Ann Arbor Times

The Dark Energy Spectroscopic Instrument (DESI) has provided new insights into the universe's structure, examining how cosmic formations have developed over the past 11 billion years. This research offers a precise test of gravity on a grand scale.

DESI, an international collaboration involving more than 900 researchers from over 70 institutions, is managed by the Department of Energy’s Lawrence Berkeley National Laboratory. It confirms existing models of the universe and limits theories suggesting modified gravity to explain the universe's accelerated expansion.

“This is the first time that DESI has looked at the growth of cosmic structure,” said Dragan Huterer, a physics professor at the University of Michigan and co-lead in analyzing cosmological data for DESI. “DESI data have a tremendous ability to probe modified gravity and improve constraints on models of dark energy.”

Pauline Zarrouk, a cosmologist with France's National Center for Scientific Research, highlighted DESI's validation of Einstein’s general relativity at large scales: “Studying the rate at which galaxies formed lets us directly test our theories and, so far, we’re lining up with what general relativity predicts at cosmological scales.”

The study also sets new upper limits on neutrino masses. While previous experiments suggested a minimum sum mass for neutrinos, DESI results indicate it should be less than 0.071 eV/c2.

Using nearly six million galaxies and quasars, DESI has achieved precise measurements within its first year of data collection. The instrument uses robotic "eyes" to capture light from thousands of galaxies simultaneously.

Gregory Tarlé from U-M led the team responsible for these robotics. “We control the position to better than one tenth the diameter of a human hair,” he explained.

DESI's survey is in its fourth year and aims to analyze around 40 million galaxies by project completion. Future updates are expected in spring 2025 as analysis continues.

“Without those 5,000 eyes in the sky, we wouldn’t be doing any of this now,” Huterer stated.

Constructed with funding from various scientific bodies including DOE Office of Science and mounted on NSF’s Nicholas U. Mayall Telescope at Kitt Peak National Observatory, DESI continues to explore fundamental questions about dark energy and matter distribution in space.

Mark Maus from Berkeley Lab emphasized the importance of tackling these questions through observations: “The idea that we can take pictures of the universe and tackle these big, fundamental questions is mind-blowing.”

Huterer noted that while multiple mysteries remain unsolved, understanding dark energy remains crucial: “The most important thing is still dark energy...this is only the first salvo of analysis.”