Our universe could be twice as old as current estimates, according to a model proposed by a new study from the University of Ottawa, Canada.
“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,” said study author Rajendra Gupta, adjunct professor of physics in the Faculty of Science at the university.
The research team said that their model challenges the dominant cosmological models of calculating our universe’s age, which largely involve measuring the time elapsed since the Big Bang and studying the oldest stars based on the redshift of light coming from distant galaxies.
Redshift refers to an observed elongating of wavelength of light from distant galaxies, generally interpreted as evidence of the universe expanding.
In 2021, the current or standard cosmological model, called the Lambda-CDM concordance model, estimated the age of our universe to be 13.797 billion years old.
The Lambda-CDM model assumes that the universe was created in the “Big Bang” from pure energy, and is now composed of about 5 per cent ordinary matter, 27 per cent dark matter, and 68 per cent dark energy.
However, the discovery of evidence of ‘early’ galaxies in advanced stages of cosmological evolution by NASA’s James Webb Space Telescope and the existence of stars like the Methuselah, one of the oldest stars known, has puzzled many scientists.
These ‘early’ galaxies, whilst surprisingly small in size and said to exist a mere 300 million years or so after the Big Bang, have been observed to possess a level of maturity and mass typically associated with billions of years of cosmic evolution, which the researchers of this study say is insufficiently explained by the standard model.
Tired light theory, proposed by the Swiss astronomer Fritz Zwicky in 1929, is a class of hypothetical redshift mechanisms proposed as an alternative explanation for the observed redshift of light from distant galaxies.
Zwicky suggested that the redshift came from photons losing their energy by means of interacting with matter or other photons as they travel vast distances through a ‘static’ universe. However, his theory too was found to conflict with observations.
Gupta, through this study published in the journal Monthly Notices of the Royal Astronomical Society, found that “by allowing this theory to coexist with (that of) the expanding universe, it becomes possible to reinterpret the redshift as a hybrid phenomenon, rather than purely due to expansion.”
Along these lines, Gupta suggested the idea of evolving “coupling constants”, an idea originally hypothesised by Paul Dirac, the British theoretical physicist.
Coupling constants are fundamental physical constants that influence material interactions between subatomic particles.
According to Dirac, these constants might have varied over time and thus, allowing them to evolve extends the timeframe for the formation of early galaxies observed by the Webb telescope from a few hundred million years to several billion years.
This provides a more feasible explanation for the advanced level of development and mass observed in these ancient galaxies, the study said.
Further, Gupta suggested that the traditional interpretation of the “cosmological constant”, which represents the dark energy responsible for the accelerating expansion of the universe, needed revision.
He said that this modification in the cosmological model helps address the puzzle of small galaxy sizes observed in the early universe, allowing for more accurate observations.