Enormous 3D map of the universe shows brilliant 'sea of light' near the cosmic dawn

Astronomers created an exceptionally detailed 3D map of the early universe by tracking light emitted from hydrogen atoms when excited by nearby stars, revealing a brilliant "sea of light" that filled the ancient cosmos. Using line-intensity mapping with the Hobby-Eberly Telescope in Texas, researchers captured combined light from entire sky regions rather than individual galaxies, detecting previously hidden faint galactic structures and gas clouds. This approach gathered over 600 million spectra across an area equivalent to 2,000 full moons, providing new insights into how dark energy and gravity shape cosmic evolution.