Using the James Webb Space Telescope (JWST), an international team of astronomers has found compelling evidence that early galaxies were responsible for the reionization of the early universe. This is the process by which neutral hydrogen atoms are ionized, making the universe transparent to light at wavelengths that would have been absorbed by the atoms. The research was done by members of the EIGER collaboration, which is using the JWST’s Near Infrared Camera (NIRCam) to study light from quasars in the early universe.

https://physicsworld.com/a/jwst-finds-smoking-gun-evidence-of-early-galaxies-transforming-the-universe/