Time appears to run five times slower when the universe was about 1 billion years old, scientists said Monday. The researchers said things were moving in slow motion compared to today. They conducted this study using observations of a fierce class of black holes called quasars.
A study published in the journal Nature Astronomy identified cosmic time dilation in a sample of 190 quasars monitored over more than two decades in multiple wavelength bands. The new findings support Albert Einstein’s theory of relativity, according to which the distant universe moved much more slowly.
Scientists have previously used observations of very bright exploding stars called supernovae as cosmic clocks to show that time ran twice as slowly back when the universe was half its current age.
Just over a billion years after the Big Bang, time seemed to slow down five times, the study said. Geraint Lewis, an astrophysicist at the University of Sydney and lead author of the new study said: “While from here ‘everything looks like it’s in slow motion’, Lewis stressed that the experience of time in these distant places is no different.”
“If I could magically take you back 10 billion years and throw you next to one of these quasars and you had a stopwatch, time would just be normal,” he told AFP. “One second would be one second.
To measure this phenomenon, called cosmological time dilation, Mr Lewis and statistician Brendon Brewer from the University of Auckland analyzed data from 190 quasars collected over two decades. Quasars, supermassive black holes at the centers of distant galaxies, are considered the brightest and most powerful objects in the universe.
That makes them “useful beacons for mapping the universe,” Mr. Lewis said. However, they have proved more difficult to turn into cosmic clocks than supernovae, which provide a reliable single flash like a “tick”.
Previous attempts to use quasars to measure time dilation have failed, leading to some “strange proposals”, Mr Lewis said.
These included theories that perhaps quasars aren’t as far away as thought or even that “something fundamental has been broken in cosmology,” he said.
But the new research “puts everything back into place,” Mr. Lewis said. It also confirmed that “Einstein is right again,” he added.
The researchers were able to succeed where other attempts had failed because they had so much more data about quasars, Lewis said. Recent advances in the statistical understanding of randomness have also helped.
To turn quasars into clocks with measurable ticks, scientists needed to understand the turbulent explosions that occurred as black holes swallowed material.
Mr Lewis likened it to watching fireworks, in which the big flashes appear to be random, but the different elements “grow brighter and dimmer in their own timelines”.
“What we’ve done is decipher these fireworks, which show that even quasars can be used as standard time markers for the early universe.”
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