Pathria-Good Black Hole Origin
The first proposal that our universe might exist inside the singularity of a black hole in a parent universe.
Placeholder for a 3D visualisation of Black Hole Genesis. The interactive scene will land in Phase 3. A black hole and a Big Bang both involve singularities; perhaps they are two sides of the same event. The collapse of a sufficiently massive object in a parent universe can produce a new expanding region of spacetime, which from the inside looks like our universe began with a Big Bang.
In one sentence
Pathria and Good independently proposed in 1972 that the universe may be the interior of a black hole, opening a line of thinking that still informs cosmology today.
The claim
In 1972, two researchers working independently noticed something strange. The Schwarzschild radius of a black hole containing the mass of our observable universe is roughly equal to the size of our observable universe. Raj Pathria, a physics professor at Waterloo, and I.J. Good, a Cambridge mathematician who had worked with Alan Turing at Bletchley Park, both speculated that this coincidence might not be accidental.
What if our universe IS the interior of a black hole? From inside, an observer in a sufficiently large black hole would not necessarily notice. There would be a 'beginning' in the past (the formation of the parent black hole) and the matter inside would expand outward away from the singularity. To inhabitants, that expansion would look like a Big Bang.
Pathria and Good's papers were brief, speculative, and stayed mostly on the fringes of cosmology for decades. But the idea did not go away. It seeded the work of Lee Smolin (cosmological natural selection), Afshordi and collaborators (the holographic Big Bang), and a small but persistent strand of black hole cosmology research.
The family stance
A higher-dimensional parent universe existed before ours. Something collapsed in that parent universe, and the gravitational singularity at the center of the resulting black hole became the seed of our universe. We live inside that black hole.
Predictions
- Our universe has finite spatial extent corresponding to a black hole interior
- The 'beginning' is not a singularity but a black hole formation in the parent universe
- A parent universe of higher-dimensional or comparable geometry existed before ours
Evidence
- The numerical coincidence between our universe's mass-energy and a corresponding black hole's Schwarzschild radius
- Conceptually resolves the question of what existed before the Big Bang by relocating it to a parent universe
- Historically opened the line of research that led to current black hole cosmology models
Counterpoints
- Pathria-Good's proposal was speculative and lacked a detailed mechanism for how matter inside the black hole could behave like our observable universe
- The original papers did not specify the geometry of the parent universe or how the black hole formed there
- Has been criticized as relying on a numerical coincidence rather than physical derivation
Variants in this family
▸Go deeperTechnical detail with proper terminology
Pathria's 1972 Nature paper was a brief speculation rather than a developed model. He noted that for a closed universe in standard FRW cosmology, the total mass-energy can be calculated, and the Schwarzschild radius of an equivalent mass is approximately the size of the observable universe.
The technical content of both papers is limited compared to modern black hole cosmology. The substantive development of the idea came decades later in works by Smolin (1992), Easson and Brandenberger (2001), and Afshordi, Mann, Pourhasan (2014).
For the Pathria-Good picture to be physically consistent, the geometry of the parent universe needs to differ from our four-dimensional spacetime in specific ways. This is what Afshordi's holographic Big Bang attempts to provide.
References
- EstablishedPathria, R. K. (1972). Nature 240, 298
- Needs verificationGood, I. J. (1972). Physics Today 25, 15
- EstablishedSmolin, L. (1992). 'Did the universe evolve?' Class. Quantum Grav. 9, 173
Last reviewed May 14, 2026
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