DESI’s data is consistent with the standard model of the Universe. However, when DESI’s new data is combined with other cosmic observations, scientists have discovered increasing evidence that the influence of dark energy is withering over time.
Those other observations include the light leftover from the dawn of the Universe (the cosmic microwave background), exploding stars (supernova), and how light from distant galaxies is warped by gravity (weak lensing).
Refine our understanding of the Universe
Professor Ofer Lahav from University College London (UCL) Physics and Astronomy, a DESI collaborator and member of its Executive Committee, said:
These new DESI observations, combined with other probes, suggest the intriguing possibility that the density of dark energy may be evolving with cosmic time. If confirmed, this would represent a paradigm shift in our understanding of the universe. If dark energy is constant, the universe would continue to expand at an accelerating rate forever. If it evolves with time, the fate of the universe is more uncertain.
UK scientists from Durham University, The University of Edinburgh, University College London (UCL), the University of Portsmouth, and other leading institutions have played a pivotal role in DESI’s instrumentation, data analysis, and cosmological modelling.
Their work has helped refine our understanding of the Universe’s fundamental forces and contributed to this latest research finding.
Key UK contributions
DESI is an international project with more than 900 researchers from over 70 institutions around the world, including the UK, and is managed by the US Department of Energy Lawrence Berkeley Lab.
The Science and Technology Facilities Council supports the UK component of the study.
Key contributions from the UK team include:
- Durham University developed DESI’s fibre-optic system, which channels light from galaxies onto the spectrograph, enabling high-precision measurements
- Durham University’s Dr Willem Elbers, co-chair of DESI’s cosmological parameter estimation group, led work on inferring cosmological parameters from the dataset
- Dr Pauline Zarrouk, formerly at Durham University, co-led an analysis confirming Einstein’s theory of gravity at cosmic scales using DESI’s data
- UCL designed and built DESI’s optical corrector, six lenses, the largest of which is 1.1m across, that focus light on to the fibre-optic system, ensuring accurate light capture for spectroscopic analysis
- Professor Seshadri Nadathur from the University of Portsmouth co-chaired DESI’s galaxy and Quasar clustering working group, leading the effort to extract dark energy measurements from DESI’s map
Paradigm shifts in our understanding
The fate of the Universe depends on the balance between dark matter and dark energy. The simplest model suggests that dark energy dominates today and is constant over time and so will continue to do so indefinitely.
Professor Ofer Lahav from UCL Physics and Astronomy, a DESI collaborator and a member of its Executive Committee, said:
Tracing the evolution of the dark energy concept over the past century is fascinating. It started with Einstein adding a number to his theory of general relativity to account for a static universe. He dismissed this number, known as a cosmological constant, when it became clear the universe was expanding. Then the idea was reclaimed to represent a constant dark energy driving the universe’s accelerated expansion.
Potential cracks in the model
Willem Elbers, a postdoctoral researcher at Durham University and co-chair of DESI’s cosmological parameter estimation working group, said:
For a couple of decades, we’ve had this standard model of cosmology that is really impressive. As our data is getting more and more precise, we’re finding potential cracks in the model and realising we may need something new to explain all the results together.
These findings strengthen hints that dark energy may not be constant over time, challenging the current standard model of cosmology.
Evidence is stronger than it ever was
Professor Seshadri Nadathur of University of Portsmouth said:
It’s not just that the data continue to show a preference for evolving dark energy, but that the evidence is stronger now that it was. We’ve also performed many additional tests compared to the first year, and they’re making us confident that the results aren’t driven by some unknown effect in the data that we haven’t accounted for.
DR1 available
Alongside unveiling its latest dark energy results, the DESI collaboration also announced that its Data Release One (DR1) is now available for anyone to explore.
DR1 contains a staggering 270 terabytes of information, surpassing all previous 3D spectroscopic surveys combined.
The full set of data release files are available to access through the National Energy Research Scientific Computing Centre, a facility at the Berkeley Lab, where DESI processes and stores data.
The DR1 main catalogues and spectra are available as searchable databases through the Astro Data Lab and SPARCL (Spectra Analysis and Retrievable Catalog Lab) at the Community Science and Data Centre, a programme of US National Science Foundation NOIRLab.
The collaboration shared their findings on 19 March 2025, in multiple papers that will be posted on the online repository arXiv and in a presentation at the American Physical Society’s Global Physics Summit in Anaheim, California.
Further information
UK involvement in DESI
DESI is an international project with more than 900 researchers from over 70 institutions around the world and is managed by the US Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab).
UK involvement in DESI includes Durham University, UCL and the University of Portsmouth as full member institutions, together with individual researchers at:
- the University of Cambridge
- The University of Edinburgh
- the University of St Andrews
- the University of Sussex
- the University of Warwick
About the University of Portsmouth
The University of Portsmouth is a progressive and dynamic university with an outstanding reputation for innovative teaching, outstanding learning outcomes and globally significant research and innovation.
Its 28,000-student population includes over 5,000 international and EU students from more than 150 countries. The city centre campus is at the heart of a lively city by the sea, on England’s south coast.
The university was awarded the highest overall rating of Gold in the most recent Teaching Excellence Framework, one of only 27 Gold rated universities in England and one of five Gold rated universities in the South East. It is proud to be one of the UK’s top 50 universities (with a five-star rating) in the QS World University Rankings and one of the top 10 Young Universities in the UK based on Times Higher Education Young University rankings.
Its research and innovation impacts lives today and in the future. Researchers work closely with business, industry and the public sector to solve local, national and global challenges across science, technology, humanities, business and creative industries.
Its world-class research is validated by its impressive Research Excellence Framework (REF) outcomes where Portsmouth was ranked third of all modern UK universities for research power in the Times Higher Education REF rankings.
For more information, visit the University of Portsmouth website.
About UCL, London’s global university
UCL is a diverse global community of world-class academics, students, industry links, external partners, and alumni. Their powerful collective of individuals and institutions work together to explore new possibilities.
Since 1826, the university has championed independent thought by attracting and nurturing the world’s best minds. Their community of more than 50,000 students from 150 countries and over 16,000 staff pursues academic excellence, breaks boundaries and makes a positive impact on real world problems.
The Times and Sunday Times University of the Year 2024, it is consistently ranked among the top 10 universities in the world and are one of only a handful of institutions rated as having the strongest academic reputation and the broadest research impact.
The university has a progressive and integrated approach to teaching and research. It champions innovation, creativity and cross-disciplinary working. It teaches students how to think, not what to think, and see them as partners, collaborators and contributors.
For almost 200 years, it is proud to have opened higher education to students from a wide range of backgrounds and to change the way it creates and shares knowledge.
It was the first in England to welcome women to university education and that courageous attitude and disruptive spirit is still alive today.
For more information, visit the UCL website.
About Durham University
Durham University is a globally outstanding centre of teaching and research based in historic Durham, a city in the UK.
It is a college university committed to inspiring its people to do outstanding things at Durham and in the world.
The university conducts research that improves lives globally and it is ranked as a world top 100 university with an international reputation in research and education (QS World University Rankings 2025).
It is a member of the Russell Group of leading research-intensive UK universities, and it is consistently ranked as a top 10 university in national league tables (Times and Sunday Times Good University Guide, Guardian University Guide and The Complete University Guide).
For more information, visit the Durham University website.
About Lawrence Berkeley National Laboratory
Lawrence Berkeley National Laboratory (Berkeley Lab) is committed to ground breaking research focused on discovery science and solutions for abundant and reliable energy supplies.
The lab’s expertise spans materials, chemistry, physics, biology, earth and environmental science, mathematics, and computing.
Researchers from around the world rely on the lab’s world-class scientific facilities for their own pioneering research. Founded in 1931 on the belief that the biggest problems are best addressed by teams, Berkeley Lab and its scientists have been recognised with 16 Nobel Prizes. Berkeley Lab is a multi programme national laboratory managed by the University of California for the US Department of Energy’s (DOE) Office of Science.
DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the US, and is working to address some of the most pressing challenges of our time.
For more information, visit the DOE website.