Ian Smail

In the distant universe, when it was just a couple of billion years old, many galaxies resembled boiling cauldrons: gas clumped so quickly that stars ignited one after another, and dust heated up and shone brightly in the submillimeter range.

A filament of the cosmic web stretches through the young universe, and strung along it like beads on a necklace are galaxies. In the core of the SSA22 protocluster, which in a few billion years will become the center of a massive cluster, these beads are still hot and dusty: stars are being born inside them, and cold gas serves as fuel.