In a study released this month, researchers once again made the case for “time dilation” in the early universe by using observations of a terrifying class of black holes known as quasars to show how time moved there only slightly faster than it does now. The observations of ‘ time dilation ‘ stretch back to about 12.3 billion years ago, when the universe was roughly a tenth its present age.
The study used quasars, which are among the brightest objects in the universe, as a “clock” to measure time in the distant past. Quasars are tremendously active supermassive black holes millions to billions of times more massive than our sun, usually residing at centers of galaxies. They devour matter drawn to them by their immense gravitational pull and unleash torrents of radiation including jets of high-energy particles, while a glowing disk of matter spins around them.
The researchers used observations involving the brightness of 190 quasars across the universe dating to about 1.5 billion years after the Big Bang event that gave rise to the cosmos. They compared the brightness of these quasars at various wavelengths to that of quasars existing today, finding that certain fluctuations that occur in a particular amount of time today did so five times more slowly in the most ancient quasars.
Time and Space
Time and space intertwine, and the universe has been expanding since the Big Bang. This is according to Einstein’s general theory of relativity.
Astrophysicist Geraint Lewis of the University of Sydney in Australia, lead author of the study published in the journal Nature Astronomy, said this continual expansion explains how time flowed more slowly earlier in the universe’s history relative to today.
It is not as if everything was in slow motion. If someone could transport you back to that time, you would still experience a second as feeling like a second. But from the perspective of a person today, a second back then would unfold in five seconds now.
“In modern physics, time is a complicated thing,” Lewis said. “Dr. Who had it right, that time is best described as ‘wibbly-wobbly, timey-wimey stuff.’ This means that we don’t really understand time and its limitation, and some things are still not ruled out: time travel, warp drives, etc. The future could be very exciting, though maybe not.”
By looking at faraway objects, scientists peer back in time because of how long it takes for light to travel through space.