New Model Predicts the End of the Universe Is Certain By David Freeman - October 6, 2025
A provocative new analysis of data from two major astronomical surveys suggests the force driving the expansion of space may be changing over cosmic time. The findings, drawn from the Dark Energy Survey in Chile and the Dark Energy Spectroscopic Instrument in Arizona, challenge the long held idea of a perpetually expanding universe. This is a profound claim that strikes at the heart of modern cosmology. For nearly a century, we have understood the universe to be growing, and for the last two decades, we have believed that growth is accelerating. The notion that this fundamental cosmic motion could not only halt but reverse itself forces a dramatic reevaluation of the past, present, and ultimate future of everything that exists. If this new model is correct, the cosmological constant, the term thought to determine the universe’s ultimate fate, could be negative. Such a reality would set a finite lifespan for the cosmos, replacing the forecast of a cold, empty future with one of a final, cataclysmic collapse.
This potential paradigm shift comes from a detailed study by physicists Hoang Nhan Luu, Yu Cheng Qiu, and Henry Tye. Their model, specifically designed to fit the latest, most precise observational data, proposes a startling and complete timeline for our universe. It suggests that the cosmos, which began in the fires of the Big Bang 13.8 billion years ago, may be roughly halfway through its existence. The current era of accelerated expansion is, in their view, a temporary phase. Their calculations indicate that the universe will continue to expand for another eleven billion years, reaching a maximum size before the cosmic tide turns. From that peak, it would begin a slow, inexorable collapse. In this scenario, the force of gravity, currently overcome by dark energy on the largest scales, would eventually reassert its dominance. Over a further nine billion years of contraction, the universe would shrink until all matter and energy, every star, every galaxy, and every particle, meet again at a single, infinitely dense point, some twenty billion years from now.
The conclusion hinges on high precision measurements of how galaxies and the vast cosmic web of structure have evolved over billions of years. Both the Dark Energy Survey, or DES, and the Dark Energy Spectroscopic Instrument, or DESI, are monumental achievements of modern astronomy. DES spent six years imaging a huge swath of the southern sky from its vantage point in the Chilean Andes, mapping the positions and shapes of hundreds of millions of galaxies. DESI, based in Arizona, is conducting an even more ambitious survey. It is measuring the distance to tens of millions of galaxies with exquisite precision by analyzing their light spectra. This process allows cosmologists to create a three dimensional map of the universe through time. The core data they are both collecting relates to the universe’s expansion history. By observing distant galaxies, whose light has taken billions of years to reach us, astronomers can effectively look back in time and plot how quickly space was stretching at different epochs. This history is the crucial fingerprint of the forces at play, namely the constant tug of war between gravity pulling things together and dark energy pushing them apart.
For over two decades, the standard model of cosmology has operated on the assumption that the repulsive force of dark energy is constant. This is represented by a value in the cosmological equations known as the equation of state, written as w. The standard model, which has been fantastically successful at explaining a vast range of cosmic observations, assumes that w=−1. This value corresponds to a perfect cosmological constant, an intrinsic energy of space itself that never changes. It implies that the repulsive pressure of dark energy is constant and unyielding. The new data, however, hints that this may not be the case. The combined analysis from DES and DESI suggests that w is not precisely minus one. The measurements indicate a small but statistically significant deviation, pointing to a value that is slightly greater than minus one. This implies that the repulsive pressure of dark energy is not constant but is instead weakening over cosmic time.
While the deviation is small, its appearance in two independent, powerful surveys gives the finding significant weight. It has been reported with a statistical confidence of 4.2 sigma. In the world of particle physics and cosmology, this is a very strong indication. A 5 sigma result is typically considered the gold standard for a “discovery,” but a 4.2 sigma signal means that the probability of this being a random statistical fluctuation is incredibly small, less than 1 in 100,000. It is a result that forces the scientific community to take the possibility of dynamic dark energy seriously. If this trend is real and continues, the consequences are unavoidable. A weakening repulsive force means that the cosmic acceleration must slow down. Eventually, if the repulsive pressure drops below a critical threshold, the expansion of the universe will cease altogether.
To explain this specific observational puzzle, Tye and his team developed an updated cosmological model. Their framework is elegant, introducing two key elements to the cosmic story: an extremely lightweight particle known as the axion and an underlying negative cosmological constant. The axion is not a newly invented particle. It was first proposed decades ago for entirely different reasons, to solve a vexing problem in the theory of the strong nuclear force. In this cosmological model, a field associated with this ultralight axion provided the initial impetus for cosmic acceleration. In the early universe and for much of cosmic history, the energy stored in this axion field acted just like dark energy, pushing space apart and driving the accelerated expansion we observe today. However, unlike a true cosmological constant, the energy of this field is not constant. It evolves, slowly dissipating over billions of years.
As the axion field’s energy diminishes, it unmasks the true, underlying nature of the vacuum energy, which in their model is negative. A negative cosmological constant produces a subtle, universal attractive force, a sort of background pressure that pulls space itself inward. For most of cosmic history, this negative pressure has been completely overwhelmed by the powerful repulsive force of the axion field. But as the axion’s influence wanes, this negative constant will become the dominant force governing the universe’s fate. The model’s parameters are not chosen at random. They are the values required to perfectly fit the observed data from DES and DESI. This fitting process yields a cosmological constant of approximately −1.6 and an incredibly tiny axion mass of 2.9×10−33 electronvolts. These specific numbers, derived from observation, are what define the entire timeline of the universe, from its birth to its predicted death in a “Big Crunch.”
If this model proves accurate, the transition from expansion to contraction will be a gradual and epic process. The reversal will at first be imperceptible. For billions of years after the universe reaches its maximum size, galaxies will simply stop receding. Over immense timescales, however, the change would become apparent. The light from distant galaxies, which for billions of years has been stretched to longer, redder wavelengths by the expansion of space, would begin to be compressed. The universe would become progressively blue shifted. The night sky, instead of growing darker and emptier as galaxies accelerate away, would eventually grow brighter. The cosmic microwave background, the faint afterglow of the Big Bang, would also begin to blue shift, its temperature slowly climbing from just above absolute zero.
In this contracting phase, many of the processes that have defined our universe would run in reverse. Clusters of galaxies would fall together and merge, and the renewed proximity and compression of interstellar gas could trigger a new, final burst of star formation throughout the cosmos. As the contraction accelerates, the temperature of the cosmic background radiation would climb from microwaves to infrared, and then into the visible spectrum, bathing the entire universe in a uniform, ever brightening glow. In the final epochs, the compression would become catastrophic. Superclusters would merge into one another, and the largest black holes would consume surrounding matter at a ferocious rate. The density of matter and radiation would rise to levels not seen since the first few moments after the Big Bang. Temperatures would climb to billions of degrees, hot enough to break atoms apart into their constituent protons and neutrons, and then to tear those apart into a plasma of quarks and gluons. In the final moments, the entire observable universe would exist as a single, incandescent storm of unimaginable energy and pressure, collapsing inward until space and time themselves compress into a final singularity.
This dramatic vision of a collapsing universe stands in stark contrast to the Standard Model of Cosmology, a framework known to scientists as Lambda Cold Dark Matter, or ΛCDM. For over two decades, ΛCDM has been the bedrock of our understanding of the cosmos. It has successfully described the universe as having a positive cosmological constant, denoted by the Greek letter Lambda (Λ, which is the source of a constant dark energy that causes space to expand forever at an ever accelerating rate. The success of this model cannot be overstated. It accurately predicts the structure of the cosmic microwave background, the large scale distribution of galaxies, and the observed abundance of light elements. The new model and its 4.2 sigma evidence present one of the most significant challenges yet to this long standing consensus.
Interestingly, a universe that ends in a Big Crunch is not without theoretical support. Some areas of fundamental physics, particularly string theory, suggest that universes with a positive cosmological constant, like the one we think we live in, might be inherently unstable. These theories often predict a “landscape” of possible universes, where universes with negative vacuum energy, leading to eventual collapse, are far more common and stable. The new observational data, therefore, could be providing a compelling and long awaited link between the vast scales of astronomical observation and the microscopic realm of theoretical physics. While incredibly intriguing, this is not yet a closed case. The findings represent a tantalizing hint, but not yet definitive proof. The scientific process demands further evidence and scrutiny. Fortunately, the next generation of cosmological experiments is already underway. The Vera C. Rubin Observatory and the Euclid space telescope will map the universe with even greater depth and precision, providing the crucial data needed to either confirm this startling deviation in the behavior of dark energy or to rule it out, reaffirming the standard model. For now, we are left with a profound question: is our universe destined to expand into a cold and lonely eternity, or is it already on a path toward a final, fiery reunion?
A possibility could also be thinking of it as 1 bubble in a multiverse. Eventually there is not enough matter and energy to expand endlessly so it pops or gets squeezed.
Another thought
It's also theorized that the edge of the observable universe is basically an 'event horizon' because the rate of expansion is so great that light and radiation would never be able to cross the expanse because it will always be moving away.live long and prosper as best you can Jacque
Sia, that still leaves the possibility that after the collapse, there could be another big bang. This could be another long term repeating pattern. Just a thought in my part. ChristopherBlackwell
on October 6, 2025, 4:53 pm
, which is the source of a constant dark energy that causes space to expand forever at an ever accelerating rate. The success of this model cannot be overstated. It accurately predicts the structure of the cosmic microwave background, the large scale distribution of galaxies, and the observed abundance of light elements. The new model and its 4.2 sigma evidence present one of the most significant challenges yet to this long standing consensus. 
