The Big Bang

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Big Bang nucleosynthesis:

• the description of "process at the Big Bang when the hot-dense universe acted as a giant thermonuclear reactor converting hydrogen to helium with traces of deuterium and lithium" doesn't explain where this element originated, yet this gas is everywhere. Hydrogen is the simplest atomic combination known: a single proton with one associated electron and makes up the 'atmosphere' (or interstellar medium) of galaxies. This is both the source of clouds that create new stars and the repository of gas outflow from existing stars. Locally, this 'atmosphere' is more extensive than the visible Milky Way and governs its development by determining where new stars will form and their composition.

Hydrogen Sky
Big Bang Expanded