Where does hydrogen from in the early Universe come from?

Answer 1

An excellent question, and we'd be lying if we said we KNEW the answer.

There are several models of the "big bang" and alternative models for the origin of the universe, but the most common is that the universe, at the instant of creation, was filled with a very high density of energy. Energy and mass are interchangeable; that's part of Einstein's theory of general relativity. So with high energy density, some of that energy will convert itself into mass, and the remaining energy causes the mass to expand in all directions. We suspect that 95% or more of the mass was simple hydrogen, with the remainder mostly helium with a little lithium thrown in. Every HEAVIER element, like iron or oxygen or calcium, was created in the cores of stars later on. So the oxygen that we breathe and the iron in your blood was forged in a star. That mass was blasted into space to become the Earth, and us, when the star exploded in a supernova.

Answer 2

Hydrogen in the early universe primarily originated from the process of Big Bang nucleosynthesis. This was an important phase in the evolution of the universe where hydrogen and helium nuclei were formed in the first few minutes after the Big Bang. Subsequently, stars and galaxies further enriched the universe with hydrogen through stellar nucleosynthesis processes.