Quasar “clocks” show that the universe was about five times slower shortly after the Big Bang

Scientists have noticed for the first time that the early universe moved in extremely slow motion, unlocking one of Einstein’s expanding universe mysteries. Research published in natural astronomy. Einstein’s general theory of relativity means that we should observe the distant, and therefore ancient, universe running much more slowly than it does today. However, looking back at that time has proven elusive. Scientists have now been able to solve this mystery by using quasars as “clocks.” said the study’s lead author, Professor Geraint Lewis from the University of Sydney’s School of Physics and the Sydney Institute of Astronomy.

“If you were out there, in this infant universe, a second would seem like a second, but from our location, more than 12 billion years in the future, that early time appears to be slowing down.” Professor Lewis and co-author Dr Brendon Brewer from the University of Auckland used observed data from nearly 200 quasars (supermassive black holes at the centers of early galaxies) to analyze this time dilation. “Thanks to Einstein, we know that time and space are intertwined, and since the dawn of time at the Big Bang singularity, the universe has been expanding,” said Professor Lewis.

“This expansion of space means that our observations of the early universe should appear much slower than current time flows. “In this article, we take it back to about a billion years after the Big Bang.” Previously, astronomers had confirmed the return of this slow universe to about half the age of the universe by using supernovae (exploding massive stars) as “standard clocks.” But although supernovae are very bright, they are difficult to observe at the enormous distances required to observe the early universe. Looking at quasars, this time horizon has receded to only a tenth of the age of the universe, confirming that the universe appears to be accelerating as it ages. Professor Lewis said: “Where supernovae act as a single flash of light, making them easier to study, quasars are much more complex, like a continuous fireworks display. “What we have done is unravel this fireworks display and show that quasars can also be used as standard time markers for the early universe.”

Professor Geraint Lewis is at the Sydney Institute of Astronomy in the Faculty of Physics at the University of Sydney. Credit: University of Sydney Professor Lewis worked with astrophysicist Dr Brewer to examine in detail 190 quasars observed over two decades. By combining observations taken in different colors (or wavelengths) (green light, red light, and infrared), they were able to unify the “beats” of each quasar. By applying Bayesian analysis, they found that the expansion of the universe is imprinted in the ticking of each quasar. “With these remarkable data, we were able to plot the ticks of the quasar clock, revealing the effect of the expansion of space,” said Professor Lewis.

Estos resultados también confirman la imagen de Einstein de la expansión del universo, pero contradicen estudios previos que no lograron cuantificar la dilatación del tiempo de cuásares distantes.

«Estos estudios previos han llevado a la gente a preguntarse si los cuásares son realmente objetos cósmicos, o incluso si la idea de expandir el espacio es correcta», dijo el profesor Lewis.

«Con estos nuevos datos y análisis, pudimos encontrar el escurridizo signo de los cuásares y se comportan exactamente como predijo la relatividad de Einstein», dijo.

source: https://www.nature.com/articles/s41550-023-02029-2