The Big Bang theory has long been the cornerstone of our understanding of the universe’s origin, describing a singular event where all of space, time, and energy emerged from an infinitely dense point. However, a new study led by Professor Enrique Gaztañaga from the Institute of Cosmology and Gravitation at the University of Portsmouth challenges this notion. Published in the journal Physical Review D, the study proposes a “gravitational bounce” model, suggesting that the universe may have been born inside a black hole, replacing the singular Big Bang with a continuous cycle of collapse and rebirth.
This groundbreaking hypothesis posits that our universe could have originated within a massive black hole created in a “parent” universe. As matter collapses inward, quantum mechanics—governing the smallest particles—prevents all matter from occupying the same state, generating pressure that halts the collapse before a singularity forms. This trapped energy then bounces outward, leading to a burst of expansion that forms a new universe.
The End That Becomes a Beginning
The concept, termed the Black Hole Universe model, intertwines gravity and quantum mechanics, illustrating their potential to work in tandem rather than opposition. Gaztañaga explains that the research “looks in, rather than out,” questioning what happens when a massive amount of matter collapses. The outcome suggests that “gravitational collapse does not have to end in a singularity,” and under the right conditions, a bounce becomes not just possible but inevitable.
Quantum Pressure and the Universe’s Rebound
Central to this theory is a straightforward equation describing pressure changes as matter compresses. During collapse, pressure becomes negative, mimicking dark energy, which is believed to drive the universe’s current expansion. This negative pressure causes rapid expansion, resembling the inflation phase cosmologists attribute to the early universe.
The model relies on established physics, such as the degeneracy pressure that prevents white dwarfs and neutron stars from collapsing entirely. As density nears a critical limit, quantum pressure pushes back, creating a bounce radius where contraction stops and expansion begins. This process could explain the universe’s inflationary growth, its nearly flat geometry, and even the acceleration of its expansion, aligning closely with data from the Planck satellite mission.
A Universe Within a Black Hole
From an external viewpoint, collapsing matter resembles an ordinary black hole, with the event horizon capturing everything within. However, inside, matter bounces and inflates, forming a new region of spacetime and concealing a universe like ours. This scenario suggests that every black hole could seed a new universe, implying that our universe might have emerged from such a cosmic womb.
The model predicts a slight but measurable curvature in our universe, akin to a sphere’s surface. Gaztañaga’s team estimates this curvature at approximately –0.07 ± 0.02. Upcoming astronomical surveys could objectively measure this curvature, potentially validating the model.
A Cycle Without Singularities
Classical physics holds that both black holes and the Big Bang culminate in singularities, where density becomes infinite and natural laws break down. These singularities have long troubled cosmologists. However, incorporating quantum effects, as this model does, eliminates singularities.
In this model, the universe’s beginning is a smooth bounce rather than a sharp explosion. Matter compresses into a high-density quantum state, halts its collapse, and then expands. The Big Bang becomes a transition event in a broader cosmic evolution cycle, replacing the mystery of an initial singularity with a bounce mechanism grounded in quantum mechanics and general relativity.
Testing the Bounce With New Eyes
The theory will soon face real-world testing. Gaztañaga is the Science Coordinator for ARRAKIHS, an upcoming European Space Agency mission designed to explore galaxies’ faint outer regions. The spacecraft’s four wide-angle telescopes will probe the distant halo of gas and dark matter, potentially revealing remnants of the early universe’s physical characteristics that deviate from Big Bang predictions.
These observations could provide new insights into the genesis of spacetime, answering whether we emerged from an explosion or a gravitational bounce. Gaztañaga emphasizes the model’s real-world testability, suggesting it could reshape our understanding of dark matter, supermassive black holes, and galaxy formation.
For those who gaze at the night sky, this perspective is profound. The universe’s story may not start with a bang but a pulse, a heartbeat from a deeper cosmic past.
The Practical Impacts of the Research
If the gravitational-bounce model is confirmed, it could revolutionize cosmology. It suggests that singularities do not form and that creation is better described by cycles of collapse and renewal. This view could redefine creation as a process rather than an instantaneous event, potentially unifying gravity with quantum mechanics and guiding future scientific missions like ARRAKIHS.
The model reimagines existence as a living, regenerating system, inviting wonder and contemplation about our role in the cosmos. The research findings are available in Physical Review D.
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