Plate Nº 12 · recorded October 10, 2026
PhysicsReported finding
Primordial black holes could shift into five dimensions, math suggests
A study published October 5, 2026, in Physical Review D argues that primordial black holes, if they exist, may form and survive as five-dimensional objects rather than ordinary four-dimensional ones.
By Marcus Bennett2 min read498 words
In brief
- Study published October 5, 2026, in Physical Review D
- Led by Luis Anchordoqui of Lehman College, City University of New York
- Hidden dark dimension estimated at roughly a micron wide
- PBHs from cosmic strings could have lifetimes comparable to the age of the universe
- DOI: 10.1103/g12h-93th
A theoretical paper published October 5, 2026, in Physical Review D argues that primordial black holes — if they exist — may form and survive as five-dimensional objects rather than as ordinary four-dimensional ones.
What is a primordial black hole?
Primordial black holes (PBHs) are hypothetical objects that physicists think formed in the early universe rather than from collapsing stars. Ordinary black holes come from dying massive stars; primordial black holes would predate stars altogether. Some cosmologists have proposed PBHs as a possible component of dark matter — the unseen mass that shapes galaxies and holds them together.
No one has yet detected a primordial black hole. Their existence remains an open question.
What is the "dark dimension"?
Standard cosmology describes the universe as four-dimensional: three spatial dimensions (length, height, and depth) plus one dimension of time. The dark dimension scenario adds a fifth, a hidden spatial direction that ordinary matter and forces cannot access.
Gravity, however, could extend into this hidden direction. Researchers estimate the extra dimension at roughly a micron wide — about the thickness of a human hair — yet invisible to everyday physics. Because primordial black holes can be extremely small, the dark dimension could change how they formed and how long they lasted.
How did the team test the idea?
A group led by Luis Anchordoqui of Lehman College, City University of New York, approached the question with theoretical math rather than observation. The researchers applied proposed rules of quantum gravity — the still-incomplete framework describing gravity at subatomic scales — to model how black holes would behave under the dark dimension theory.
They then checked whether these objects would function as standard four-dimensional entities or as five-dimensional ones.
What did the math show?
The numbers produced a peculiar pattern. Some primordial black holes would begin as ordinary four-dimensional objects, then grow unstable and shift into five-dimensional ones. Others, those spawned from cosmic strings — thin, thread-like defects in spacetime predicted by some theories — would start out as five-dimensional.
"In this paper, we revisit the formation mechanisms of PBHs and ask whether, within the dark dimension scenario, PBHs are effectively 4D or 5D black holes," the study authors wrote.
Could any of them survive to today?
The extra dimension also changes how long these objects could last. "We further show that PBHs formed from cosmic strings can have lifetimes comparable to the age of the universe," the researchers reported.
That would make them long-lived enough, in principle, to still exist today. The paper offers no claim that they actually do.
What are the limits of the study?
The analysis is purely theoretical. No telescope or experiment has confirmed the dark dimension, primordial black holes, or PBHs behaving as five-dimensional objects. The work joins two open mysteries — dark matter and extra dimensions — into a single speculative framework.
Real-world proof remains missing.
The study carries the DOI 10.1103/g12h-93th and appears in volume 2026 of Physical Review D.
via Phys.org Space & Astronomy (Source)
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