This is one of the corner-stones of the Hot Big Bang model.

It takes nearly 10 million years to burn through the hydrogen and then things heat up and the helium begins fusing together. Stellar nucleosynthesis continues to create heavier and heavier elements, until you end up with iron.

This process is called nucleosynthesis.Its harder and harder to make nuclei with higher masses.

The term nucleosynthesis refers to the formation of heavy elements, atomicnuclei with many protons and neutrons, from the collision of light elements. TheBig Bang theory predicts that the early universe was a very hot place. Onesecond after the Big Bang, the temperature of the universe was roughly 10billion degrees and was filled with a sea of neutrons, protons, electrons,anti-electrons (positrons), photons and neutrinos. As the universe cooled, theneutrons either decayed into protons and electrons or combined with protons tomake deuterium.


But I feel the Big bang theory has some pretty good examples.

The higher the density, the morehelium produced during the nucleosynthesis era.

N2 - We review the cosmology and physics underlying Primordial Nucleosynthesis and survey current observational data in order to compare the predictions of Big Bang Nucleosynthesis with the inferred primordial abundances. From this comparison we report on the status of the consistency of the standard hot big bang model, we constrain the universal density of baryons (nucleons), and we set limits to the numbers and/or effective interactions of hypothetical new "light" particles (equivalent massless neutrinos).


Nucleosynthesis - Universe Today

Stellar nucleosynthesis is the process by which elements are created within stars by combining the and together from the nuclei of lighter elements. All of the atoms in the universe began as hydrogen. Fusion inside stars transforms hydrogen into helium, heat, and radiation. Heavier elements are created in different types of stars as they die or explode.

Big Bang Nucleosynthesis - HyperPhysics Concepts

Elements heavier than lithium are all synthesized in stars. During the latestages of stellar evolution, massive stars burn helium to carbon, oxygen,silicon, sulfur, and iron. Elements heavier than iron are produced in two ways:in the outer envelopes of supergiant stars and in the explosion of a supernovae.

Nucleosynthesis: The Formation of Elements in the …

The term nucleosynthesis refers to the formation of heavier elements, atomic nucleiwith many protons and neutrons, from the fusion of lighter elements. The theory predicts that the early universe was a very hotplace. One second after the Big Bang, the temperature of the universe was roughly 10billion degrees and was filled with a sea of neutrons, protons, electrons, anti-electrons(positrons), photons and neutrinos. As the universe cooled, the neutrons either decayedinto protons and electrons or combined with protons to make deuterium (an of hydrogen). During the first three minutesof the universe, most of the deuterium combined to make helium. Trace amounts of lithiumwere also produced at this time. This process of light element formation in the earlyuniverse is called “Big Bang nucleosynthesis” (BBN).

Nucleosynthesis – The Physics Hypertextbook

Light elements (namely deuterium, helium, and lithium) were produced in thefirst few minutes of the Big Bang, while elements heavier than helium arethought to have their origins in the interiors of stars which formed muchlater in the history of the Universe.