I like this idea (Dark Flow), it actually fits into the cyclic cosmology model I agree with (Steinhardt, Ilyas), which has parts of the universe expanding while others contract and vice versa. Effectively, these separate areas become their own universes. In the paper I read the analogy was a ball with kinetic energy rolling up a hill, as it rolls up that hill the kinetic energy gets converted to potential energy. Once at the top of the hill, all the kinetic energy has now been converted to potential energy and it briefly pauses there and then starts to roll downhill with the potential energy being converted back to kinetic energy. This is the cyclic model of the universe, with many peaks and valleys. Each big bang or big bounce happens when the universe reaches a valley and not all of the potential energy has been converted back to kinetic energy and the universe starts to make the same uphill climb again. In their paper they stated that in their mathematical model each cycle creates a larger universe than the previous one (a smaller cosmological constant would be the reason why) and eventually the cycle will become so large that the universe will no longer contract (you can call this *heat death* but it's also possible that a tiny part of this *dying* universe will create a new Big Bang (perhaps inside a spinning Kerr black hole with a ring singularity) and with the cosmic *dna* of the parent universe will inherit many of the qualities of the parent universe.
The size of this cycle has been set at 1 trillion years and we may have just found evidence that dark energy is in the process of reversing and that the universe may be on the cusp of slowing down expansion (according to this contraction will start in approximately 65 million years, a very interesting number.)
New evidence that dark energy is evolving
Dark energy, the mysterious force thought to make up some 70% of the universe, is considered by many scientists to be an unchanging cosmological constant. But a new data release from the groundbreaking Dark Energy Spectroscopic Instrument hints that may not be the case. The researchers said yesterday that new measurements of some 15 million galaxies and quasars suggest dark energy in the universe is getting weaker.
https://earthsky.org/space/desi-new-data-hints-dark-energy-in-the-universe-is-evolving/?mc_cid=29fc67825e&mc_eid=f195ba0afd
https://noirlab.edu/public/news/noirlab2513/
A new data release hints dark energy may be weakening
On March 19, 2025, scientists announced the results of a new analysis using the Dark Energy Spectroscopic Instrument (DESI), mounted on the Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory in Arizona. With the first three years of data involving some 15 million galaxies and quasars, they’ve found hints that dark energy changes over time. Dark energy, which makes up some 70% of the universe, is a mysterious force that drives the accelerating expansion of our universe.
DESI helped create the largest yet 3D map of our universe. With this map, scientists could see how dark energy has influenced our universe over the past 11 billion years. And indeed, what they found was that this influence has not been a cosmological constant, but it has changed over time.
The DESI collaboration published their peer-reviewed findings on March 19, 2025, in multiple papers that you can read on the DESI collaboration website. In addition, the scientists also presented their findings at the American Physical Society’s Global Physics Summit in Anaheim, California.
2025 EarthSky lunar calendar is available now. A unique and beautiful poster-sized calendar with phases of the moon for every night of the year. Get yours today!
Dark energy may be weakening over time
The findings draw upon the data from DESI and earlier studies of the cosmic microwave background, supernovas and weak lensing. The press release said:
Taken alone, DESI’s data are consistent with our standard model of the universe: Lambda CDM, where CDM is cold dark matter and lambda represents the simplest case of dark energy, where it acts as a cosmological constant. However, when paired with other measurements, there are mounting indications that the impact of dark energy may be weakening over time and that other models may be a better fit.
In order for scientists to declare a discovery, however, their findings should reach a 5-sigma level. This is the gold standard for the threshold of discovery. At the moment, the analysis of the new data is around 2.8 to 4.2 sigma.
An animation of the largest 3D map of our universe. It traces the location of matter, with Earth at the center and the darker blues denoting the most distant objects. Animation via DESI Collaboration/ DOE/ KPNO/ NOIRLab/ NSF/ AURA/ R. Proctor.
DESI data available to the public
DESI can look at 5,000 galaxies at one time, overall. Additionally, it tracks the influence of dark energy by noting where matter exists across our universe. There are patterns left behind from the early universe known as Baryon Acoustic Oscillations (BAO). The patterns in these oscillations provide scientists with a ruler. And the ruler allows scientists to measure the peaks in the oscillating waves and how much they get stretched over time.
Michael Levi, DESI director and a scientist at Berkeley Lab, said:
Whatever the nature of dark energy is, it will shape the future of our universe. It’s pretty remarkable that we can look up at the sky with our telescopes and try to answer one of the biggest questions that humanity has ever asked.
The datasets are now available to astronomers and the public alike. Overall, this wealth of data has information on 18.7 million objects. That’s about 4 million stars, 13.1 million galaxies and 1.6 million quasars, specifically. Eventually, DESI will provide us with precise distances to millions of galaxies.
Chris Davis, NSF program director for NSF NOIRLab, said:
These are remarkable results from an incredibly successful project. The potent combination of the National Science Foundation’s Mayall Telescope and Department of Engery’s Dark Energy Spectroscopic Instrument shows the benefits of federal agencies working together on fundamental science that improves our understanding of the universe.
Bottom line: A new data release from the Dark Energy Spectroscopic Instrument hints that the universe’s dark energy is not constant and may be weakening over time.
Source: DESI DR2 Results II: Measurements of Baryon Acoustic Oscillations and Cosmological Constraints
https://data.desi.lbl.gov/public/papers/y3/KP.DR2.BAO.pdf
https://noirlab.edu/public/news/noirlab2513/
Latest Dark Energy Survey Data Suggest Possible Variations in Dark Energy Over Time
DES spots potential inconsistencies in the standard model of cosmology, supporting a theory of evolving dark energy that could alter the foundations of physics
19 March 2025
Víctor M. Blanco 4-meter Telescope
A groundbreaking new study using the Dark Energy Survey (DES) final datasets suggests potential inconsistencies in the standard cosmological model, known as ΛCDM. If confirmed, these findings could fundamentally alter our understanding of the Universe. DES was conducted using the 570-megapixel Department of Energy-fabricated Dark Energy Camera (DECam), mounted on the U.S. National Science Foundation Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory in Chile, a Program of NSF NOIRLab.
The ΛCDM (Lambda-CDM) model has been the foundation of modern cosmology for some time now, successfully describing large-scale structures in the Universe. It proposes that 95% of the cosmos is composed of dark matter (25%) and dark energy (70%) — mysterious substances whose nature remains unknown. Only 5% of the Universe consists of ordinary matter.
Dark energy, represented by the cosmological constant (Λ), is thought to drive the accelerating expansion of the Universe, maintaining a constant energy density over time. However, new results from the Dark Energy Survey (DES), presented today in a paper appearing on arXiv and in talks at the American Physical Society’s Global Physics Summit in Anaheim, California, hint at a deviation from this assumption, suggesting that dark energy might evolve over time. These findings align with previous studies, reinforcing their significance.
The DES is an international collaboration comprising more than 400 scientists from over 25 institutions, led by the U.S. Department of Energy’s Fermi National Accelerator Laboratory. The DES was conducted using the 570-megapixel Department of Energy-fabricated Dark Energy Camera (DECam), mounted on the U.S. National Science Foundation (NSF) Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO) in Chile, a Program of NSF NOIRLab. By taking data on 758 nights across six years, DES scientists mapped an area almost one-eighth of the entire sky. The project employs multiple observational techniques, including supernova measurements, galaxy clustering analysis, and weak gravitational lensing, to study dark energy.
Two key DES measurements — Baryon Acoustic Oscillations (BAO) and distance measurements of exploding stars (Type Ia supernovae) — track the Universe’s expansion history. BAO refers to a standard cosmic ruler formed by sound waves in the early Universe, with peaks spanning approximately 500 million light-years. Astronomers can measure these peaks across several periods of cosmic history to see how dark energy has stretched the scale over time.
Santiago Avila from the Centre for Energy, Environmental and Technological Research (CIEMAT) in Spain, who was responsible for the BAO analysis in DES, says, “By analyzing 16 million galaxies, DES found that the measured BAO scale is actually 4% smaller than predicted by ΛCDM.”
Type Ia supernovae serve as 'standard candles', meaning they have a known intrinsic brightness. Therefore, their apparent brightness, combined with information about their host galaxies, allows scientists to make precise distance calculations. In 2024 DES published the most extensive and detailed supernova dataset to date, providing highly accurate measurements of cosmic distances. These new findings from the combined supernovae and BAO data independently confirm the anomalies seen in the 2024 supernova data.
By integrating DES measurements with cosmic microwave background data, researchers inferred the properties of dark energy — and the results suggest a time-evolving nature. If validated, this would imply that dark energy, the cosmological constant, is not constant after all, but a dynamic phenomenon requiring a new theoretical framework.
“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.”
Although the current results are not yet definitive, upcoming analyses incorporating additional DES probes — such as galaxy clustering and weak lensing — could strengthen the evidence. Similar trends have emerged from other major cosmological projects, including the Dark Energy Spectroscopic Instrument (DESI), raising anticipation within the scientific community [1].
“These results represent years of collaborative effort to extract cosmological insights from DES data,” says Jessie Muir of the University of Cincinnati. “There is still much to learn, and it will be exciting to see how our understanding evolves as new measurements become available.”
The final DES analysis, expected later this year, will incorporate additional cosmological probes to cross-check findings and refine constraints on dark energy. The scientific community eagerly awaits these results, as they could pave the way for a paradigm shift in cosmology.
Notes
[1] This press release describes the DESI Collaboration’s analysis of the survey’s first three years of collected data, which also found hints of a time-evolving dark energy.
More information
These results are presented by the DES Collaboration.
NSF NOIRLab, the U.S. National Science Foundation center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), NSF Kitt Peak National Observatory (KPNO), NSF Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and NSF–DOE Vera C. Rubin Observatory (in cooperation with DOE’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona.
The scientific community is honored to have the opportunity to conduct astronomical research on I’oligam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence of I’oligam Du’ag to the Tohono O’odham Nation, and Maunakea to the Kanaka Maoli (Native Hawaiians) community.
Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, Funding Authority for Funding and Projects in Brazil, Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro, Brazilian National Council for Scientific and Technological Development and the Ministry of Science and Technology, the German Research Foundation and the collaborating institutions in the Dark Energy Survey.
Based in part on data acquired at the Anglo-Australian Telescope for the Dark Energy Survey by OzDES. We acknowledge the traditional custodians of the land on which the AAT stands, the Gamilaraay people, and pay our respects to elders past and present.
Fermilab is America’s premier national laboratory for particle physics and accelerator research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance LLC. Visit Fermilab’s website at www.fnal.gov and follow us on Twitter at @Fermilab.
The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
Links
Read the paper: Dark Energy Survey: implications for cosmological expansion models from the final DES Baryon Acoustic Oscillation and Supernova data
Visit the Dark Energy Survey webpage
Photos of the Víctor M. Blanco 4-meter Telescope
Videos of the Víctor M. Blanco 4-meter Telescope
Photos of the Dark Energy Camera
NOIRLab Stories Blog: Two Cosmological Surveys Strengthen Hints That Standard Model of Cosmology Is Wrong
Check out other NOIRLab Science Releases
https://noirlab.edu/public/blog/two-cosmological-surveys/
