Quasar 'clocks' show the universe was five times slower soon after the Big Bang

One of the riddles of Einstein's expanding cosmos has been solved when scientists for the first time witnessed the early universe growing in extremely slow motion. The study has been released in Nature Astronomy.

According to Einstein's general theory of relativity, the cosmos in the past should have moved far more slowly than it does now. Looking back that far in time has been difficult, though. The enigma has finally been solved by scientists utilizing quasars as "clocks."

Lead researcher Professor Geraint Lewis from the School of Physics and Sydney Institute for Astronomy at the University of Sydney stated, "Looking back to a time when the universe was just over a billion years old, we see time appearing to flow five times slower."

One second might feel like one second if you were there, in this young cosmos, but from our vantage point more than 12 billion years in the future, that early period seems to linger.

In order to study this temporal dilation, Professor Lewis and his University of Auckland coauthor Dr. Brendon Brewer used observational data from over 200 quasars, which are hyperactive supermassive black holes in the cores of early galaxies.

We now understand, according to Einstein, that space and time are interconnected, and that the universe has been expanding ever since the Big Bang, at the beginning of time.

"Due to the expansion of space, time should appear to move considerably more slowly in the early cosmos than it does now, according to our measurements.

We have demonstrated in this study that this dates back to around a billion years after the Big Bang.

Previously, scientists used supernovae, or large exploding stars, as "standard clocks" to validate this slow-motion cosmos back to roughly half the age of the universe. Supernovae are incredibly brilliant, yet given the vast distances required to view the early cosmos, it is challenging to observe them.

This time horizon has been pushed back by observing quasars to barely a tenth of the age of the universe, proving that the cosmos appears to accelerate with age.

Supernovae behave like a single burst of light, making them simpler to examine, while quasars are more complicated, acting like a continuous fireworks display, according to Professor Lewis.

What we have done is disassemble this fireworks display, demonstrating that quasars may also serve as accepted chronometers for the early cosmos.

Astrostatistician Dr. Brewer and Professor Lewis examined the specifics of 190 quasars spotted during a two-decade period. They were able to standardize the "ticking" of each quasar by combining the data made at different colors (or wavelengths)—green light, red light, and into the infrared. They discovered the universe's expansion was imprinted on each quasar's ticking by using Bayesian analysis.

Professor Lewis remarked, "With this fine data, we were able to record the tick of the quasar clocks, indicating the impact of expanding space.

These findings support Einstein's theory of an expanding universe even more, in contrast to prior research that was unable to detect the time dilation of far-off quasars.

The validity of the notion that space is expanding was also questioned as a result of these previous research, according to Professor Lewis.

"With these new data and analysis, however, we've been able to find the elusive tick of the quasars and they behave just as Einstein's relativity predicts," the scientist added.