An international research team led by the University of Queensland compiled observations of 2,884 Type Ia supernovae, the largest collection of exploding white dwarf stars ever assembled. The dataset provides evidence that dark energy, the force driving the Universe's accelerating expansion, may vary over time rather than remain constant as the standard model of cosmology assumes.
PhD candidate Ryan Camilleri unified three decades of supernova measurements into a single framework. The team combined Type Ia supernova data with observations from the Dark Energy Survey published in 2024, as well as relic light from the Big Bang and galaxy distribution maps.
Scientists revisited older observations using updated analytical methods to make measurements from different periods directly comparable. Advances in understanding supernova behavior improved the consistency and accuracy of decades-old data. The researchers accounted for differences among telescopes, cosmic dust, galaxy masses, and gravitational lensing effects that influence light from distant supernovae.
Camilleri stated: "Instead of confirming the standard model of cosmology which assumes dark energy is fixed and unchanging, we have more evidence that dark energy may change over time."
Professor Tamara Davis noted that the expanded dataset shows a deviation from the standard model. The findings align with separate results from the Dark Energy Spectroscopic Instrument, which found hints of dark energy variations in surveys of relic sound waves from the early Universe.
Davis added that understanding dark energy could provide insights into reconciling gravity with quantum physics. The team plans to expand the dataset using observations from the Dark Energy Bedrock All-Sky Supernova program, which identifies nearby supernovae at closer distances than previous surveys.