Almost a century ago, Edwin Hubble noticed that galaxies are rushing apart: the Universe expands. But what was inflating it in the first moments? Inflation theory, born from the ideas of Alan Guth and Andrei Linde, predicted tiny density ripples that later grew into stars. The imprint of those events is preserved in the cosmic microwave background — a faint microwave glow that pervades space. It is captured by radio telescopes and is like an ancient photographic film: develop it, and you see the past.

To decipher this pattern, they used symbolic regression — an algorithm that sifts through millions of formulas and finds the best one, like a child assembling a construction set without instructions. After feeding it spectra from several surveys, the computer identified oscillations that speed up as the wavelength grows. Numerical simulations confirmed that this model fits the data better than standard ones. It seems that in the early universe, a expansion mechanism with jerks was at work — perhaps due to phantom energy that made space jitter.