Given the vast scale of the universe, studying its early days is akin to looking into the past. Faint light from distant galaxies continues to traverse the cosmos to reach Earth, thus the farthest extent of the observable universe is light from the past.
However, peering into the ancient universe, formed by the Big Bang approximately 13.8 billion years ago, poses an immensely challenging task. The range of modern telescopes, capable of observing different wavelengths of light, has thus far expanded throughout the universe. Therefore, scientists have turned their attention to a phenomenon that serves as a cosmic timekeeper: a standard candle.
A standard candle, or a supermassive black hole actively accreting at the center of a newly formed galaxy, shines so brightly that it outshines our Milky Way by a factor of 100. This light acts as a cosmic clock that researchers can use to track the passage of time in the universe.
Observing standard candles over time allows the team of astronomers to understand how the universe is accelerating as it ages. The results of the study were published in the journal Nature Astronomy on July 3rd.
“When looking back to a time when the universe was just over 1 billion years old, we found that time appeared to be flowing around 5 times slower,” said Geraint Lewis, the lead researcher and a professor of astrophysics at the University of Sydney and the Sydney Institute for Astronomy.
The research indicates that the universe is expanding and accelerating at an increasing rate, a phenomenon that scientists are striving to explain. Deciphering what occurred in the early days of the universe can help scientists unravel the biggest mysteries concerning its origin, evolution, and future.
“Thanks to Einstein, we know that time and space are linked, stemming from the peculiar starting point of the Big Bang, and the universe is expanding,” Professor Lewis stated.