New cosmic research results confirm Einstein's Theory of Gravity
© 2024 EPFL
The Dark Energy Spectroscopic Instrument is a large-scale astronomical survey designed to map the universe in three dimensions, aiming to deepen our understanding of the cosmos, particularly focusing on dark energy and gravity at cosmological scales. In its first year of data collection, DESI hs mapped nearly 6 million galaxies across 11 billion years of cosmic history. These observations confirm Einstein's theory of general relativity on cosmological scales with greater precision than in the past twenty years.
A global consortium of researchers, including at EPFL’s Laboratory of Astrophysics, has found that Einstein’s general theory of relativity correctly predicts how gravity behaves over 11 billion years of cosmic history.
Gravity has shaped our cosmos. Its attractive influence turned tiny differences in the amount of matter present in the early universe into the sprawling strands of galaxies we see today.
Now, a new study using data from the Dark Energy Spectroscopic Instrument or DESI, an international collaboration of more than 900 researchers from over 70 institutions around the world including EPFL, has traced how this cosmic structure grew over the past 11 billion years, providing the most precise test to date of gravity at very large scales.
Looking at galaxies and how they cluster across time reveals the growth of cosmic structure, which lets DESI test theories of modified gravity – an alternative explanation for our universe’s accelerating expansion.
A complex analysis of DESI’s first year of data is one of the most stringent tests yet of general relativity and how gravity behaves at cosmic scales. DESI researchers found that gravity behaves as predicted by Einstein’s theory of general relativity.
“General Relativity explains the gravitation law by the distortion of Space-Time, and is a remarkable match to the measurements on the scale of the solar system. Yet on the scale of the universe alternative models have been explored to possibly address the problem of Dark Matter and Dark Energy. The new measurements of DESI on the galaxy large-scale structure limit the possible theories of modified gravity and is in line with Einstein’s theory” explained Professor Jean-Paul Kneib, Head of EPFL’s Laboratory of Astrophysics (LASTRO), in the School of Basic Sciences.
LASTRO has contributed to the development of the DESI survey’s targeting strategy (deciding which of the galaxies will be observed), the scientific analysis of data coming in from the survey, and the development of the instrument’s robotic fiber-positioner system, including tilt-verification tests on some DESI positioners to validate their performance.
The latter was conducted as part of the interdisciplinary "Astrobots" group, which includes LASTRO, as well as Mohamed Bouri and Denis Gillet’s teams from the School of Engineering.
A group of young scientists from the LASTRO has been heavily involved in interpreting the enormous amount of data coming in from DESI by characterizing their physical meaning through the construction of advanced numerical modeling and the simulation of our Universe. Among them, Dr. Daniel Forero-Sanchez, a recent graduate student at LASTRO, co-led the work on measurement errors. Handling the errors on these measurements is one of the key points in drawing confident conclusions from the analysis.
DESI is a state-of-the-art instrument that can capture light from 5,000 galaxies simultaneously and made Time Magazine's list of best inventions of 2024. The collaboration is currently analyzing the first three years of collected data and expects to present updated measurements on dark energy and the expansion history of our universe in early 2025. DESI’s expanded results released today are consistent with the experiment’s earlier preference for an evolving dark energy, adding to the anticipation of the upcoming analysis.
The DESI collaboration is honored to be permitted to conduct scientific research on Iolkam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O’odham Nation.
DESI is managed by the Department of Energy's Lawrence Berkeley National Laboratory and supported by the US DOE Office of Science and by the National Energy Research Scientific Computing Center, a DOE Office of Science user facility. Additional support for DESI is provided by the U.S. National Science Foundation; the Science and Technology Facilities Council of the United Kingdom; the Gordon and Betty Moore Foundation; the Heising-Simons Foundation; the French Alternative Energies and Atomic Energy Commission (CEA); the National Council of Humanities, Sciences, and Technologies of Mexico; the Ministry of Science and Innovation of Spain; and by the DESI member institutions. EPFL and the Swiss National Science Foundation have contributed almost 1 million CHF towards the construction of DESI.
