Physicists Say a 26.7-Billion-Year-Old Universe Could Work Without Dark Matter or Dark Energy
University of Ottawa researchers tested a 'tired light' model with changing physical constants against galaxy rotation, cosmic expansion and early-element formation.
A provocative cosmological model suggests the universe could be 26.7 billion years old, almost twice the accepted age, and might not need dark matter or dark energy to explain its behavior. Researchers at the University of Ottawa tested the theory against several major astronomical observations and report that it can account for galaxy rotation, cosmic expansion and the formation of the early elements.
Throughout 2025 and 2026, Rajendra Gupta, an adjunct professor in the university's Department of Physics, and postdoctoral researcher Dr. Nikolaos Samaras evaluated a framework called CCC+TL, short for "covarying coupling constants plus tired light." Rather than invoking dark matter and dark energy, the model proposes that some effects attributed to them could come from changes over time in fundamental physical constants, the numbers that govern how particles and forces interact.
The standard picture, known as ΛCDM, includes both ingredients. Dark matter is thought to supply extra gravity that helps explain how galaxies move and how large structures hold together. Dark energy is the name for whatever is driving the accelerating expansion of the universe. Extensive observations support their gravitational and cosmological effects, but neither has been directly identified despite decades of searching.
The standard model also faces a puzzle. Telescopes have found surprisingly large and mature galaxies at a time when the conventional timeline says they should barely have begun forming. A universe nearly twice as old would give those galaxies more time to grow. If further research supports the findings, the authors say, the theory could offer a very different account of cosmic evolution.
Testing such a model takes more than adjusting the standard one. CCC+TL modifies the Einstein and Friedmann equations, which describe gravity and the expansion of the universe, so Gupta and Samaras had to develop equations and computer programs adapted to the model for each test. The latest paper, published in the journal Universe in 2026, is a Big Bang nucleosynthesis consistency test, checking whether the model reproduces the light elements formed in the first minutes of the universe.
"Most emerging models explain only a limited set of observations," Gupta said. "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." That last test is the one that matters most to other cosmologists. The cosmic microwave background, the afterglow of the early universe, is the dataset on which dark matter has the strongest claim, and the Ottawa results on it have not yet been published.
The proposal remains a minority view, and it will need to survive scrutiny from the wider community before it displaces the standard model. For now it offers a testable alternative: a universe with no dark sector, older than assumed, and governed by constants that drift over cosmic time.
