Time appears to flow five times slower in the early Universe, according to a scientific study using exceptionally bright cosmic objects, quasars, for the first time to confirm this strange phenomenon.
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Albert Einstein’s theory of relativity predicts that as the universe expands, we “should watch the distant universe grow in slow motion,” Geraint Lewis, an astrophysicist at the University of Sydney and lead author of the published study, tells AFP Monday in Nature Astronomy.
Researchers had used observations of stars ending their lives in explosions, called supernovae, to show that when the universe was half its current age, 13.8 billion years, time seemed to pass twice as slowly.
The new study uses quasars, which are incomparably brighter, and stretches back as far as a billion years after the birth of the universe. According to the study, time seems to flow five times slower there.
“Everything seems to be in slow motion,” Prof. Lewis says for the current observer, but “if I could magically transport you ten billion years ago to get you close to one of these quasars and watch your stopwatch, everything would feel normal,” he explained.
“A second would be a second,” he added.
To measure the phenomenon, dubbed cosmological time dilation, Professor Lewis and New Zealand University of Auckland statistician Brendon Brewer analyzed data from 190 quasars collected over a 20-year period.
Quasars, galactic cores with a supermassive black hole at their center, are considered the brightest and most energetic objects in the cosmos. This makes them, according to Professor Lewis, “very useful beacons for mapping the universe”.
The difficulty was turning them into cosmic clocks that are as easy to operate as supernovae. The latter provide a single signal, but reliable over time.
In quasars, the researchers achieved their goal thanks to a large amount of data and recent advances in the statistical understanding of random events.
In this case, researchers were able to interpret the multiple collisions that occur as the quasar’s black hole absorbs matter.
Professor Lewis likened it to fireworks, where the large sprays appear to explode at random, but the elements ‘light up and then fade’ in a defined and regular time frame.
“We reduced these fireworks and showed that quasars can also be used as time beacons for the early days of the universe,” he said. And thus prove that “Einstein is right once again”.