Tiny Black Holes Don’t Warp the Cosmos ⚡ экспресс
In inflationary models, the birth of primordial black holes requires a sharp spike in perturbations on small scales — for example, via a phase of ultra-slow roll. The question arises: won't these tiny perturbations spoil the statistics of large-scale inhomogeneities recorded in the cosmic microwave background? Using the 'separate universes' formalism (each patch evolves independently), it has been shown that the back-reaction on observable large scales is vanishingly small at the one-loop level. It's like a game of dice where the outcome at one corner of the table doesn't depend on the players at the other. Result: the large-scale picture remains clean.
Right after the Big Bang, the Universe expanded incredibly fast — this phase was called inflation. In some microscopic regions, matter randomly clumped so much that it collapsed into primordial black holes. They are tiny — the size of a proton, yet as massive as an iceberg.
Scientists were tormented by the question: wouldn’t these turbulent small-scale processes spoil the delicate picture of large-scale waves we observe in the cosmic microwave background? Alan Guth soothed: the basses and flutes in the cosmic symphony play at different frequencies and don’t interfere with each other. New calculations proved that any back-reaction is a thousand times weaker than the sensitivity threshold of our instruments. The melody of the cosmos remains pure.
Thus primordial black holes earned the right to be considered part of dark matter — the invisible substance that holds galaxies together. The irony is that, according to Stephen Hawking’s calculations, ordinary black holes evaporate, while these long-lived ones will exist forever.
🎯 A black hole the size of a proton has the mass of an iceberg.