A team of scientists, including a Kiwi, have for the first time observed the early universe running in extreme slow motion, unlocking one of the mysteries of Einstein's expanding universe.
Because of the accelerating expansion of space, time in the early universe - when it was just a billion years old, is perceived as being five times slower than it is today.
It's the first time the effect has been observed since it was first predicted by Albert Einstein more than a century ago.
Quasars are supermassive black holes at the centres of early galaxies, and it was by unlocking their mysteries that the team was able to use them as 'clocks' to measure time near the beginning of the universe.
Kathryn speaks to Professor Geraint Lewis, a professor of astrophysics at the University of Sydney and lead author of the study. He worked on this with University of Auckland statistician Brendon Brewer.