A Chain Reaction of Black Holes Generates Gravitational Waves express
Right after the Big Bang, primordial black holes floated in the hot plasma — clumps of mass the size of a mountain squeezed into the volume of an atom. According to Hawking's prediction, they slowly evaporated, emitting radiation like tiny stoves. But this heat didn't dissipate without a trace: hitting dense plasma clumps, it nudged them toward collapse. Thus, a new hole was born in place of the evaporated one. The process repeated, and a front of black hole birth raced across the universe — exactly like a forest fire where each burning tree ignites its neighbors. The universe’s expansion acted like a downpour: as it cooled, the plasma became too rarefied, and the chain reaction fizzled out. As a memento, it left behind a characteristic low-frequency hum of spacetime — gravitational waves carrying a sharp cutoff signature. Detectors like LISA could pick up this signal: below a certain frequency, deafening silence, as if someone abruptly stopped the recording. Astonishingly, evaporation — usually the death of a black hole — became a mechanism of multiplication in the early universe.
Original abstract
as written by the authors arXiv:2511.18110
We propose and analyze an autocatalytic mechanism in which bursts of Hawking radiation from evaporating micro-primordial black holes (PBHs) trigger the collapse of near-critical plasma overdensities. In a primordial plasma seeded with such patches, this feedback self organizes into a traveling ignition front that successively forms new PBHs and then self-quenches as the Universe expands. A minimal reaction-diffusion model yields conservative criteria for ignition and freeze-out and predicts a stochastic gravitational-wave background with a sharp causal low-frequency edge set by the freeze-out correlation length and largely insensitive to Planck-scale PBH endpoint microphysics. The resulting sub-Hz-to-audio band and amplitudes satisfy cosmological energy-injection bounds, providing a clean, testable target for forthcoming gravitational-wave observatories.
The expansion of the universe acts like a downpour on a forest fire; once the plasma becomes too rarefied, the chain reaction cuts off, imprinting a sharp silence onto gravitational waves at low frequencies.
In sci-fi, self-replicating objects — from replicators to 'grey goo' — often lead to disasters. Here, black holes become cosmic replicators, but only at the dawn of time.