New research by Professor Enrique Gaztanaga of the University of Portsmouth and the Institute of Space Sciences in Barcelona suggests that some black holes formed before the Big Bang and survived the cosmic ‘bounce’, potentially explaining dark matter, the gravitational wave background, and the early growth of supermassive black holes and galaxies.
Gaztanaga proposes a new dark matter mechanism in which relic black holes arise from a pre-big-bounce collapse stage.
“For almost a century, cosmologists have traced the history of the universe back to a single dramatic moment known as the Big Bang,” Professor Gastanaga said.
“The standard picture is that space and time emerged from an extremely hot and dense state about 13.8 billion years ago, followed by billions of years of continued expansion of the universe and galaxy formation.”
“This model has been a remarkable success. It accounts for the cosmic microwave background (CMB), the faint radiation left over from the early universe, and accurately predicts how galaxies are distributed over vast distances in the universe.”
“But some of the deepest mysteries of physics remain unsolved. We still don’t know what caused the Big Bang, why the universe began in such a special state, what caused the brief burst of rapid expansion known as inflation, or what invisible dark matter is that outnumbers ordinary matter by about 5 to 1.”
“Our research explores the possibility of tying some of these puzzles together: the universe never began with a single shock, but may have emerged from a cosmic bounce that mimicked inflation, and some of the universe’s oldest objects potentially survive as relics of an earlier era.”
Some black holes may have formed during the early cosmic stages and survived the bounce, leaving behind relics that may still influence the structure of galaxies billions of years later.
Others may have formed immediately after reflections due to amplified density fluctuations, and matter in the early universe was unevenly distributed in stronger, more pronounced clumps than usual.
These strengthened clumps of matter collapse more easily under their own gravity, making it more likely that large cosmic structures, and black holes, will form early.
In Einstein’s theory of general relativity, the Big Bang corresponds to a singularity, a point at which density becomes infinite and the known laws of physics break down.
Many physicists interpret this as a sign that our current description of the universe’s earliest moments is incomplete.
One other idea is bounce cosmology. In this cosmology, our universe originates from a very large cloud that first contracts and then rebounds and expands.
Rather than collapsing into an infinite singularity, the universe reaches a very high but finite density before reversing its motion.
“Singularities often indicate that a theoretical description has reached its limits,” Professor Gastanaga said.
“Bounces provide a way for the universe to go from contraction to expansion without requiring new and exotic physics.”
Scientists suggest that this bounce could arise naturally from quantum physics. At very high densities, quantum effects create powerful pressures that prevent matter from being compressed infinitely. This phenomenon already stabilizes dense objects such as white dwarfs and neutron stars, reproducing the inflationary expansion phase.
New models suggest similar effects could occur on a cosmic scale. As the universe contracts, this quantum pressure can stop the collapse and cause a backlash against expansion.
This bounce could also explain two of the biggest mysteries in cosmology.
First, it may explain why the early Universe expanded so rapidly and evenly in all directions.
Second, it could help explain why the universe appears to be expanding at an accelerating rate today, an effect currently thought to be due to a poorly understood force called dark energy.
One notable suggestion is that some structures formed during the collapse phase may have survived after the bounce.
New calculations suggest that compact objects larger than about 90 meters in size may pass through the transition and reappear as former fossils in the expanding universe.
Possible artifacts include gravitational waves, density fluctuations, and ancient black holes.
These relic black holes could help explain dark matter, the invisible matter that shapes the large-scale structures of galaxies and the universe.
If large numbers form during the bounce, they could account for a significant portion, or even all, of the dark matter.
This idea may also help explain the recent discovery by the NASA/ESA/CSA James Webb Space Telescope of an unexpectedly massive object (sometimes called a tiny red dot) in the early Universe.
Many astronomers suspect that these sources are related to rapidly growing black holes that appeared shortly after the Big Bang.
“If a supermassive black hole already existed immediately after the bounce, we wouldn’t have to start from scratch when building the first galaxies in the early universe,” Gastanaga said.
The theory also makes predictions that may be tested by future observations.
Scientists may be able to look for relic gravitational waves from earlier cosmic stages, or subtle patterns in the CMB that preserve traces of a pre-Big Bang universe.
“Much work remains to test these ideas,” Professor Gastanaga said.
“But if the universe experienced a bounce, the dark structures that shape today’s galaxies could be remnants of the space age that preceded the Big Bang.”
His paper was published in the magazine Physical Review D.
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Enrique Gastanaga. 2026. Cosmological Bounce Relics: Black Holes, Gravitational Waves, and Dark Matter. Physics. Rev.D 113, 043544; 2: 10.1103/pr4p-6m49
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