{"id":333291,"date":"2025-08-10T14:06:13","date_gmt":"2025-08-10T14:06:13","guid":{"rendered":"https:\/\/www.europesays.com\/uk\/333291\/"},"modified":"2025-08-10T14:06:13","modified_gmt":"2025-08-10T14:06:13","slug":"signs-that-dark-energy-varies-over-time-pile-up-raising-questions-about-the-fate-of-the-cosmos","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/uk\/333291\/","title":{"rendered":"Signs that dark energy varies over time pile up, raising questions about the fate of the cosmos!"},"content":{"rendered":"

A team of researchers\u2014including Nobel laureate Saul Perlmutter, who first revealed the universe\u2019s accelerated expansion\u2014has developed a more rigorous way to study dark energy. Their new results add weight to the idea that the fate of our observable cosmos may need reevaluation.<\/strong><\/p>\n

In the late 1990s, teams used Type Ia supernovae<\/a><\/strong> to probe cosmic expansion, expecting a slowdown. Instead, they found the universe speeding up\u2014and earned the 2011 Nobel Prize. <\/p>\n

Building on Jayant Narlikar\u2019s cosmology lectures, scientists reintroduced Einstein\u2019s cosmological constant, \u039b, as a mysterious energy. WMAP and Planck measurements refined this picture, showing we live in a nearly flat, Euclidean universe\u2014perhaps even a torus\u2014with eternal expansion leading to a \u201cheat death.\u201d<\/p>\n<\/p>\n

Three videos explaining dark energy. Here is video 1. \u00a9 PBS Space Time<\/p>\n

A Big Crunch driven by dark energy?<\/p>\n

Since our destiny ties to the cosmos\u2019s, astrophysicists want better constraints on \u039b. Some theories predict that \u039b might vary over time\u2014shifting from repulsive (driving expansion) to attractive<\/a><\/strong><\/strong>, triggering a cosmic contraction or Big Crunch, then a rebound Big Bang.<\/p>\n

To test this, Perlmutter\u2019s Supernova Cosmology Project team reanalyzed SN Ia data. Their open-access paper on arXiv shows hints\u2014echoing recent studies\u2014that the value of \u039b (and the dark energy it represents) may be decreasing<\/strong> over time.<\/p>\n

\"\"<\/p>\n

In 2011, a sky survey detected a Type Ia supernova, SN 2011fe, in the Pinwheel Galaxy, about 21 million light-years away. \u00a9 B. J. Fulton, Palomar Transient Factory<\/p>\n

Remember, SN Ia are explosions of white dwarfs packing the Sun\u2019s mass into a Earth-sized volume. They shine so bright they\u2019re visible across billions of light-years, with nearly uniform peak luminosity\u2014making them perfect \u201cstandard candles.\u201d By comparing their apparent brightness and redshift<\/a><\/strong>, we map galactic distances and track changes in the universe\u2019s expansion rate.<\/p>\n<\/p>\n

Here is Video II. \u00a9 PBS Space Time<\/p>\n

A more rigorous technique for analyzing cosmic expansion<\/p>\n

Perlmutter\u2019s group focused on calibrating measurements for 2,087 supernovae from 24 datasets, spanning roughly 7 billion years of cosmic history. As Berkeley Lab explains, they used a hierarchical Bayesian model\u2014a sophisticated statistical method that better handles uncertainties by integrating partial information and error probabilities.<\/p>\n

For instance, this approach accounts for a telescope<\/strong><\/a>\u2019s filter drift over time, which can alter supernova brightness. This flexibility boosts precision\u2014something older techniques struggled to achieve. Soon, this framework will incorporate the torrent of new SN Ia detections expected from the Vera Rubin Observatory.<\/p>\n<\/p>\n

Here is Video III. \u00a9 PBS Space Time<\/p>\n

\"\"<\/p>\n

\t\t\t Laurent Sacco <\/p>\n

\n Journalist <\/p>\n

Born in Vichy in 1969, I grew up during the Apollo era, inspired by space exploration, nuclear energy, and major scientific discoveries. Early on, I developed a passion for quantum physics, relativity, and epistemology, influenced by thinkers like Russell, Popper, and Teilhard de Chardin, as well as scientists such as Paul Davies and Haroun Tazieff.<\/p>\n

I studied particle physics at Blaise-Pascal University in Clermont-Ferrand, with a parallel interest in geosciences and paleontology, where I later worked on fossil reconstructions. Curious and multidisciplinary, I joined Futura to write about quantum theory, black holes, cosmology, and astrophysics, while continuing to explore topics like exobiology, volcanology, mathematics, and energy issues.<\/p>\n

I\u2019ve interviewed renowned scientists such as Fran\u00e7oise Combes, Abhay Ashtekar, and Aur\u00e9lien Barrau, and completed advanced courses in astrophysics at the Paris and C\u00f4te d\u2019Azur Observatories. Since 2024, I\u2019ve served on the scientific committee of the Cosmos prize. I also remain deeply connected to the Russian and Ukrainian scientific traditions, which shaped my early academic learning.<\/p>\n

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