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In the years immediately before World War II, Hans Bethe first elucidated those nuclear mechanisms by which hydrogen is fused into helium. Fred Hoyle's original work on nucleosynthesis of heavier elements in stars, occurred just after World War II. [4] His work explained the production of all heavier elements, starting from hydrogen.
However, forming helium-4 requires the intermediate step of forming deuterium. Before nucleosynthesis began, the temperature was high enough for many photons to have energy greater than the binding energy of deuterium; therefore any deuterium that was formed was immediately destroyed (a situation known as the "deuterium bottleneck").
Indeed, there is no obvious reason outside of the Big Bang that, for example, the young universe before star formation, as determined by studying matter supposedly free of stellar nucleosynthesis products, should have more helium than deuterium or more deuterium than 3 He, and in constant ratios, too. [106]: 182–185
The Primordial Era is defined as "−50 < n < 5". In this era, the Big Bang, the subsequent inflation, and Big Bang nucleosynthesis are thought to have taken place. Toward the end of this age, the recombination of electrons with nuclei made the universe transparent for the first time.
Even before recombination and decoupling, matter began to accumulate around clumps of dark matter. [ 10 ] : 4.1 Clouds of hydrogen collapsed very slowly to form stars and galaxies , so there were few sources of light and the emission from these sources was immediately absorbed by hydrogen atoms.
c. 0 seconds (13.799 ± 0.021 Gya): Planck epoch begins: earliest meaningful time. Conjecture dominates discussion about the earliest moments of the universe's history. The Big Bang occurs in which ordinary space and time develop out of a primeval state (possibly a virtual particle or false vacuum) described by a quantum theory of gravity or "Theory of everything".
Supernova nucleosynthesis is the nucleosynthesis of chemical elements in supernova explosions.. In sufficiently massive stars, the nucleosynthesis by fusion of lighter elements into heavier ones occurs during sequential hydrostatic burning processes called helium burning, carbon burning, oxygen burning, and silicon burning, in which the byproducts of one nuclear fuel become, after ...
In physical cosmology, the photon epoch was the period in the evolution of the early universe in which photons dominated the energy of the universe. The photon epoch started after most leptons and anti-leptons were annihilated at the end of the lepton epoch, about 10 seconds after the Big Bang. [1]