Cosmic web revealed: 3D map shows hidden sea of light in early universe

Space researchers used the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) to produce the largest 3D map of Lyman-alpha light from hydrogen dating to 9–11 billion years ago, exposing a vast “sea of light” between galaxies and outlining the cosmic web. By applying Line Intensity Mapping to thousands of spectra, the team mapped faint hydrogen gas beyond bright galaxies, shedding light on how gas accreted, galaxies formed, and the large-scale structure of the early universe.