A fundamental consequence of the relativistic picture of expanding space is cosmological time dilation, where events in the distant Universe appear to run slowly compared to those in the local cosmos. Whilst this time dilation has been unambiguously detected in extremely distant supernovae, the appearance of time dilation in other distant sources is less conclusive. In new research, a duo of astrophysicists from the University of Sydney and the University of Auckland identified the cosmic time dilation in a sample of 190 quasars located in the early Universe.
Albert Einstein’s general theory of relativity means that we should observe the early Universe running much slower than the present day.
However, peering back that far in time has proven elusive. Astrophysicists have now cracked that mystery by using quasars as ‘clocks.’
“Looking back to a time when the Universe was just over a billion years old, we see time appearing to flow five times slower,” said University of Sydney’s Professor Geraint Lewis.
“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, that early time appears to drag.”
To analyze this time dilation, Professor Lewis and his colleague, University of Auckland’s Dr. Brendon Brewer, used data from a sample of 190 quasars observed over two decades.
Combining the observations taken at different colors (or wavelengths), they were able to standardize the ‘ticking’ of each quasar.
Through the application of Bayesian analysis, they found the expansion of the Universe imprinted on each quasar’s ticking.
“Thanks to Einstein, we know that time and space are intertwined and, since the dawn of time in the singularity of the Big Bang, the Universe has been expanding,” Professor Lewis said.
“This expansion of space means that our observations of the early Universe should appear to be much slower than time flows today.”
“In…
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