The universe may have had a “secret life” before the Big Bang, a recent study has revealed. The research, published in the Journal of Cosmology and Astroparticle Physics, suggests that the universe underwent a contraction phase before the Big Bang, which led to the formation of black holes that could be the source of dark matter.

This “bouncing” cosmology theory, if proven true, could fundamentally change our understanding of the universe, particularly concerning black holes and dark matter.

Bouncing Between Phases

Traditionally, cosmologists have believed that the universe began with a singular event known as the Big Bang, which was followed by rapid expansion. However, this new research posits a different scenario where the universe first underwent a phase of contraction, reaching a highly dense state before “bouncing” back into expansion. This rebound, according to the study, could have significant implications for the formation of black holes and the mysterious dark matter that makes up about 80% of the universe’s matter.

Dark Matter and Black Holes

The study suggests that during the universe’s contraction phase, small black holes could have formed from density fluctuations. These primordial black holes, surviving through the rebound and into the current expansion phase, might constitute dark matter. The existence of these black holes could explain why dark matter, which does not interact with light, has been so elusive to scientists.

“Small primordial black holes can be produced during the very early stages of the universe, and if they are not too small, their decay due to Hawking radiation will not be efficient enough to get rid of them, so they would still be around now,” said Patrick Peter, director of research at the French National Centre for Scientific Research (CNRS). “Weighing more or less the mass of an asteroid, they could contribute to dark matter, or even solve this issue altogether.”

Future Observations

The hypothesis is still in its early stages, but the researchers are optimistic that future gravitational wave observatories, such as the Laser Interferometer Space Antenna (LISA) and the Einstein Telescope, will be able to detect the gravitational waves produced during the formation of these primordial black holes. Such detections could provide crucial evidence to support the theory that these black holes are indeed dark matter.

While it may take more than a decade before the necessary observations can be made, this new study opens up exciting possibilities about the universe’s origins and the true nature of dark matter.

This handout photograph released by the CEA on September 7, 2023, shows a 3D representation of the galaxy “Bubble”, coloured in brown. The image shows the position of the Milky Way, with a small white dot located outside the bubble on the right, in a white cloud. The blue wisps represent the “cosmic web”, the filaments of galaxies that make up other large structures in the Universe, such as Laniakea.
| Photo Credit: AFP

Astronomers have discovered the first “bubble of galaxies,” an almost unimaginably huge cosmic structure thought to be a fossilised remnant from just after the Big Bang sitting in our galactic backyard.

The bubble spans a billion light years, making it 10,000 times wider than the Milky Way galaxy.

Yet this giant bubble, which cannot be seen by the naked eye, is a relatively close 820 million light years away from our home galaxy, in what astronomers call the nearby universe.

The bubble can be thought of as “a spherical shell with a heart,” Daniel Pomarede, an astrophysicist at France’s Atomic Energy Commission, told AFP.

Inside that heart is the Bootes supercluster of galaxies, which is surrounded by a vast void sometimes called “the Great Nothing”.

The shell contains several other galaxy superclusters already known to science, including the massive structure known as the Sloan Great Wall.

Pomarede said the discovery of the bubble, which is described in research he co-authored that was published in The Astrophysical Journal this week, was “part of a very long scientific process”.

It confirms a phenomenon first described in 1970 by US cosmologist — and future physics Nobel winner — Jim Peebles.

He theorised that in the primordial universe — then a stew of hot plasma — the churning of gravity and radiation created sound waves called baryon acoustic oscillations (BAOs).

As the sound waves rippled through the plasma, they created bubbles.

Around 380,000 years after the Big Bang the process stopped as the universe cooled down, freezing the shape of the bubbles.

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The bubbles then grew larger as the universe expanded, similar to other fossilised remnants from the time after the Big Bang.

Astronomers previously detected signals of BAOs in 2005 when looking at data from nearby galaxies.

But the newly discovered bubble is the first known single baryon acoustic oscillation, according to the researchers.

‘Unexpected’

The astronomers called their bubble Ho’oleilana — “sent murmurs of awakening” — taking the name from a Hawaiian creation chant.

The name came from the study’s lead author Brent Tully, an astronomer at the University of Hawaii.

The bubble was discovered by chance, as part of Tully’s work searching through new catalogues of galaxies.

“It was something unexpected,” Pomarede said.

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Tully said in a statement that the bubble is “so huge that it spills to the edges of the sector of the sky that we were analysing”.

The pair enlisted the help of Australian cosmologist and BAO expert Cullan Howlett, who “mathematically determined the spherical structure which best corresponded to the data provided,” Pomarede said.

This allowed the trio to visualise the three-dimensional shape of Ho’oleilana — and the position of the archipelagos of galaxies inside it.

It may be the first, but more bubbles could soon be spotted across the universe.

Europe’s Euclid space telescope, which launched into July, takes in a wide view of the universe, potentially enabling it to snare some more bubbles.

Massive radio telescopes called the Square Kilometre Array, being built in South Africa and Australia, could also offer a new image of galaxies from the viewpoint of the Southern Hemisphere, Pomarede said.