Science knows no country, because knowledge belongs to humanity, and is the torch which illuminates the world.
— Louis Pasteur (Louis Pasteur, Free Lance of Science by René Jules Dubos, 1960)

Global 21-cm cosmological signal

Hydrogen is the most abundant element in our Universe, accounting for roughly 74% of all baryonic matter, and was formed very early on, about 3 minutes after the Big Bang in a process called Big Bang Nucleosynthesis. The 21-cm spectral line is associated with the hyperfine splitting of the hydrogen atom ground state...