A new model unifies the pre-inflationary epoch and inflation within a single scalar field. An early decelerated expansion transitions into acceleration, which naturally suppresses large-scale correlations in the cosmic microwave background (θ > 60°) noticed by the Planck satellite. Analysis of quantum fluctuations in the Mukhanov-Sasaki formalism showed that the spectrum has a natural cutoff on large scales, since the vacuum state is defined only for perturbations that fit inside the horizon at the start of inflation. Meanwhile, on small scales, the standard scale-invariant pattern is recovered.
The birth of the universe resembles not an explosion, but a traffic jam. At first, a tiny fraction of a second after the Big Bang, space expanded sluggishly, like cars stuck in gridlock. Then came a sharp surge—accelerated expansion, which cosmologists call inflation. This contrasting transition explains an ancient mystery: why there are no large spots in the snapshot of the universe's microwave 'echo.' The slow phase acted like a filter, preventing large energy fluctuations from growing. Only fine ripples remained—the very quantum jolts from which galaxies later emerged. Remarkably, without such a jam, the familiar cosmos might never have formed: all matter would have collapsed into giant black holes or remained a diffuse fog. The new model, consistent with Planck satellite data, was developed by Alan Guth and others. Yet back in the 1940s this 'echo' was predicted by George Gamow, and in 1965 it was serendipitously detected by Arno Penzias and Robert Wilson.
🎯 A delay in the first minuscule fraction of a second shaped the cosmos: without this 'cosmic traffic jam,' stars might never have ignited at all.