A new theory proposes that the universe may not have begun with a single Big Bang, but rather with a rebound from an earlier contraction. This earlier collapse would have condensed a former universe into a singularity, but some black holes might have survived as 'cosmic fossils' that persist today.
Researchers from the University of Portsmouth’s Institute of Cosmology and Gravitation and the Institute of Space Sciences in Barcelona have published their findings in Physical Review D. They suggest that when the Big Bang occurred, these remnant black holes became part of our universe’s fabric and could help explain mysteries such as dark matter and galaxy formation.
Lead author Professor Enrique Gaztañaga said: 'For almost a century, cosmologists have traced the history of the universe back to a single dramatic moment known as the big bang... But some of the deepest mysteries in physics remain unresolved.' The study explores a 'cosmic bounce' mimicking inflation, with ancient objects surviving from before it.
According to the team, some black holes formed during the earlier cosmic phase and survived the bounce, while others formed shortly after due to amplified density fluctuations. These clumps of matter collapsed more easily under gravity, forming large structures early on.
Singularities, such as those at the centre of black holes, represent a breakdown in Einstein’s general relativity. The new theory avoids this by suggesting the universe collapsed to a high but finite density before rebounding. Professor Gaztañaga added: 'A bounce provides a way for the universe to transition from contraction to expansion without requiring new exotic physics.'
