Universe has fifth dimension: Scientists unravel mystery of black holes
Big Bang relics have five dimensions (photo: Jeremy Perkins)
If the Universe has a fifth dimension, primordial black holes may be longer-lived — physicists from Lehman College in the US have reached this conclusion. According to their model, extremely dense microscopic black holes could interact with an additional dimension, according to a new study that is being prepared for publication in the journal Physical Review D.
The brane concept and the leakage of gravity
Modern theoretical physics views the observable Universe as a four-dimensional membrane (brane) located within an even larger space.
How does it work?
Matter constraints: Elementary particles are confined to the brane and cannot leave the boundaries of four-dimensional space.
The scale of the extra dimension: The fifth dimension is assumed to exist in a compactified state and have a size of about one micron.
How gravity behaves: If a black hole’s event horizon is smaller than one micron, its gravitational field extends into the fifth dimension, turning the object into a five-dimensional one.
Formation mechanisms in the early Universe
Unlike stellar-mass black holes, primordial black holes formed in the first fractions of a second after the Big Bang from extremely dense regions of matter.
Scientists calculated two main formation scenarios.
Rapid phase transitions: As the early Universe cooled rapidly, high-density regions formed.
Calculations confirmed that four-dimensional black holes formed this way would be unstable and would quickly transform into five-dimensional ones due to the so-called Gregory-Laflamme instability.
Cosmic string collapse: Hypothetical defects in spacetime formed loops that contracted under their own tension.
In the dark dimension model, primordial black holes formed from these strings are five-dimensional from the outset.
Impact on the lifespan of cosmic objects
Moving into an additional dimension significantly changes the physical properties and evolution of a black hole.
How exactly?
Slower evaporation: Through Hawking radiation, black holes gradually lose mass.
However, five-dimensional objects evaporate much more slowly than their four-dimensional counterparts, allowing some of them to survive to the present day.
To put this into perspective, the Universe is 13.8 billion years old.
Explaining anomalous signals: Scientists suggest that the final evaporation burst of a five-dimensional black hole could have caused the detection of a high-energy neutrino by the KM3NeT observatory without accompanying photon emission.
Relics from the beginning of time: If even one primordial black hole is detected, physicists will gain a direct tool for studying physical processes and dimensions that cannot be observed directly.
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