Representation of the hierarchical model of the ingredients that make up the large-scale Universe. The connections between the quantities of intergalactic gas, dark matter and neutral hydrogen allow us to predict, thanks to the computational model developed, the absorption flow of the Lyman-alpha forest, a pattern of lines in the spectra of distant galaxies and quasars that is produced when the light emitted by these objects is absorbed, along its path, by clouds of hydrogen gas. Credit: Francesco Sinigaglia