Albert Einstein’s transformational prediction about how gravity behaves has been backed by an international team of researchers who studied how the force acts on cosmic scales.
Scientists, including astrophysicists from the Institute for Computational Cosmology of Durham University, used the Dark Energy Spectroscopic Instrument (DESI) to map how nearly six million galaxies cluster across 11 billion years of time.
Their complex analysis of DESI’s first year of data provides one of the most stringent tests yet of Einstein’s famous theory of General Relativity and how gravity behaves at cosmic scales.
Looking at galaxies and how they cluster throughout time reveals how the Universe’s structure has grown.
This allowed DESI’s scientists to test theories of modified gravity – an alternative explanation for our Universe’s accelerating expansion typically attributed to dark energy.
They found that the way galaxies cluster is consistent with our standard model of gravity and the predictions made by Einstein.
The result validates the leading model of the Universe and limits possible theories of modified gravity, which have been proposed as alternative ways to explain unexpected observations such as the accelerated expansion of the universe.
General Relativity is one of the most elegant and profound theories in Physics. That the Universe seems to conform to its precepts is truly remarkable, a testament to Einstein’s talent and to that of the astronomers who have devised methods to test it.
Durham University researchers Dr Willem Elbers and Professor Carlos Frenk, of our Institute for Computational Cosmology, co-led a detailed analysis of the DESI data, which provided new upper limits on the mass of neutrinos, the only fundamental particles whose masses have not yet been precisely measured in the laboratory.
Neutrinos influence the clustering pattern of galaxies ever so slightly, but this can be measured with the quality of the DESI data.
With these results, we are finally closing in on the mass of the neutrinos, particles whose mere detection was once thought impossible. Although the gravity from any one neutrino is negligible, their sheer abundance means that, collectively, neutrinos are a force of cosmological consequence, capable of moving entire clusters of galaxies. It is remarkable that DESI is able to measure these effects.
Durham University is a key member of the DESI collaboration and designed and built the fibre optic system which funnels light onto DESI’s spectrograph.
Durham scientists also carried out supercomputer simulations of the Universe, crucial for the interpretation of DESI’s data.
DESI’s latest results were published in a series of papers on the arXiv open-access archive.
Durham’s involvement in DESI is led by our Institute for Computational Cosmology working with our Centre for Advanced Instrumentation and Centre for Extragalactic Astronomy.
Our Department of Physics is ranked 69th in the QS World University Rankings by Subject 2024. Visit our Physics webpages for more information on our undergraduate and postgraduate programmes.
DESI is managed by the United States’ Department of Energy’s (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) with primary funding for construction and operations from the DOE’s Office of Science. Additional support for DESI is provided in the UK by Durham University, University College London (UCL) and the UKRI Science and Technology Facilities Council.
DESI sits atop the US National Science Foundation’s (NSF) Nicholas U Mayall 4-metre Telescope at Kitt Peak National Observatory, a programme of NSF’s NOIRLab, in Arizona, USA. The DESI collaboration is honoured to be permitted to conduct scientific research on I’oligam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O’odham Nation.
Main image: DESI observes the sky from the Mayall Telescope, shown here during the 2023 Geminid meteor shower. Credit: KPNO/NOIRLab/NSF/AURA/R. Sparks.
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