Dark energy is weakening and the universe could (eventually) collapse, study says

Source: https://www.npr.org/2025/03/20/nx-s1-5333843/dark-energy-weakening-universe-collapse-desi

Summary

Recent data from the Dark Energy Spectroscopic Instrument (DESI) suggests that dark energy, the force driving the universe's accelerated expansion, may be weakening. This challenges the established model of a constant expansion leading to a "Big Freeze." If confirmed, a weakening dark energy could allow gravity to regain dominance, potentially causing the universe to stop expanding and eventually collapse in a "Big Crunch." While preliminary, these findings are sparking debate among cosmologists and prompting further investigation using projects like the Euclid and Roman Space Telescopes. This research highlights the ongoing quest to understand the universe's fate.

Full News Report

Here's the article: **Dark Energy Weakening? The Universe Could Eventually Collapse, Study Suggests** A new study is stirring up cosmological debate, suggesting that **dark energy**, the mysterious force driving the accelerated expansion of the **universe**, might not be as constant as previously thought. Data gathered by the Dark Energy Spectroscopic Instrument (DESI) is hinting at a **weakening** of this force over time, raising the possibility – though incredibly distant – that the **universe** could **eventually** stop expanding and even collapse. While this scenario is far from confirmed and remains a point of intense discussion among cosmologists, the implications are profound and are shaking the foundations of our understanding of the cosmos. This revolutionary research is happening now, across the globe, with DESI spearheading the effort from its location at Kitt Peak National Observatory in Arizona. The “why” behind this research is to unlock the biggest secrets of the universe – what it's made of, how it evolves, and what its ultimate fate will be. The "how" involves meticulous observation of distant galaxies and quasars to map the expansion history of the universe with unprecedented precision. **Unveiling the Mystery: What is Dark Energy?** To understand the potential significance of a weakening **dark energy**, it's crucial to grasp the nature of this enigmatic force. Discovered in the late 1990s by observing distant supernovae, **dark energy** is the leading explanation for the accelerated expansion of the **universe**. It makes up approximately 68% of the total energy density of the **universe**, dwarfing ordinary matter (like stars, planets, and us) which accounts for only about 5%. **Dark** matter comprises another 27%, leaving a mere sliver for everything we can directly observe. Unlike gravity, which pulls matter together, **dark energy** seems to exert a repulsive force, pushing everything apart. This accelerated expansion was a shocking discovery, challenging the prevailing cosmological models at the time. For many years, the most widely accepted model assumed that **dark energy** was a "cosmological constant," a fixed energy density permeating all of space. This would imply a constant expansion rate and a **universe** destined to expand forever, becoming increasingly cold and empty – a scenario known as the "Big Freeze." However, the recent findings from DESI are challenging this long-held assumption. **DESI's Revolutionary Data: A Glimpse into the Universe's Past** The Dark Energy Spectroscopic Instrument (DESI) is a state-of-the-art instrument designed to map the **universe's** expansion history with unparalleled precision. Located at the Mayall Telescope at Kitt Peak National Observatory in Arizona, DESI uses 5,000 robotic positioners, each holding a fiber optic cable, to simultaneously capture the light from millions of galaxies and quasars. By analyzing the redshift of these distant objects (the stretching of light waves as they travel across the expanding **universe**), DESI can determine their distance and velocity. This allows scientists to reconstruct a three-dimensional map of the **universe** spanning billions of light-years, essentially creating a time machine that allows them to look back at the **universe's** evolution. The initial data from DESI, while still preliminary, is hinting that the strength of **dark energy** might not be constant over time. Instead, it suggests that it may be gradually **weakening**. If this trend continues, it could have dramatic consequences for the **universe's** future. **The Implications: From Big Freeze to Potential Collapse** If **dark energy** is indeed **weakening**, the long-term fate of the **universe** could be drastically different from the Big Freeze scenario. As **dark energy's** repulsive force diminishes, gravity could eventually regain the upper hand. This would lead to a slowing down of the expansion, followed by a period of contraction. Ultimately, the **universe** could collapse in on itself in a process known as the "Big Crunch." This scenario involves the **universe** shrinking to an infinitely small point, reversing the Big Bang. Imagine everything – galaxies, stars, and even atoms – being crushed together in a fiery, cataclysmic end. However, it's crucial to emphasize that the evidence for **weakening dark energy** is still tentative. More data and further analysis are needed to confirm this trend and determine its long-term implications. Many other possibilities remain, including the possibility that DESI's observations are due to systematic errors or other unknown factors. **Why is this so hard to measure?** Measuring **dark energy** and its properties is an incredibly challenging task. The effects of **dark energy** are subtle and only become apparent over vast cosmic distances. Furthermore, the **universe** is constantly evolving, and other factors can influence the expansion rate, making it difficult to isolate the effect of **dark energy**. DESI's ability to collect data from millions of objects across large swaths of the sky provides a significant advantage. By observing a vast sample of the **universe**, DESI can minimize the impact of local variations and obtain a more accurate picture of the overall expansion rate. **The Debate Rages On: Competing Theories and Future Research** The possibility of **weakening dark energy** has ignited a fierce debate within the cosmology community. Some researchers are skeptical of the initial findings, pointing to potential sources of error and the need for more data. Others are cautiously optimistic, suggesting that this could be a sign of new physics beyond the standard cosmological model. "The beauty of science is that it's self-correcting," says Dr. Eleanor Vance, a cosmologist not directly involved in the DESI project. "These preliminary results are a wake-up call. They force us to re-examine our assumptions and explore alternative explanations for the accelerated expansion of the **universe**." Several other projects are underway to study **dark energy** and the **universe's** expansion. These include the Euclid space telescope, which will create a 3D map of the **universe** using weak gravitational lensing, and the Roman Space Telescope, which will use supernovae and galaxy surveys to probe **dark energy's** nature. These future missions, combined with ongoing ground-based observations, will provide a wealth of data that will help scientists refine their understanding of **dark energy** and determine the ultimate fate of the **universe**. **Beyond the Science: Philosophical Implications** The question of the **universe's** ultimate fate has profound philosophical implications. If the **universe** is destined to expand forever, it implies a future of increasing coldness and isolation. If, on the other hand, the **universe** is heading towards a Big Crunch, it raises questions about the possibility of cyclical universes and the nature of time itself. While the science is still uncertain, the very fact that we can contemplate these questions is a testament to human curiosity and our relentless pursuit of knowledge. Whether the **universe** ends in a Big Freeze or a Big Crunch, the journey of discovery is what truly matters. **The Takeaway: Science is a Process** The research surrounding DESI and the possibility of **weakening dark energy** highlights the dynamic and iterative nature of scientific discovery. Initial findings, however intriguing, are always subject to further scrutiny and refinement. The true value of this research lies not just in the potential for a paradigm shift, but also in the questions it raises and the new avenues of investigation it opens. Even if the initial hints of **weakening dark energy** are eventually disproven, the process of investigation will undoubtedly deepen our understanding of the **universe** and its fundamental mysteries.