Until then, light was trapped in a plasma of ions, so that the universe was a milky and opaque place. But when atoms formed, light could escape from the plasma and flow freely, making the universe transparent. Then atoms formed molecules, molecules formed gas clouds, and after 106 years gas clouds formed stars. The Higgs field, an energy field which permeates the universe, has a certain energy density today. Nirmal Raj is an assistant professor of theoretical physics at the Centre for High Energy Physics in the Indian Institute of Science, Bengaluru, and tweets at @PhysicsNirmal.

Source: The Hindu January 24, 2024 16:44 UTC