Universe twice as old? Ottawa researchers keep testing a 26.7-billion-year model

The universe may be 26.7 billion years old — nearly twice the figure printed in every textbook — and it may need neither dark matter nor dark energy to work. That is the claim at the center of an alternative cosmological model developed at the University of Ottawa, and its authors have spent 2025 and 2026 running it through a gauntlet of real astronomical data to see whether it survives.

The model, called CCC+TL — short for 'covarying coupling constants plus tired light' — was first proposed in a paper published July 7, 2023, in the Monthly Notices of the Royal Astronomical Society by Rajendra Gupta, an adjunct professor in the University of Ottawa's Department of Physics. In a follow-up paper published in the journal Universe, Gupta and postdoctoral researcher Nikolaos Samaras reported that the model can reproduce the observed abundances of light elements forged in the minutes after the Big Bang — one of the most demanding tests any cosmological theory must pass.

Our newly-devised model stretches the galaxy formation time by a several billion years, making the universe 26.7 billion years old, and not 13.7 as previously estimated.— Rajendra Gupta, Adjunct Professor of Physics, University of Ottawa

The immediate motivation for the theory is a puzzle that the James Webb Space Telescope has made impossible to ignore. JWST has revealed galaxies that existed only about 300 million years after the Big Bang yet already look massive and mature — a level of development that, under the standard model, should have taken billions of years to reach. CCC+TL offers a simple answer: give the early universe far more time. At the same observed redshift where the standard model places the universe at roughly 300 million years old, CCC+TL would place it at a much greater age, according to the University of Ottawa.

The standard framework that CCC+TL is challenging is called ΛCDM — Lambda Cold Dark Matter. Accepted since the late 1990s, it holds that the universe is about 13.8 billion years old, that roughly 27 percent of its energy content is dark matter (inferred from how galaxies move and how large structures hold together), and that roughly 68 percent is dark energy (the name given to whatever is accelerating the universe's expansion). Neither component has ever been directly detected.

CCC+TL replaces those two mysterious ingredients with two century-old ideas that have never quite gone away. The first is 'tired light,' proposed around 1930: rather than the universe expanding and stretching light to redder wavelengths, photons simply lose energy as they travel vast distances. The second is the idea, associated with physicist Paul Dirac, that the fundamental constants governing how particles and forces interact — the coupling constants — may not be fixed but have changed over cosmic time. Gupta allows these two effects to coexist with an expanding universe, treating the observed redshift of distant galaxies as a hybrid of all three causes rather than expansion alone.

Because the model modifies the Einstein and Friedmann equations that describe gravity and cosmic expansion, Gupta and Samaras had to build new equations and computer programs for each test rather than simply adjusting existing tools. According to Science Daily, the tests they have now reported cover: the abundances of light elements (hydrogen and helium) produced in the first minutes after the Big Bang; cosmic chronometer measurements, which reconstruct expansion history by comparing galaxy ages at different distances; the rotation curves of all 175 galaxies in the SPARC database; time dilation in supernova observations (that paper remains under review); and an initial analysis of the Bullet Cluster, the colliding galaxy system long considered one of the strongest pieces of evidence for dark matter.

The Bullet Cluster result is the most tentative. In that system, X-ray observations show that most ordinary matter sits in hot gas between the colliding clusters, yet the gravitational pull is concentrated around the galaxies themselves — behavior the standard model explains by invoking dark matter that passed through the collision with the galaxies. Under CCC+TL, the researchers say the additional gravitational effect their model predicts also follows the galaxies rather than the gas, without requiring dark matter. They describe this as only an initial proof of concept requiring much more detailed work, according to Science Daily.

Most emerging models explain only a limited set of observations. A new model must not conflict with the pillars of cosmology and astrophysics, and our findings meet that challenge, including the yet-to-be-published Cosmic Microwave Background challenge.— Rajendra Gupta, Adjunct Professor of Physics, University of Ottawa

That last phrase — the CMB challenge — points directly to the model's biggest unresolved test. The cosmic microwave background is the faint glow of radiation left over from the early universe, and its detailed pattern of tiny temperature fluctuations is one of the most precisely measured datasets in all of science. ΛCDM explains those fluctuations in exquisite detail. CCC+TL has not yet published a full comparison against that data, according to Knowridge.

Mainstream cosmologists are skeptical, and their objections go beyond the missing CMB comparison. Writing in Astronomy, cosmologist Paul Sutter laid out several specific problems. First, the model's complexity: by adding both tired light and varying constants on top of an expanding universe, it gains enough free parameters to fit many observations — but that flexibility is a weakness as much as a strength. Second, the early galaxies JWST found are not just large; they also appear young and bright, looking like galaxies only a few hundred million years old despite their size. A model that gives the universe more time does not automatically explain why those galaxies still look young. Third, if the universe were 26.7 billion years old, stars 15 to 20 billion years old should be common. They are not observed. Fourth, the tired light and varying-constants mechanisms lack explained physical processes — how exactly does light lose energy, and what drives the constants to change?

Gupta's model is interesting as a thought experiment to explore what physics we might need to explain these and perhaps future JWST observations. But as a fully functioning cosmological model, it falls far short, and creates more mysteries than it solves.— Paul Sutter, Cosmologist

Gupta has acknowledged the challenge of building a model that satisfies all of cosmology's interlocking constraints simultaneously, and frames the ongoing work as exactly that effort. A separate paper by Gupta exploring the origin of dark matter and dark energy within the CCC+TL framework is also in progress, according to Science Daily. For now, the model remains a minority position — one that has cleared several real observational hurdles but has not yet faced the full test suite that would be required to challenge ΛCDM seriously.

Why it matters — If even partially validated, CCC+TL would require rewriting the age of the universe and the role of dark matter and dark energy — but the model still faces major unresolved tests before it can seriously challenge the standard picture.

Sources differ on Whether CCC+TL's explanation of early large galaxies is complete: The model gives early galaxies billions more years to form, resolving the 'impossible early galaxy problem.' (uottawa.ca) vs JWST galaxies appear large but also young and bright — an older universe does not explain why they still look young, and no 15–20 billion-year-old stars have been found. (astronomy.com)

Sources differ on Whether the model's complexity is a strength or a weakness: The model successfully matches multiple independent observational pillars simultaneously. (sciencedaily.com) vs Adding tired light and varying constants to an expanding universe creates so many free parameters that fitting selected observations is not surprising; it also introduces unexplained new physics. (astronomy.com)

Reported by sciencedaily.com, astronomy.com, uottawa.ca, knowridge.com