Universe is 13.77 billion years old, scientists claim

From a mountain high in Chile’s Atacama Desert, astronomers with the National Science Foundation’s Atacama Cosmology Telescope (ACT) have taken a fresh look at the oldest light in the universe.

Their new observations plus a bit of cosmic geometry suggest that the universe is 13.77 billion years old, give or take 40 million years.

The new estimate matches the one provided by the standard model of the universe and measurements of the same light made by the Planck satellite. This adds a fresh twist to an on-going debate in the astrophysics community, said Simone Aiola, first author of one of two new papers on the findings posted to arXiv.org.

In 2019, a research team measuring the movements of galaxies calculated that the universe is hundreds of millions of years younger than the Planck team predicted. That discrepancy suggested that a new model for the universe might be needed and sparked concerns that one of the sets of measurements might be incorrect.

“Now we’ve come up with an answer where Planck and ACT agree. It speaks to the fact that these difficult measurements are reliable," said Aiola, a researcher at the Flatiron Institute’s Center for Computational Astrophysics in New York City.

The age of the universe also reveals how fast the cosmos is expanding, a number quantified by the Hubble constant. The ACT measurements suggest a Hubble constant of 67.6 kilometres per second per megaparsec. That means an object 1 megaparsec (around 3.26 million light-years) from Earth is moving away from us at 67.6 kilometres per second due to the expansion of the universe.

This result agrees almost exactly with the previous estimate of 67.4 kilometres per second per megaparsec by the Planck satellite team, but it's slower than the 74 kilometres per second per megaparsec inferred from the measurements of galaxies.

“I didn’t have a particular preference for any specific value – It was going to be interesting one way or another,” said Steve Choi of Cornell University, first author of the other paper posted to arXiv.org.

“We find an expansion rate that is right on the estimate by the Planck satellite team. This gives us more confidence in measurements of the universe’s oldest light,” added Choi.