July 2023

2023-07-04 02:44:44

Time appears to have run five times slower in the early universe, scientists said Monday, using extraordinarily bright cosmic objects called quasars as “clocks” for the first time to confirm this strange phenomenon.

The Einstein’s theory of relativity predicts that because space is expanding, “we should see the distant universe running in slow motion,” said Geraint Lewis, an astrophysicist at the University of Sydney and lead author of a new study. The researchers had previously used observations of very bright exploding stars called supernovae as cosmic clocks to show that time ran twice as slow when the universe was half its current age. The new study used even brighter quasars to look further back into the universe’s 13.8 billion-year history.

Just over a billion years following the Big Bang, time seemed to flow five times slower, according to the study published in the journal Nature Astronomy. While “everything seems to slow down” from here, Lewis stressed that the experience of time in these distant places was no different. “If I might magically transport you back 10 billion years and drop you next to one of these quasars, and you have a stopwatch, time would be normal,” he told AFP.

“A second would be a second.”

In order to measure this phenomenon, which is called cosmological time dilation, Lewis and University of Auckland statistician Brendon Brewer analyzed data from 190 quasars collected over two decades.

Quasars are believed to supermassive black holes at the center of distant galaxies, they are the brightest and most powerful objects in the universe. This makes them “useful beacons for mapping out the universe,” Lewis said.

But they have proven more difficult to convert into cosmic clocks than supernovae, which provide a single reliable flash as a “tick.” Previous attempts to use quasars to measure time dilation had failed, leading to some “weird suggestions,” Lewis said.

These included theories that perhaps quasars were not as distant as thought, or even that “something fundamental was broken” in cosmology, he said.

“Einstein was right”

But the new research “puts everything back in the right place,” Lewis said. He also confirmed that “Einstein is right once more,” she added. The researchers were able to succeed where other attempts had fallen short because they had much more data on quasars, according to Lewis. Recent advances in the statistical understanding of randomness have also helped.

For turn quasars into clocks With measurable ticks, the researchers had to make sense of the turbulent explosions that occurred when black holes swallowed material.

Lewis compared it to watching a fireworks display, in which the big flashes seem random but the different elements “light up and fade out on their own kind of time scales.” “What we have done is unravel this fireworks display, showing that quasars can also be used as standard markers of time for the early universe.”

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