The universe might have an expiration date. Henry Tye, the Horace White Professor of Physics Emeritus at Cornell, published a paper in the Journal of Cosmology and Astroparticle Physics on February 15th, 2026, calculating that the universe will keep expanding for about 11 billion more years, reach its maximum size, and then start shrinking — collapsing back into a single point roughly 20 billion years from now. Given that the universe is currently 13.8 billion years old with an estimated total lifespan of 33 billion years, we’re essentially at cosmic halftime.
For the last quarter century, the scientific consensus held that dark energy — the mysterious force making up 68% of the universe’s total energy budget — would push space apart forever, leading to a cold, dark Heat Death trillions of years from now. But stunning new data from two massive observatory projects — the Dark Energy Spectroscopic Instrument (DESI) in Arizona and the Dark Energy Survey in Chile — suggests dark energy might be changing over time. If it’s weakening rather than staying constant, the entire standard model of cosmology needs revision.
Tye isn’t alone in this conclusion. Professor Young Wook Lee at Yonsei University in Seoul independently arrived at similar findings using supernova data, adjusting for the ages of host galaxies. Two teams on opposite sides of the planet, using different methods and different data sets, pointing in the same direction. Cambridge cosmologist George Efstathiou has pushed back, calling some of the analysis “dangerous,” but the convergence of independent evidence is hard to dismiss.
The implications are profound. If the cosmological constant is truly negative, the universe doesn’t end in the quiet whimper of Heat Death or the violent shredding of a Big Rip — it ends in a Big Crunch, everything collapsing back to a singularity like the Big Bang played in reverse. Some physicists speculate this could trigger another Big Bang, creating a cyclical universe that breathes in and out forever. Within the next few years, as DESI, the Euclid space telescope, and the Vera C. Rubin Observatory deliver more data, we should know which ending our universe is headed for.