{"id":188958,"date":"2025-10-04T05:00:10","date_gmt":"2025-10-04T05:00:10","guid":{"rendered":"https:\/\/www.newsbeep.com\/au\/188958\/"},"modified":"2025-10-04T05:00:10","modified_gmt":"2025-10-04T05:00:10","slug":"scientists-warn-the-universe-could-end-in-a-big-crunch-heres-when-it-might-happen","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/au\/188958\/","title":{"rendered":"Scientists Warn the Universe Could End in a ‘Big Crunch’\u2014Here\u2019s When It Might Happen"},"content":{"rendered":"

When gazing at the night sky, it feels timeless, with seemingly limitless stars glimmering as they have for billions of years. However, a new study suggests our universe may not be destined to continue expanding forever. Instead, it\u00a0may eventually collapse back in on itself, ending in a dramatic \u201cbig crunch<\/a>\u201d roughly 20 billion years from now.<\/p>\n

The study, published in Journal of Cosmology and Astroparticle Physics<\/a> and co-authored by researchers at Cornell University, the Donostia International Physics Center in Spain, and the Tsung-Dao Lee Institute in Shanghai, proposes that an exotic form of dark energy known as an \u201cultralight axion\u201d combined with a negative cosmological constant may dictate the universe\u2019s fate.\u00a0<\/p>\n

The team\u2019s analysis of the latest Dark Energy Survey<\/a> (DES) and Dark Energy Spectroscopic Instrument <\/a>(DESI) data suggests a surprisingly finite cosmic lifetime, roughly twice as long as the 13.8 billion years that have already elapsed since the Big Bang.<\/p>\n

\u201cFor the last 20 years, people believed that the cosmological constant is positive, and the universe will expand forever,\u201d co-author and professor of physics at Cornell, Dr. Henry Tye, said in a press release<\/a>. \u201cThe new data seem to indicate that the cosmological constant is negative, and that the universe will end in a big crunch.\u201d<\/p>\n

Since the late 1990s, cosmologists have understood that the universe\u2019s expansion is accelerating, a discovery attributed to a mysterious force called dark energy<\/a>. The simplest model, known as \u039bCDM, or Lambda-CDM model<\/a>, assumes a positive cosmological constant (\u039b) and predicts infinite expansion. However, DES and DESI\u2019s high-precision measurements have unsettled that picture. They indicate the dark energy equation of state may differ significantly from the textbook value of w = \u22121.<\/p>\n

Enter the \u201caxion dark energy\u201d (aDE) model explored in this new study. By combining a negative cosmological constant with an ultralight axion field, a hypothetical particle often invoked in string theory, the model can reproduce DES and DESI\u2019s results more accurately than the standard \u039bCDM. Significantly, it implies the universe\u2019s expansion will one day halt and reverse.<\/p>\n

\u201cWith the best-fit values for the parameters of the model, we find that the lifespan of the universe is 33.3 billion years; that is, the universe will end in about 20 billion years,\u201d the researchers note.\u00a0<\/p>\n

That estimate places the onset of contraction, when the cosmic scale factor reaches its maximum, about 11 billion years from now, followed by a rapid \u201cbig crunch\u201d phase lasting roughly a quarter of the remaining lifespan.<\/p>\n

Researchers emphasize that DESI\u2019s northern-hemisphere data and DES\u2019s southern-hemisphere results converge at a 4.2-sigma level on w \u2260 \u22121. That\u2019s strong enough to warrant serious attention, though still short of physics\u2019 gold standard of 5-sigma certainty. If future surveys confirm these measurements, the aDE model could supplant \u039bCDM as the dominant cosmological framework.<\/p>\n

The axion in this model behaves differently at different times in cosmic history<\/a>. In the early universe, it\u2019s effectively frozen, mimicking a cosmological constant. Later, as the Hubble parameter falls below the axion\u2019s mass, the field \u201crolls\u201d down its potential, converting vacuum energy into matter-like energy density. This evolution naturally shifts the dark energy<\/a> equation of state above \u22121, aligning with DESI\u2019s observations.<\/p>\n

However, the real twist comes from the negative cosmological constant. In the paper\u2019s approximate model, once the scale factor hits its maximum value, predicted at a = 1.69, the Hubble parameter crosses zero. It turns negative, signaling the onset of the \u201cbig crunch.\u201d The universe\u2019s final act accelerates as matter and radiation compress, potentially triggering an era of intense black hole<\/a> mergers before all structure collapses into a singularity.<\/p>\n

For now, the aDE model remains a hypothesis, albeit one with intriguing statistical support. The authors openly acknowledge the significant decline in their parameter space and the need for improved data.\u00a0<\/p>\n

\u201cIt is crucial that the DES\/DESI observation is confirmed and the aDE model is rigorously tested,\u201d the researchers write. \u201cFortunately, a number of projects measuring different aspects of dark energy are forthcoming in the near future.\u201d\u00a0<\/p>\n

These future projects include next-generation surveys of baryon acoustic oscillations, supernovae<\/a>, and cosmic microwave background polarization, all of which can tighten constraints on w(a), the dark energy equation of state over time. If, indeed, the signal for a negative \u039b holds, cosmology textbooks may need a significant revision.<\/p>\n

Beyond observational cosmology, the study has implications for deeper theoretical ideas. String theory<\/a> has long hinted that building a stable vacuum with positive \u039b, like today\u2019s dark energy, is difficult, whereas vacua with negative \u039b arise more naturally.\u00a0<\/p>\n

In that sense, the aDE model dovetails with the so-called \u201cstring theory landscape\u201d picture, which envisions a multiverse of possible vacua. Our universe might simply be heading toward a more generic state.<\/p>\n

The paper also highlights the \u201caxiverse,\u201d or the notion that multiple ultralight axions of different masses populate the cosmos. The researchers note that adding an even lighter axion could further lower \u039b, reinforcing the big crunch scenario. These insights, if verified, could provide rare observational windows into the otherwise abstract mathematics of string theory.<\/p>\n

Although 20 billion years sounds unimaginably distant, the paper draws an interesting local connection. Our own Milky Way<\/a> is predicted to collide with the Andromeda galaxy<\/a> within about 4 to 10 billion years.\u00a0<\/p>\n

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Depending on the timing of the universe\u2019s turnaround, the two galaxies\u2019 merger may occur under very different cosmic conditions than previously assumed. In the extreme scenario, the universe could already be slowing its expansion as the collision unfolds.<\/p>\n

And while the big crunch phase is brief on cosmic timescales, it would be catastrophic. As the scale factor shrinks, matter density skyrockets, potentially leading to the formation of giant black holes that \u201cshield\u201d or \u201chide\u201d the final singularity.\u00a0<\/p>\n

The authors refrain from speculating on whether quantum effects<\/a> might enable a bounce into a new cycle. Still, they caution that any such reincarnation would produce a universe very unlike ours.<\/p>\n

The new study doesn\u2019t mean the end is necessarily near. Humanity still has at least 20 billion years before cosmic contraction begins, if the model is correct. However, it does underscore the dynamic and uncertain nature of our understanding of dark energy<\/a>. For decades, \u039bCDM seemed invulnerable. Yet, now high-precision data are cracking its foundations.<\/p>\n

If confirmed, the aDE model\u2019s prediction of a finite cosmic lifespan would mark one of the most profound shifts in cosmology since the discovery of the universe\u2019s accelerated expansion. It suggests not an endless, cold fade into darkness but a massive, fiery big crunch back to the conditions of the Big Bang<\/a>.\u00a0<\/p>\n

\u201cFor any life, you want to know how life begins and how life ends \u2013 the end points,\u201d Dr. Tye said. \u201cFor our universe, it\u2019s also interesting to know, does it have a beginning? In the 1960s, we learned that it has a beginning. Then the next question is, \u2018Does it have an end?\u2019 <\/p>\n

\u201cFor many years, people thought it would continue indefinitely,\u201d Tye concludes. \u201cIt\u2019s good to know that, if the data holds up, the universe will have an end.\u201d <\/p>\n

Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter:\u00a0@LtTimMcMillan. \u00a0<\/a>Tim can be reached by email:\u00a0tim@thedebrief.org<\/a>\u00a0or through encrypted email:\u00a0LtTimMcMillan@protonmail.com<\/a>\u00a0<\/p>\n

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