Magnetic fields that stretch across thousands of light-years should take a very long time to organize. Standard dynamo theory puts that timeline at roughly 5 to 10 billion years in galaxies. Yet astronomers have spotted coherent magnetic fields in galactic and protogalactic environments at high redshifts, including reports up to redshift 2.6 and even 5.6. That mismatch has been a stubborn problem. A new study in Physical Review Letters argues that part of the answer may lie in the chaos of galaxy formation itself. Instead of treating magnetic growth as something that unfolds in a settled system, the researchers looked at what happens while a galaxy is still assembling from a collapsing cloud of ionized gas. “However, dynamo theory has its limitations”, says Pallavi Bhat, an assistant professor at the International Centre for Theoretical Sciences and an author of the study. “In particular, it struggles to explain observations of young galaxies with robust magnetic fields across thousands of light-years”. Collapsing plasma cloud with uniform magnetic field (red). Top Right: Compression alone amplifies the field. Bottom …