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DESI’s latest measurements suggest dark energy may be changing over time: Study

Its most recent Data Release (DR2), based on the first two years of observations, contains precise measurements from nearly 15 million cosmic objects, producing the most detailed 3-D map of the Universe ever created.

3 min readPuneUpdated: Nov 14, 2025 07:02 PM IST

Some of these galaxies lie over 15 billion light years away, enabling DESI to probe the expansion history deep into cosmic time.

Latest results from the Dark Energy Spectroscopic Instrument (DESI) suggest that dark energy (DE) may be decaying with time rather than remaining constant.

DESI is a powerful survey mounted on the Mayall 4-metre telescope at Kitt Peak National Observatory in Arizona and has released its latest measurements of the Universe’s expansion -that have generated major excitement across the global scientific community.

In their work, authors Swagat Saurav Mishra — who did his PhD from Inter-University Centre for Astronomy and Astrophysics, Pune and is now at School of Physics and Astronomy, University of Nottingham, UK; Prof Varun Sahni from IUCAA, William L Matthewson, Arman Shafieloo, and Yuri Shtanov present a simple explanation for why DESI’s latest measurements suggest that dark energy may be changing over time.

“DESI has been operational since 2021 and is carrying out a five-year programme to map the positions and distances of more than 40 million galaxies. Its latest results suggest that dark energy, the mysterious force driving cosmic acceleration, may not be constant after all. Instead, it could be dynamical, gradually changing with time. More specifically, DESI’s observations indicate that dark energy was increasing in density in the distant past, but around 5 billion years ago it began to decay and slowly dilute. If confirmed, this behaviour would challenge the long-standing “cosmological constant” model and open the door to entirely new physics. Although the Universe appears to be accelerating today, a decaying dark energy component would have profound implications for its future — very different from the standard scenario in which a constant dark energy density drives eternal acceleration and suppresses the formation of new cosmic structures,” Mishra said.

Its most recent Data Release (DR2), based on the first two years of observations, contains precise measurements from nearly 15 million cosmic objects, producing the most detailed 3-D map of the Universe ever created. Some of these galaxies lie over 15 billion light years away, enabling DESI to probe the expansion history deep into cosmic time. The second data release (DR2), the most precise measurement yet of cosmic expansion, points to models in which the density of dark energy gradually evolves as the Universe expands,” Prof Mishra added.

Study authors explained that these predictions will be scrutinised further by DESI’s upcoming data releases, as well as by new space missions such as Euclid and the Roman Space Telescope. If the model’s predictions continue to hold,it could provide the first observational hints that our Universe possesses more dimensions than the ones we directly perceive — a discovery with far-reaching implications for fundamental physics,” Prof Mishra also said.

Way forward

DESI has opened an exciting new window. For the first time, large-scale observations may be pointing beyond the long-standing cosmological constant. Study authors said that with another DESI data release (DR3) expected in 2026, the current evidence remains preliminary, but the implications are striking. “A time-varying dark energy component could fundamentally reshape our understanding of how the cosmos will evolve: whether expansion will continue indefinitely, slow down, or take a completely different turn. In response, a major global theoretical effort is now underway to develop physical models of dark energy that can naturally explain DESI’s hints and offer clear, testable predictions for upcoming surveys,” Prof Mishra observed

Anuradha Mascarenhas

Anuradha Mascarenhas is a Senior Editor at The Indian Express, based in Pune. With a career spanning three decades, she is one of the most respected voices in Indian journalism regarding healthcare, science and environment and research developments. She also takes a keen interest in covering women's issues . Professional Background Education: A gold medalist in Communication and Journalism from Savitribai Phule Pune University and a Master’s degree in Literature. Author: She authored the biography At The Wheel Of Research, which chronicles the life and work of Dr. Soumya Swaminathan, the former Chief Scientist at the WHO. Key Focus: She combines scientific accuracy with storytelling, translating complex medical research into compelling public and human-interest narratives. Awards and Recognition Anuradha has won several awards including the Press Council of India's national award for excellence in journalism under the gender based reporting category in 2019 and the Laadli Media award (gender sensitivity -2024). A recipient of the Lokmat journalism award (gender category-2022), she was also shortlisted for the RedInk awards for excellence in journalism-2021. Her debut book At The Wheel Of Research, an exclusive biography of Dr Soumya Swaminathan the inaugural chief scientist of World Health Organisation was also nominated in the Popular Choice Category of JK Paper AUTHER awards. She has also secured competitive fellowships including the Laadli Media Fellowship (2022), the Survivors Against TB – New Research in TB Media Fellowship (2023) and is part of the prestigious 2025 India Cohort of the WomenLift Health Leadership Journey.” Recent Notable Articles (Late 2025) 1. Cancer & Specialized Medical Care "Tata Memorial finds way to kill drug-resistant cancer cells" (Nov 26, 2025): Reporting on a breakthrough for triple-negative breast cancer, one of the most aggressive forms of the disease. Discipline, diet and purpose; How a 97-year-old professor defies ageing'' (Nov 15, 2025) Report about Prof Gururaj Mutalik, the first Head of Department at Pune's B J Government Medical College who at 97 credits his longevity to healthy habits and a strong sense of purpose. 2. Environmental Health (The "Breathless Pune" Series) Long-term exposure even to 'moderate' air leads to chronic heart, lung, kidney issues" (Nov 26, 2025): Part of an investigative series highlighting that even "safe" pollution levels are damaging to vital organs. "For every 10 µg/m3 increase in PM2.5 level, there was 6-8% jump in medicine sales" (Nov 23, 2025): Using commercial data to prove the direct link between air quality and respiratory illnesses in Pune. 3. Lifestyle & Wellness News "They didn't let cancer, diabetes and heart disease stop them from travelling" (Dec 22, 2025): A collaborative piece featuring survivors who share practical tips for traveling with chronic conditions. At 17, his BP shot up to 200/120 mmHG; Lancet study flags why child and teen hypertension doubled between 2000 and 2020'' (Nov 12,2025)--A report that focusses on 17-year-old-boy's hypertensive crisis and reflects the rising global trend of high blood pressure among children and adolescents. 4. Scientific Recognition & Infrastructure For promoting sci-comm, gender diversity: IUCAA woman prof highlighted in Nature" (Nov 25, 2025): Covering the global recognition of Indian women scientists in gender studies and physics. Pune researchers find a spiral galaxy like the Milky Way from early universe'' (December 3, 2025)- A report on how Indian researchers discovered a massive galaxy that existed when the universe was just 1.5 billion years old , one of the earliest to have been observed so far. Signature Beat: Health, Science & Women in Leadership Anuradha is known for her COVID-19 reportage, where she was one of the first journalists to provide detailed insights into the Covishield and Covaxin trials. She has a dedicated interest in gender diversity in health and science, often profiling women researchers who are breaking the "leaky pipeline" in STEM fields. Her writing style is scrupulous, often featuring interviews with top-tier scientists and health experts from various institutions. ... Read More

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