Chaotic, messy and agitated. Galaxies that formed just a few hundred million years after the Big Bang looked nothing like the galaxies we see today.

This is what astronomers, led by researchers from the University of Cambridge, found when studying data from the James Webb Space Telescope (JWST). The team analyzed more than 250 young galaxies that existed when the Universe was between 800 million and 1.5 billion years old. By studying the movement of gas within these galaxies, the researchers found that most were turbulent clumps of systems and had not yet evolved into smooth rotating disks like our own galaxy.

The findings, published in the journal Monthly Notices of the Royal Astronomical Society, suggest that galaxies gradually became more calm and organized as the Universe evolved. But in the early Universe, star formation and gravitational instabilities caused such intense turbulence that many galaxies struggled to stabilize.

“We’re not just seeing a few striking exceptions. This is the first time we can see an entire population of galaxies at the same time,” notes the study’s first author, Lola Dunhive, from the Kavli Institute of Cosmology in Cambridge. “We found enormous diversity: some galaxies start to acquire a smooth rotation, but most remain chaotic, with gas expanding and moving in all directions,” he adds.

The researchers used JWST’s NIRCam instrument in a rare mode that can record the faint light from ionized hydrogen gas in distant galaxies. Dunhive developed new software to analyze this data, which was combined with images from other JWST observations to measure how the gas was moving within each galaxy.