Will the universe keep expanding forever, or slow down and collapse? A University of Hawaiʻi at Mānoa researcher contributed to the creation of the largest standardized collection of exploding stars, offering new clues that dark energy—which makes up about 70% of the universe and is thought to drive its accelerating expansion—might change over time.
The study, published in The Astrophysical Journal, used light from 2,087 Type Ia (pronounced “one A”) supernovae. These are powerful explosions that occur when certain types of stars die, and because they all explode in similar ways, scientists can use them like cosmic measuring sticks. Astronomers call these stellar explosions “standard candles” because their brightness is predictable, mimicking identical light bulbs scattered across the cosmos, making them perfect for measuring vast distances in space.
These explosions previously helped reveal in 1998 that the universe’s expansion is speeding up, a discovery that introduced the idea of dark energy and later earned a Nobel Prize. Since then, different experiments around the world have gathered supernova data using various tools and methods. To make the data easier to compare, researchers from the international Supernova Cosmology Project created a new dataset called Union3. It corrects for differences in how the data was collected, allowing scientists to study the universe’s expansion more precisely.
Dark energy, predicting the future of the universe
The updated analysis showed small hints that dark energy may not be constant, which challenges the current leading model based on Albert Einstein’s theory. That model assumes dark energy stays the same over time.
If dark energy changes, it could affect predictions about the future of the universe, including whether it expands forever or eventually slows down. The findings match results from another project that used a different method to study how galaxies are spread out in space, adding weight to the possibility that dark energy might evolve.
The research was a collaboration among scientists from UH, Lawrence Berkeley National Laboratory and institutions around the world. It also used computing power from UH’s high-performance cluster, Koa.
“This project shows how Hawaiʻi’s expertise and computing power can help answer some of the biggest questions in the universe,” said David Rubin, lead author, associate professor in the UH Mānoa Department of Physics and Astronomy and a leading member of the Supernova Cosmology Project. “It’s exciting that our work from Hawaiʻi is part of a global effort to unlock the secrets of dark energy.”
The Department of Physics and Astronomy is housed in UH Mānoa’s College of Natural Sciences.
For more, see this Lawrence Berkeley National Laboratory story.