Analysis of 2,884 Exploding Stars Suggests Dark Energy May Vary Over Time

An international research team, led by scientists at the University of Queensland’s School of Mathematics and Physics, has compiled the largest collection of exploding white dwarf stars ever, totaling 2,884 Type Ia supernovae. This extensive analysis provides fresh evidence that dark energy, the mysterious force accelerating the Universe’s expansion, may change over time. These findings challenge a central assumption of modern cosmology and could help scientists better understand how the Universe evolves.

PhD candidate Ryan Camilleri stated that this project establishes a new international standard for supernova cosmology. By rebuilding three decades of astronomical observations into a single, consistent framework, and combining this data with other cosmic measurements—including relic light from the Big Bang and maps of how galaxies are distributed through space—researchers created their most detailed picture yet of how cosmic expansion has changed. Camilleri noted that instead of confirming the standard model of cosmology, which assumes dark energy is fixed and unchanging, they found more evidence that dark energy may change over time.

The new collection integrates historical supernova measurements with findings from the Dark Energy Survey (DES) published in 2024. To make observations collected over different periods directly comparable, scientists revisited older data using updated analytical methods, leveraging advances in understanding supernova behavior to improve consistency and accuracy. The team also meticulously accounted for differences among the telescopes used, cosmic dust, galaxy masses, and more subtle effects like gravitational lensing, which can influence the light astronomers receive from distant supernovae and thus affect distance measurements.

Astrophysicist Professor Tamara Davis highlighted that the expanded dataset represents an important advance in efforts to understand the nature of dark energy. She noted that their supernova data from DES in 2024 first showed hints that dark energy may be time-varying, and this new compilation also sees a deviation from the standard model, although in a slightly different direction. Importantly, similar results from the Dark Energy Spectroscopic Instrument (DESI) found hints of variations in dark energy in its surveys of relic sound waves from the early Universe. This means two completely independent measurements have found hints of time variation in dark energy, challenging the standard model that dark energy doesn't change.

Understanding dark energy could have implications extending far beyond the expansion of the Universe. Researchers believe that learning more about its behavior might also provide insights into one of the greatest unresolved problems in theoretical physics: reconciling gravity with quantum physics. Future supernova surveys, such as the Dark Energy Bedrock All-Sky Supernova program (DEBASS), are planned to expand the dataset, identifying hundreds of supernovae closer to Earth to provide further measurements to investigate the Universe’s expansion and test whether dark energy truly changes over time.

What to watch: Further research from DEBASS and DESI to confirm the variability of dark energy.

Editor's note: The draft provides a thorough and accurate summary of the scientific research and its cosmological implications as detailed in the source.