Black holes created before the Big Bang may have survived into the Universe we see today, according to new research from the University of Portsmouth. These ancient objects could act as "cosmic fossils" and may even help explain dark matter, the invisible material that plays a major role in shaping galaxies across the Universe. The findings explore the possibility that the Universe did not begin with a single explosive event.
Instead, the researchers investigate cosmic 'bounce' models, in which an earlier Universe contracted before reversing course and expanding. Under this scenario, some black holes from that earlier cosmic phase could have survived the transition and remained present ever since as "cosmic fossils." If the idea proves correct, these primordial black holes could offer clues to several major unanswered questions in cosmology. They might help scientists understand what dark matter is and how the earliest galaxies and other large structures began to form.
Rethinking the Beginning of the Universe Professor Enrique Gaztañaga, lead author of the study from the University of Portsmouth's Institute of Cosmology and Gravitation and the Institute of Space Sciences in Barcelona, said: "For almost a century, cosmologists have traced the history of the Universe back to a single dramatic moment known as the Big Bang. In the standard picture, space and time emerged from an extremely hot, dense state around 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 -- the faint radiation left over from the early Universe -- and accurately predicts how galaxies are distributed across vast cosmic distances. "But some of the deepest mysteries in physics remain unresolved. We still don't know what triggered 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 the invisible 'dark matter' is that outweighs ordinary matter by about five to one.
"Our research explores a possibility that could connect several of these puzzles: the Universe may not have begun with a singular bang at all, but instead emerged from a cosmic bounce mimicking inflation, with some of the oldest objects in the Universe potentially surviving as relics from before it." Some black holes may have originated during the earlier contracting phase and then passed through the bounce. If so, these relics could still affect how galaxies are structured billions of years later. Other black holes may have formed soon after the bounce because density fluctuations were amplified.
In this case, matter in the young Universe would have been distributed in unusually strong concentrations. Those denser regions would have been more likely to collapse under gravity, allowing large cosmic structures (and black holes) to develop earlier than they otherwise might. A Cosmic Bounce Instead of a Singularity According to Einstein's theory of general relativity, tracing the Universe backward leads to the Big Bang singularity, where density becomes infinite, and the known laws of physics no longer work.
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