Experts Utilize Quasars as “Clocks” to Measure Cosmic Time Dilation, Confirming Einstein’s Theories.
Scientists have reported that time in the early universe appears to have flowed five times slower than it does today, according to an AFP report on July 3. This is the first time they have used quasars as “clocks” to confirm this unusual phenomenon.
Illustration of a quasar, considered the brightest object in the universe. (Photo: NOIRLab/NSF/AURA/J. Da Silva)
Einstein’s theory of relativity predicts that, as the universe expands, humans will perceive distant cosmic objects moving more slowly, according to Geraint Lewis, an astrophysicist at the University of Sydney and the lead author of the new study published in the journal Nature Astronomy.
The universe is estimated to be about 13.8 billion years old. Previous researchers had used observations of supernovae—brilliant star explosions—as “cosmic clocks” to demonstrate that time flowed twice as slowly when the universe was half its current age.
The new research utilized quasars, which are even brighter than supernovae, to delve deeper into the history of the universe. It found that over a billion years after the Big Bang—the explosion that birthed the universe—time appeared to flow only one-fifth as fast as it does now. This phenomenon is known as cosmic time dilation.
To measure cosmic time dilation, Lewis and statistician Brendon Brewer from the University of Auckland analyzed data from 190 quasars collected over two decades. Quasars form when a supermassive black hole at the center of a distant galaxy “consumes” surrounding material and emits intense radiation. They are considered the brightest and most powerful objects in the universe, making them useful “beacons” for charting the cosmos, according to Lewis.
However, turning quasars into “cosmic clocks” is far more challenging than using supernovae. Lewis noted that many previous attempts to use quasars to measure cosmic time dilation had failed, leading to some strange conclusions. The new study helps to correct these discrepancies and confirms that Einstein was indeed correct.
According to Lewis, the success of their study is attributed to having more data on quasars. Recent advancements in statistical knowledge regarding randomness were also beneficial.
To convert quasars into clocks with measurable time, the research team had to understand the chaotic explosions that occur when black holes consume material. Lewis likened these explosions to a fireworks display, where the flashes of light may seem random, but different factors illuminate and fade over their own timescales. “We have clarified this fireworks display, showing that quasars can also be used as standard time markers for the early universe,” Lewis stated.
