Yes, hydrogen is the most abundant gas in the universe. It is the primary element produced during the Big Bang, which is the initial event that gave rise to the universe as we know it. Hydrogen makes up about 75% of the elemental mass of the universe.
Hydrogen plays a crucial role in stars, particularly in their fusion reactions. In the core of stars like our Sun, hydrogen atoms undergo nuclear fusion, combining to form helium through a process called thermonuclear fusion. This fusion reaction releases a tremendous amount of energy and is the primary source of a star's luminosity.
The fusion process in stars involves the conversion of hydrogen nuclei (protons) into helium nuclei. This fusion occurs at extremely high temperatures and pressures in the stellar core, where hydrogen nuclei collide with enough energy to overcome the electrostatic repulsion between them. This fusion reaction is the fundamental process that powers stars and allows them to shine.
So, not only is hydrogen the most abundant gas in the universe, but it also serves as the fuel for stellar fusion reactions, making it essential for the formation and energy production of stars.