Evrim Yazgin
Cosmos science journalist
This week both the Dark Energy Survey (DES) and the Dark Energy Spectroscopic Instrument (DESI) collaboration have released massive datasets which are immediately challenging cosmologists’ best theories of the universe.
The new studies are available in preprint papers and are being presented at American Physical Society’s Global Physics Summit in California.
“What we are seeing is deeply intriguing,” says Alexie Leauthaud-Harnett from the University of California, Santa Cruz and co-spokesperson for DESI. “It is exciting to think that we may be on the cusp of a major discovery about dark energy and the fundamental nature of our universe.”
“This is a major moment for cosmology,” says Rossana Ruggeri, co-author on some of the new analysis and a cosmologist at Australia’s Queensland University of Technology.
“Dark energy is believed to permeate all of space, causing the accelerated expansion of the universe. It makes up about 70% of the universe, but its nature is one of the most significant puzzles in modern physics.
“The DESI first-year result papers were among the most cited papers in 2024 in the field of cosmology, and these new results suggest that dark energy may not be constant as previously thought – a potentially big shift in our understanding of the universe.”
The standard model of cosmology which explains the evolution of the universe since the Big Bang is based on the mathematical model called “Lambda cold dark matter”, ΛCDM or Lambda-CDM. Despite little hiccups over the decades, the model has been successful in describing large-scale structures in the universe.
Baryon Acoustic Oscillations (BAO) and distance measurements of Type Ia Supernovae are key quantities for studying the universe’s expansion history.
Santiago Avila from the Centre for Energy, Environmental and Technological Research (CIEMAT) in Spain, who was part of the DES analysis says by analysing 16 million galaxies, DES found that the measured BAO scale is actually 4% smaller than predicted by ΛCDM.
“This result is intriguing because it hints at physics beyond the standard model of cosmology,” says Juan Mena-Fernández of the Subatomic Physics and Cosmology Laboratory in Grenoble, France. “If further data support these findings, we may be on the brink of a scientific revolution.”
The final DES results are expected later this year.
Meanwhile, DESI has just made public the largest 3D map of the universe as part of its first data release.
