Intergalactic medium (IGM)

The intergalactic medium (IGM) is the vast, mostly empty space between galaxies, filled with thin gas and plasma. Although extremely diffuse, this gas constitutes a significant portion of the universe's ordinary matter. The IGM plays a crucial role in cosmic evolution by providing the material for galaxy formation and being influenced by phenomena like quasars and supernovae. It also affects how light travels across the universe, helping scientists study the universe's history and structure. Despite its emptiness, the IGM is fundamental to understanding how galaxies and the universe itself develop over billions of years.