is one of the UK academics driving the effort to host XLZD in the UK at the Boulby Underground Laboratory. 

Championing inclusion and opportunities in physics

As one of a small number of female academics in her discipline and a first-generation university graduate, Sally has been a driving force in public engagement and equity, diversity and inclusion within the particle physics community and at Edinburgh, with a particular focus on encouraging under-represented groups into physics and engaging schools in remote and deprived areas.

Dr Sally Shaw said:

I feel extremely honoured to have been recognised through this award after a very busy start to my career at the University of Edinburgh. My work would not have been possible without being surrounded by the world-class physicists and amazing professional services staff who have been nothing but welcoming and supportive since I got here.

Scientists have uncovered a previously hidden way that hydrogen molecules can move when subjected to extreme conditions.

Researchers at the Centre for Science at Extreme Conditions (CSEC) have observed a new type of quantum excitation in solid hydrogen, deuterium and the mixture of the two. Their results show that solid hydrogen molecules can only point in certain directions, and that anything in between is forbidden by the rules of quantum mechanics.

Hydrogen and quantum mechanics

The hydrogen molecule (H₂) is one of the simplest systems in quantum mechanics, and along with its well-defined spectroscopic properties, it makes a good textbook example for illustrating key concepts. The fundamental principle of quantum mechanics is that the energy of molecules is only allowed to have discrete values: quantum level. Until now, spectroscopic work detected two types of motion - vibrations and rotations. These are determined using a laser energy to speed up the rotation or vibration and measuring the ratio of the energy of quanta between hydrogen and deuterium. Fundamental quantum mechanics predicts that rotations vary by a factor of 2, vibrations by √2. This is because rotations have only kinetic energy, whereas vibrations have both kinetic and potential energy. 

A predicted but previously unseen excitation

However, a third type of excitation, with changes to potential energy only, was theorised by Professor Ackland. This is based on reorientation of the molecule while the total angular momentum is unchanged, so-called ΔJ = 0 or ‘zero-roton’ transitions where J labels the rotational energy. In a gas or liquid, such transitions are undetectable because there is no energy change to measure. However, when hydrogen enters a high-pressure solid state, the crystal field environment alters its symmetry: again quantum mechanics insists that the molecule orientates in one of a few fixed directions, nothing in between, but now these ΔJ = 0 reorientation transitions involve an energy change which can be detected by Raman Spectroscopy. However, because the energy change is small, the signal is exceptionally difficult to detect and had never been directly captured experimentally. This is despite the fact that the energy change is the same for both deuterium and hydrogen. 

Detecting an exceptionally faint signal

Using a sensitive Raman spectroscopy system, Professor Gregoryanz’s team conducted systematic spectroscopic measurements across a range of pressure and temperature conditions. They studied dense hydrogen, deuterium, and mixtures of the two, unambiguously observing this ‘hidden’ excitation signal for the first time. They found that in the gas and liquid state this excitation has, as theory suggests, zero Raman shift, but in the solid state, the crystal field drives it away from the zero value e.g. ~150 cm−1 at above 100 GPa and 20-45 K for both isotopes. Furthermore, the frequency of the ΔJ = 0 transition exhibits complete isotope independence, representing a novel excitation mode distinct from traditional harmonic oscillators and quantum rotors. The research further revealed the unique behaviour of this excitation during conversion between the different forms of hydrogen (known as ortho-para conversion). These observations provide crucial experimental clues for understanding the evolution of hydrogen's quantum states under extreme conditions.

From prediction to proof

Professor Gregoryanz said: 

We have known that the zero-roton excitation was there for more than 10 years, having observed it in previous work. But working on other effects meant that we never had the opportunity to pursue it. It is now very exciting to finally sort out and understand it – what we once saw as a nuisance turned out to be something fundamental.

Professor Ackland said: 

The prediction of the ΔJ = 0 transition was a central feature of the project, and in retrospect we even observed it in previous experiments: but to prove that the signal is indeed the zero-roton, and not some other effect, required incredibly precise work under extremely challenging experiments. As a theorist, it is thrilling to see the effect finally proven.

This discovery completes the final experimental observation of all allowed types of quantum transition in dense hydrogen, revealing the complete manifestation of Raman selection rules modified by a crystal field. It also provides a unique example showcasing the novel physics emerging in fundamental quantum systems under extreme conditions. 

These results were published in Physical Review Letters, and the work was supported by the EPSRC, ERC, and a range of Chinese Funding agencies.

School receives Silver Lab Award for sustainable research practices.

The School of Physics and Astronomy, including the Centre for Science at Extreme Conditions (CSEC), has taken a significant step towards a greener research culture, building on its Changemaker Award in the School’s Biolabs, achieved in 2023. The School has now strengthened its commitment to environmental stewardship by achieving the prestigious Silver Sustainable Lab Award under the University’s Sustainable Lab Awards programme.

This accreditation is designed for wet-lab environments—settings where energy, water, and chemical consumption can be particularly intensive—and recognises proactive efforts to embed sustainability into day-to-day research practices.

The Silver Lab Award acknowledges teams that go beyond basic compliance, implementing resource-efficient procedures and environmentally responsible ways of working. Silver-level criteria cover a wide range of areas, including energy efficiency, waste reduction and recycling, cold-storage optimisation, chemical and gas handling, water minimisation, and knowledge sharing, all building on the foundational Bronze standards.

Importantly, the School’s achievement aligns with emerging expectations across the research landscape. Major UK and international funders are increasingly requiring applicants to demonstrate concrete commitments to sustainability as part of grant eligibility and assessment. Organisations such as the Wellcome Trust and Cancer Research UK are now integrating environmental sustainability criteria into their funding processes, asking applicants to show how their research will reduce resource use and associated emissions.

For the School of Physics and Astronomy, attaining the Silver Award not only supports the University’s Strategy 2030 sustainability ambitions, but also positions the School to meet these evolving expectations from external funders.

This project was led by Neil Corsie (Health & Safety Manager and Deputy Technical Services Manager), with the essential work carried out by the School’s dedicated laboratory technicians and staff, and with valuable support from the Head of School.

Scientists on the MicroBooNE experiment are closing the door on one explanation for a neutrino mystery that has plagued them for decades.

Latest results

An international collaboration of scientists working on the MicroBooNE experiment announced that they have found no evidence for a fourth type of neutrino.

Earlier physics experiments saw neutrinos behaving in a way inconsistent with the Standard Model of particle physics. Theorists have suggested that a sterile neutrino could explain those anomalies.

However, with this new result, MicroBooNE has been able to rule out a single sterile neutrino explanation with 95% certainty.

The Standard Model & Neutrinos

The Standard Model is the best theory scientists have for explaining how the universe works. However, it is incomplete as it doesn’t account for dark matter, dark energy or gravity.

Physicists are therefore on the hunt for new physics that may shed light on some of the biggest mysteries in the universe, and part of this search leads them to study neutrinos.

According to the Standard Model there are three types, or flavours, of neutrino: muon, electron and tau. A number of mysteries surround these subatomic particles, and scientists observed unexpected behaviour that led them to consider the possibility of a sterile neutrino.

Edinburgh involvement

Researchers at the University of Edinburgh’s School of Physics and Astronomy have led the development of using the NuMI (Neutrinos at the Main Injector) beam for neutrino measurements, specifically the first measurements of electron-neutrino interactions on argon.

Edinburgh scientists have also led the major effort to process the data and simulations used to obtain these most recent results. Currently, the group is working on novel methods of identifying neutrinos from anti-neutrinos using their topologies, and is also working on the next generation measurements with the recently turned on Short-Baseline Near Detector (SBND) experiment.

What is MicroBooNE?

MicroBooNE is the first large liquid-argon time projection chamber to acquire a high-statistics sample of neutrino interactions. MicroBooNE’s cutting-edge technology can record incredibly precise 3D images of neutrino events, providing detailed information about how these elusive particles interact.

MicroBooNE is one of three experiments hosted by the Fermi National Accelerator Laboratory short-baseline (or short-distance) neutrino program.

The MicroBooNE is managed by the U.S. Department of Energy’sFermi National Accelerator Laboratory and the collaboration consists of 193 scientists from 40 institutions, including national labs and universities from six countries.

This latest research was published in Nature.

Science exhibition attendees learned about the mysterious substance that makes up around 80% of all matter in the universe.

Visitors at the New Scientist Live event in London had the opportunity to step into a life-sized detector to hunt for dark matter signals.

Attendees also had the chance to engage with hands-on activities explaining dark matter, and a Cosmic Cube detecting live cosmic rays.

The ‘Underground Dark Matter Searches UK’ stand was designed by researchers from the University of Edinburgh. The walk-in detector used data from the LUX-ZEPLIN dark matter experiment, which is located 1 mile underground in South Dakota, USA, to light up 240 LEDs with the same patterns seen in the real detector.

What is dark matter?

Scientists are not sure yet, but they know it makes up 80% of the matter in our universe, and that it shapes galaxies and holds cosmic structures together. They think that dark matter may be a new fundamental particle - called a WIMP (Weakly Interacting Massive Particle). The hunt for WIMPs leads them deep underground where experiments, such as the LUX-ZEPLIN (LZ) detector, are shielded from cosmic rays. Scientists from UK institutions are key contributors to the LZ experiment. The next generation dark matter detector, XLZD, will take us even closer to answering one of the greatest mysteries of modern physics. Several sites are being considered to host this detector, with the shortlist including the UK’s Boulby Underground Laboratory.

New Scientist Live

New Scientist Live brings together experts in science, technology and innovation for three days of discovery each autumn.

With over 26,000 people attending, 70 inspiring speakers, five dynamic stages and more than 90 hands-on exhibits, visitors explored everything from the mysteries of the cosmos to the future of health, climate and AI.

Thanks to colleagues from the LUX-ZEPLIN and XLZD collaborations for their contribution to the Underground Dark Matter Searches UK stand.

Congratulations to students who received medals, certificates, prizes and scholarships at the School’s Undergraduate and MSc Student Awards Ceremony.

Head of School, Professor Philip Best announced the awards in recognition of excellent performance and achievements from Undergraduate and MSc students during the past academic year.

Certificates & Medals

164 pre-honours students (years 1 & 2) received Certificates of Merit for outstanding marks in their pre-honours courses. Class Medals are awarded to individuals who have received the highest overall mark for their degree programme, with 23 undergraduate and 4 MSc students in receipt of Class Medals.

Prizes and Scholarships

The School has a number of Prizes and Scholarships to award, including a prize for the year 5 student with the highest classification on the Astrophysics MPhys programme, a prize for the year 4 student with the best Senior Honours poster, and a prize for the student who has produced the best Summer Scholarship Poster. A total of 25 Prizes and Scholarships were awarded to the undergraduate students who achieved outstanding results in their subject area or year. 

Many congratulations to all recipients.

In two related studies, scientists uncover surprising insights into the chemistry of giant planets.

What is metallic hydrogen?

Metallic hydrogen is believed to be the most abundant condensed material in the universe, existing deep inside giant planets such as Jupiter and Saturn.

Because metallic hydrogen can only form under immense pressures, it has been almost impossible to study in the laboratory. As a result, much of what scientists know about this material comes from theoretical models.

A new theoretical study has revealed that chemistry in the extreme environments of metallic hydrogen could be far more complex than previously thought.

Scientists used quantum mechanics to investigate how carbon, nitrogen and oxygen behave in metallic hydrogen.

Their simulations revealed that these elements can react with each other and with hydrogen to form stable, covalently bonded molecules — including CH₆, C₂H₈, C₃H₁₀, OH₃, NH₄ and CH₄OH. These compounds are known as hypermolecules, due to their unusually high hydrogen content.

Remarkably, the findings suggest that organic molecules can survive in the extreme pressures and temperatures of planets such as Jupiter and Saturn — conditions that are very different from those found on Earth.

Juno space probe

If organic molecules can survive in the extreme pressures of these planets, one might assume we could find them there.

Planets are expected to have a structure where the heaviest elements fall to the centre, forming a heavy core: for Earth this is mainly molten iron. Giant planets are mainly formed of hydrogen, and as a result of the extreme pressures deep in their interior, the hydrogen becomes first liquid, then metallic.  

Cast your mind back to 2016, when NASA’s Juno space probe arrived on Jupiter to undertake a mission to explore the planet. It was predicted that Jupiter’s core might consist of giant diamonds, rocks, ice or heavy metals. What they found was more surprising - there is no core.

In studies led by the Edinburgh team, results show that almost all elements will dissolve in metallic hydrogen, and so any heavy elements on a planet such as Jupiter are largely dissolved within the hydrogen layer.

Crucially, the study also indicates that carbon, oxygen and nitrogen may dissolve readily in metallic hydrogen. This raises new questions about the internal structure of giant planets and whether they can contain distinct rocky cores, as often assumed.

By providing the first detailed picture of possible chemical interactions in metallic hydrogen, these research studies open a new window on planetary science and high-pressure chemistry.

The late Professor Peter Higgs has gifted his Nobel Prize to the University of Edinburgh, where he first proposed an idea that would transform our understanding of the universe.

The pioneering physicist has left the internationally prestigious medal to the institution in his will, following his death aged 94 in April 2024.

It will be preserved by the University’s Centre for Research Collections and displayed at events and exhibitions, including the upcoming Higgs Lecture in 2026.

Professor Higgs is known and lauded worldwide for predicting the existence of a fundamental physical particle that came to bear his name – the Higgs boson. 

He was a researcher at the University of Edinburgh in 1964 when he predicted the particle, which enables other particles to acquire mass. 

This idea was validated by experiments almost 50 years later, at the European Organization for Nuclear Research (CERN) in Switzerland in 2012. 

The discovery was followed by the award of a Nobel Prize in Physics for Professor Higgs in 2013, which he shared with François Englert of Belgium. 

Professor Sir Peter Mathieson, Principal and Vice-Chancellor of the University of Edinburgh, said:

This generous gift will ensure that Peter Higgs’ extraordinary contributions to science will continue to inspire generations of students and researchers. We are profoundly honoured to have been entrusted with his Nobel Prize medal, an object of immense historical significance and a lasting emblem of his legacy.

Born in 1929 in Newcastle upon Tyne, Peter Higgs joined the staff of the University of Edinburgh in 1960, when he took up a lectureship at the Tait Institute of Mathematical Physics and became Personal Chair of Theoretical Physics in 1980. He retired in 1996, becoming Professor Emeritus. 

The Higgs Centre for Theoretical Physics was established by the University of Edinburgh in 2012 to recognise Professor Higgs’ achievements and create opportunities for students and researchers from around the world to formulate new theoretical concepts.

Professor Neil Turok, Higgs Chair of Theoretical Physics at the University of Edinburgh, said:

The prediction of the Higgs boson was a theoretical breakthrough, fundamental to our understanding of the laws of physics. It is fitting that Peter Higgs’ Nobel Prize medal is now preserved at Edinburgh, forming a lasting part of the University’s scientific heritage. Through our Higgs Centre for Theoretical Physics, his seminal discovery continues to serve as a springboard for those seeking answers to some of the deepest mysteries of our universe.

A plaque commemorating Professor Higgs’ legacy can be found at Roxburgh Street in Edinburgh. The installation marks the site where he first devised the theory of the Higgs boson particle.