The findings cast doubt on previous theories of galaxy formation by demonstrating that star production in the early Universe was significantly more efficient than believed. Scientists prefer the theoretical model that galaxies develop over time in huge halos of dark matter.

Astronomers have identified three ultra-massive galaxies -- nearly as massive as the Milky Way -- already in place within the first billion years after the Big Bang. This surprising discovery was made possible by the James Webb Space Telescope's FRESCO program,