Massive exploding stars may have unraveled the mystery of our Universe's end

A new study is raising fresh questions about the fate of the universe. Scientists have long wondered whether the universe will keep expanding forever or eventually slow down and collapse (The Big Rip?). The latest research, published in The Astrophysical Journal, suggests that dark energy, the mysterious force thought to drive the universe’s accelerating expansion, might actually change over time instead of staying constant.

The work is based on the largest standardized collection of Type Ia (pronounced “one A”) supernovae ever put together, with 2087 explosions from 24 different surveys. Type Ia supernovae happen when certain stars reach the end of their lives and explode in a very predictable way. Because their brightness is always about the same, astronomers use them as “standard candles,” like identical light bulbs scattered across space, to measure distances in the universe.

These supernovae were key to the 1998 discovery that the universe’s expansion is speeding up, which led to the idea of dark energy and later earned a Nobel Prize. They remain important because they are common, precise, and can be seen across huge distances, making them one of the best tools for studying the cosmos.

To make the data more reliable, the international Supernova Cosmology Project created a new dataset called Union3. It puts all the supernovae on the same distance scale and updates the way their light curves are analyzed using a method called SALT3, which takes into account the full rest-frame optical spectrum. The researchers also introduced a new statistical framework called UNITY1.5 (Unified Nonlinear Inference for Type-Ia cosmologY). This helps deal with tricky issues like selection effects, outliers, and differences in how the explosions are observed, while keeping uncertainties under control.

The analysis showed weak but noticeable tension, at the level of 1.7σ to 2.6σ, with the standard flat cold dark matter model that assumes dark energy never changes. Instead, the results hint at possible evidence for “thawing” dark energy, where its properties evolve over time (w₀ > −1, wₐ

The findings also line up with results from another project that studied how galaxies are spread out in space, giving more weight to the idea that dark energy might not be uniform.

The study was carried out by researchers from the University of Hawaii at Mānoa, Lawrence Berkeley National Laboratory, and other institutions worldwide. It also used computing power from UH’s high-performance cluster, Koa.

David Rubin, lead author and associate professor in the UH Mānoa Department of Physics and Astronomy, said, “This project shows how Hawaii’s expertise and computing power can help answer some of the biggest questions in the universe. It’s exciting that our work from Hawaii is part of a global effort to unlock the secrets of dark energy.”

The team has released their supernova distances, light-curve fits, and the UNITY1.5 framework to the scientific community. With the number of useful supernovae expected to increase by more than tenfold in the coming years, future studies will face new challenges in keeping uncertainties low. For now, the results add to growing evidence that dark energy may not be as simple as once thought.

Source: University of Hawai'i, IOP Science

This article was generated with some help from AI and reviewed by an editor. Under Section 107 of the Copyright Act 1976, this material is used for the purpose of news reporting. Fair use is a use permitted by copyright statute that might otherwise be infringing.

Source

Hope you enjoyed this news post. Feedback welcome.

Posted Friday 3 October 2025 at 5:04 pm AEST (my time).

News posts... 2023: 5,800+ | 2024: 5,700+ | 2025 (till end of September): 4,533

RIP Matrix