Time flows more slowly in the ancient universe: quasars “clocks” confirm Einstein’s theory
Observations of nearly 200 quasars have shown that time in the early universe ran five times slower than it does today.
In the new research scientists used quasars as cosmic clocks to watch the early universe move at an extremely slow pace, further confirming Einstein’s theory of general relativity.
By studying data from nearly 200 quasars, hyperactive supermassive black holes at the centers of early galaxies, the team found that time seemed to run five times slower when the universe was just over a billion years old.
Observational data from almost 200 quasars shows that Einstein is right – again – about the cosmos time slowing down. Scientists have observed the early universe moving at an extremely slow pace for the first time, revealing one of the mysteries of Einstein’s expanding universe. Einstein’s general theory of relativity means that we should observe the distant – and therefore ancient – universe moving much slower than the present day. However, it was not easy to look so far into the past. Scientists have managed to unravel this mystery by using quasars as clocks.
“Looking back at a time when the universe was just over a billion years old, we see that time seems to flow five times slower,” said study lead author Professor Geraint Lewis of the University of Sydney School of Physics and Sydney Institute of Astronomy.
“If you were there in this infant universe, one second would seem like one second – but from our position, more than 12 billion years into the future, this early time seems to drag on.”
Professor Lewis and collaborator Dr. Brandon Brewer of the University of Auckland used observational data from nearly 200 quasars – hyperactive supermassive black holes at the centers of early galaxies – to analyze this time dilation.
“Thanks to Einstein, we know that time and space are intertwined, and since the beginning of time at the Big Bang singularity, the universe has been expanding,” said Professor Lewis.
“Such an expansion of space means that our observations of the early universe must appear much slower than time flows today.
“In this article, we have established that this is true until about a billion years after the Big Bang.”
Previously, astronomers had confirmed this slowed-down universe to about half the age of the universe, using supernovae – massive exploding stars – as the “standard clock”. But although supernovae are extremely bright, they are difficult to observe at the vast distances needed to peer into the early universe.
By observing quasars, this time limit has been pushed back to a tenth of the age of the universe, confirming that the universe appears to be accelerating as it ages.
“Detecting Cosmological Time Dilation of High Redshift Quasars”, Geraint F. Lewis and Brandon J. Brewer, July 3, 2023, Nature Astronomy.