The Dark Energy Spectroscopic Instrument (DESI) has created the largest high-resolution 3D map of the universe . The work involved observing more than 47 million galaxies and quasars as well as 20 million stars over a five-year period. Researchers will now use the vast dataset to probe the nature of dark energy. DESI, which began collecting data in 2021, is mounted on the Nicholas U Mayall 4-m Telescope at the Kitt Peak National Observatory in Arizona. It comprises 5000 robot-controlled optical fibres that send light to an array of spectrographs. This allows DESI to make an extensive map of galaxies and quasars with the spectroscopic data providing a measure of how fast a galaxy is moving away from us, which is determined by a galaxy’s redshift. By comparing how galaxies clustered in the past with their distribution today, researchers can trace dark energy’s influence. Work published in 2024 found hints that the acceleration of the expansion of the universe has not been constant.…