Researchers at the University of Portsmouth in the UK have proposed a cosmic bounce as an alternative to the Big Bang to explain phenomena such as dark matter. According to this research, relic black holes from before the Big Bang may play a role in shaping today’s galaxies, calling for new cosmological frameworks in light of data from the James Webb Space Telescope (JWST). 

Dark matter is matter that does not reflect or absorb light. It accounts for about 27 percent of the universe’s total mass-energy content and is known to exert its gravitational influence on galaxies and other structures. 

Physicists also refer to it as the glue that holds galaxies together, but do not quite understand it at a fundamental level. Many suggest that it is composed of subatomic particles yet to be discovered.

Enrique Gaztanaga, a researcher at the University of Portsmouth in the UK, points out that ancient black holes that formed before the Big Bang also exhibit the same properties as dark matter. 

Bounce, not a bang

The idea of ancient black holes does not gel well with the concept of the Big Bang, that moment of singularity when the universe was born. Gaztanaga points out that in the singularity, density becomes infinite and laws of physics break down. According to him, this is not a physical reality but a sign that something is missing in our theory. 

Instead, Gaztanaga suggests that, before the Big Bang, the universe underwent a phase of contraction that reached a high but finite density. It then rebounded, beginning a new phase of expansion. In standard cosmology, after the Big Bang, the universe underwent exponential expansion, or inflation, erasing traces of earlier structures. 

In a bouncing universe, though, objects larger than 90 meters (295 feet) could have survived the transitional phase of the bounce and left behind a relic from the previous cosmos. These could be black holes, gravitational waves, and density fluctuations. 

Relic black holes

Gaztanaga suggests two models for how relics from the previous cosmos can survive. The first is direct, but the second one is interesting. In the second scenario, matter clumps under the influence of gravity and forms halos, and then collapses into black holes after the bounce. 

This can happen to galaxies as well as stars that make black holes, losing their structure but retaining their mass. If the cosmic bounce produced a large number of black holes, they could make a significant fraction of dark matter. 

Observations from the JWST show compact, extremely red objects in the early universe. Luminous only for a few hundred million years after the Big Bang, these “little red dots” are unexpectedly massive. 

Physicists believe these tiny dots could be seeds of supermassive black holes at the center of galaxies today. If these seeds existed immediately after the bounce, then the universe was not strictly beginning from scratch, and the supermassive black holes could have originated from them. 

The theory still needs to be tested extensively to replace the Big Bang concept. However, if it is true, our universe did not start all at once and may have rebounded, maybe once or more. All those relics of the previous universes could be shaping the galaxies of today. 

The research findings were published in the journal Physical Review D.