Dark-energy evidence suggests the universe will end in a “big crunch” roughly 20 billion years from now.
The universe is nearing the halfway point of what may be a 33-billion-year lifespan, according to new calculations by a Cornell physicist using updated dark energy data. The findings suggest that the cosmos will continue expanding for roughly another 11 billion years before reversing course, contracting back into a single point in a dramatic “big crunch.”
Henry Tye, the Horace White Professor of Physics Emeritus in the College of Arts and Sciences, arrived at this conclusion after updating a theoretical model that incorporates the “cosmological constant,” a concept first proposed by Albert Einstein more than a century ago and widely used by modern cosmologists to describe the universe’s expansion.
“For the last 20 years, people believed that the cosmological constant is positive, and the universe will expand forever,” Tye said. “The new data seem to indicate that the cosmological constant is negative, and that the universe will end in a big crunch.”
Tye is the corresponding author of a recent study about the findings published in the Journal of Cosmology and Astroparticle Physics.
Predicting the universe’s fate
The universe, now about 13.8 billion years old, continues to expand outward. According to Tye, the future depends on the value of the cosmological constant: if it is positive, expansion will continue indefinitely; if it is negative, the universe will eventually reach a maximum size before reversing direction and collapsing entirely. His calculations support the latter scenario—a future in which the cosmos contracts to zero, marking the ultimate end of space and time.
The latter is the conclusion Tye reached with his recent calculation.
“This big crunch defines the end of the universe,” Tye wrote. He determined from the model that the big crunch will happen about 20 billion years from now.
New data from dark energy observatories
The big news this year is the reports by the Dark Energy Survey (DES) in Chile and the Dark Energy Spectroscopic Instrument (DESI) in Arizona this spring. Tye said these two observatories, one in the southern hemisphere and one in the northern, are in good accord with each other. The whole idea of the dark energy survey of these two groups is to see whether dark energy – 68% of the mass and energy in the universe – really comes from a pure cosmological constant. They found that the universe is not just dominated by a cosmological constant, dark energy. The dark energy actually has something else going on.
Tye and his collaborators proposed in the paper a hypothetical particle of very low mass that behaved like a cosmological constant early in the life of the universe, but does not anymore. This simple model fits the data well but tips the underlying cosmological constant into negative territory.
“People have said before that if the cosmological constant is negative, then the universe will collapse eventually. That’s not new,” Tye said. “However, here the model tells you when the universe collapses and how it collapses.”
Observations and the future of cosmology
There are more observations to come, Tye said. Hundreds of scientists are measuring dark energy by observing millions of galaxies and the distance between galaxies, gathering even more accurate data to feed into the model. DESI will continue observations for another year, and observations are ongoing or will begin soon at several others, including the Zwicky Transient Facility in San Diego; the European Euclid space telescope; NASA’s recently launched SPHEREx mission; and the Vera C. Rubin Observatory (named after Vera Rubin, M.S. ’51).
Tye finds it encouraging that the lifespan of the universe can be quantitatively determined. Knowing both the beginning and the end of the universe provides a greater understanding of the universe, the goal of cosmology.
“For any life, you want to know how life begins and how life ends – the end points,” he said. “For our universe, it’s also interesting to know, does it have a beginning? In the 1960s, we learned that it has a beginning. Then the next question is, ‘Does it have an end?’ For many years, many people thought it would just go on forever. It’s good to know that, if the data holds up, the universe will have an end.”
Reference: “The lifespan of our universe” by Hoang Nhan Luu, Yu-Cheng Qiu and S.-H. Henry Tye, 18 September 2025, Journal of Cosmology and Astroparticle Physics.
DOI: 10.1088/1475-7516/2025/09/055
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48 Comments
“The lifespan of our universe according to our speculative Axion Dark Energy model, with an ultralight axion plus a negative cosmological constant.”
Blake’s 7 always said the answer to the universe was 42,is this the positive light energy ‘In’ the universe,if so does this ominously mean were all doomed in 20 billion years with the negative 68%???
42 was the answer to the ultimate question of life, the universe, and everything in Douglas Adams’ “Hitchhiker’s Guide To The Galaxy” not Blake’s 7.
Warn all you want to, Physicists.
If I’m going to die in a crunch, I’m thinking a Sikh driving an 18-wheeler is a much better bet.
Especially with a California CDL.
Too true.
That reads racist.
Pay more attention to the news before you play the race card.
I can save everyone! I know the exit point to the multiverse.
I just want to know the names of the illuminati CIA agents who planted the explosives in the twin towers 😲✝️God bless you and me
Put down the crack pipe.
I thought the consensus was that the expansion was accelerating as the universe increases in size. There seems to be competing theories to acquire grants that will prove nothing but provide PhD’s job income and speaking engagements.
Be grateful that the unemployable can find mentally stimulating work.
Science has proven its worth over and over again. And speaking engagement side income depends on a listening public, not on the science as such.
Glad you’re back.
The entire time I was growing up, during the 70s and 80s, the Big Crunch was the predominant theory. Then along came dark matter and dark energy during the 90s, and all of a sudden it was the Big Rip. Now we’re back to the Big Crunch again? 🤷♂️
Physicists Warns… ? Thanks for the warning. Need to get my things straight beforehand.
Nice click bait title. I’ll be sure to report it as misleading or sensational on my feed, because even though *I* knew before coming here that it was nonsensical, there are many people who would click through our of ignorant, reactive fear. This type of garbage writing is how we wind up with anti-science fools in government spouting misinformation without being laughed out of office.
No one has any idea what you’re crying about.
But we all suspect you do it constantly…
Amen.
A, the “amen” was meant to follow Keyrlis.
There is nothing wrong with either the write up or the business model of click bait titles.
It’s amazing how these scientists always assume one circumstance equals the end of the story. Much like the Big Bang WASN’T the beginning, the Big Crunch isn’t necessarily the end. All that can be shown in these calculations is a return to singularity.
No. All they can do is to make a poorly tested proposal for how dark energy behaves. The rest is even more speculative.
Better start selling those crunch credits to offset the effects of the crunch.
Friedrick Nietzsche was correct! The universe expands from a big bang until it reverses and collapses in on itself and results in another big bang. Time after time after time…over and over, time without number. That our lives will repeat exactly the same over and over, throughout eternity. Blessed is one whose life is so grand that they cheer on the prospect of eternal repetition.
Wrong! But this platform won’t allow me to elaborate (tried it before… it got removed).
The world will end when the Creator says. Physicists arent omniscient. All is theory, not reality.
Our Creator will have the last word.
Physicists aren’t omniscient, but at least they killed of your proposed magic. The entirely natural space expansion process has since 2016ish robustly and beyond reasonable doubt been shown to produce the universe. The magic show is over.
Physicists aren’t omniscient, but they own this area now. The entirely natural space expansion process has since 2016ish robustly and beyond reasonable doubt been shown to produce the universe. Your proposal is wrong.
Well, if that gives me the chance to regain my lost youth and his girlfriends of the day………..
The absence of high entropy at the start implies that no such recurrence has happened.
If matter and energy can neither be created nor destroyed, then how could there possibly be an end to the universe? The matter and energy must go somewhere after this supposed big crunch and that would still be the universe. It can’t just all disappear into nothingness.
It will explode again in an eternal recurrence.
For thousands years, Hindu cosmology has stated that universe goes through endless cycles of creation, sustenance and destruction. Ultimately, there is no beginning and end of these cycles.
And then it starts all over again
The Universe is infinite. That means it doesn’t “end” just as it didn’t “begin.” The Universe as we know it (probably) began with the big bang, but there needed to be “something” that went bang in the first place. Picture the Universe as an infinite loop. There’s a single point in the center where all the lines converge. That point is the point of transformation not the end or beginning of the loop. Just the point where it begins to mirror the other side
An expanding universe isn’t stationary, so has in general no useful total energy definition. That line of analysis isn’t relevant.
For thousands years, Hindu cosmology has stated that universe goes through endless cycles of creation, sustenance and destruction. Ultimately, there is no beginning and end of these cycles.
And then it starts all over again
Welp, time to buy more life insurance.
Don’t think I’m go to worry too much about this one.
I think there are lots of problems with this theory. If all the universe mass is scattered outward why does it come back in. The theory is based on mass slowly accumulating in one spot becoming so strong is sucks everything back in.
I just find that a bit unlikely but maybe? Right now our universe is expending maybe in 10 billion years they will be able to prove it stopped expanding and it is starting to reverse and shrink.
Obviously none of us will be around and most likely will be extinct. Who knows maybe we will find our way into space and find other places to live before our sun burns the earth to a crisp in 400 million years. Once can hope. There is also the theory of time travel and going back in time. One never knows what we might figure out in the next 20k years.
This work is intriguing but the big Question is , will humanity last . Priorities should lead us , each day we spend money in tremendous amounts those monies could be used to answer basic questions of space travel first or even how our planet will support our needs should leverage a higher calling of thought than pinpointing the age of the universes or how it will end . Waste of intellect that only tries to solves a personal question . instead of this world or even this galaxy think Humanity first we will solve as we grow if we grow . Answer the immediate problems because there is no future if we fail .
Science – a very useful tool with some of the highest returns on investment – is mutually reinforcing, hence this work is no waste of intellect.
The models add 2 (!) parameters, which makes for a better fit than the simpler concordance model. But they don’t do a model vs degree of freedom comparison, so we don’t know which model is better.
DESI data release 2 is problematic to use for extracting tensions with concordance cosmology – the Hubble rate fluctuations have moved and it has by itself less tension with concordance cosmology – so I wouldn’t expect that papers based on it will go very far. Better wait for better data, and stop with the p-hacking for digging up ‘notable deviations’ (as there will always be some if you do that).
The DESI data revealed that ‘Dark Energy’ is a variable, not a constant. So, now we get more placeholders to the Standard Model in order the square the math with observations.
Early in 2023, I sent a hypothesis in to NASAsolve that offered an alternative to the Standard Model, and it predicted the results of the DESI observations. I put an abridged version on this site after the DESI results were released, but my post got pulled.
My hypothesis may not be correct, but there is observational evidence to support it, and the physics are much simpler, i.e. no placeholders. We will see.
Once again, glad you’re back.