Black Holes from Before Big Bang Could Still Exist Today as ‘Cosmic Fossils’

New research led by Professor Enrique Gaztañaga of the University of Portsmouth and the Barcelona Institute of Space Sciences suggests that some black holes formed before the Big Bang and survived a cosmic ‘bounce’, potentially explaining dark matter, gravitational waves and the early growth of supermassive black holes and galaxies.

Gaztañaga proposes a new dark matter mechanism in which relic black holes originate from a collapse phase preceding the Big-Bounce.

“For almost a century, cosmologists have traced the history of the Universe back to a single dramatic moment known as the Big Bang,” Professor Gaztañaga said.

“In the standard picture, space and time emerged from an extremely hot and dense state about 13.8 billion years ago, followed by billions of years of cosmic expansion and galaxy formation.”

“This model has been remarkably successful. It explains the cosmic microwave background (CMB) – the faint radiation left behind by the early Universe – and accurately predicts how galaxies are distributed over vast cosmic distances.”

“But some of the deepest mysteries of physics remain. We still don’t know what started 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 outnumbering ordinary matter by about five to one.”

“Our research explores a possibility that could connect several of these puzzles: the Universe may not have started with a singular bang, but rather emerged from a cosmic rebound mimicking inflation, with some of the oldest objects in the Universe potentially surviving as relics from before it.

Some black holes may have formed during the earlier cosmic phase and survived the rebound, leaving behind relic objects that could still influence the structure of galaxies billions of years later.

Others could form soon after the rebound due to amplified density fluctuations, where matter in the early Universe was unevenly distributed in stronger, more pronounced clusters than usual.

These enhanced clumps of matter would collapse more easily under their own gravity, making the early formation of large cosmic structures – and black holes – more likely.

In Einstein’s theory of general relativity, the Big Bang corresponds to a singularity: a point where density becomes infinite and the known laws of physics break down.

Many physicists interpret this as a sign that our current description of the early Universe is incomplete.

An alternative idea is a bouncing cosmology, in which our Universe originates from a very large cloud that first contracts and then rebounds into expansion.

Instead of collapsing into an infinite singularity, the Universe reaches a very high but finite density before reversing its motion.

“Singularities often indicate that our theoretical description has reached its limits,” Professor Gaztañaga said.

“A rebound allows the Universe to move from contraction to expansion without requiring exotic new physics.”

Scientists suggest this rebound could come naturally from quantum physics. At extremely high densities, quantum effects create a powerful pressure that prevents matter from being compressed indefinitely – a phenomenon that already stabilizes dense objects such as white dwarfs and neutron stars and reproduces the inflationary expansion phase.

In the new model, a similar effect could occur on a cosmic scale. As the Universe contracts, this quantum pressure could stop the collapse and trigger a rebound toward expansion.

This rebound could also explain two of the biggest mysteries in cosmology.

First, it could explain why the early Universe expanded so quickly and uniformly in all directions.

Second, it could shed light on why the Universe appears to be accelerating its expansion today, an effect currently attributed to a poorly understood force called dark energy.

A striking implication is that some structures formed during the collapse phase may have survived the rebound.

The new calculations suggest that compact objects measuring more than about 90 m could go through the transition and reappear in the expanding Universe as fossils from before.

Possible relics include gravitational waves, density fluctuations and ancient black holes.

These relic black holes could help explain dark matter, the invisible substance that shapes galaxies and the large-scale structure of the Universe.

If large numbers formed during the rebound, they could make up a significant fraction, or even all, of the dark matter.

This idea could also help explain recent discoveries by the NASA/ESA/CSA James Webb Space Telescope of unexpectedly massive objects in the early Universe, sometimes nicknamed little red dots.

Many astronomers suspect that these sources are linked to fast-growing black holes, which appeared surprisingly soon after the Big Bang.

“If massive black holes already existed immediately after the bounce, the early Universe would not need to start from scratch when building the first galaxies,” Professor Gaztañaga said.

The theory also makes predictions that could be tested with future observations.

Scientists could search for relic gravitational waves from a previous cosmic phase or for subtle patterns in the CMB that preserve traces of the Universe before the Big Bang.

“Much more needs to be done to test these ideas,” Professor Gaztañaga said.

“But if the Universe was indeed experiencing a rebound, the dark structures that shape galaxies today could be remnants of a cosmic epoch before the Big Bang.”

His article was published in the journal Physical examination D.

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Enrique Gaztañaga. 2026. Relics of cosmological rebound: black holes, gravitational waves and dark matter. Phys. Rev. D 113, 043544; doi: 10.1103/pr4p-6m49