Further support comes from the consistency of the other light element abundances for one particular baryon density and an independent measurement of the baryon density from the anisotropies in the cosmic microwave background radiation. The atoms in your body — apart from the hydrogen — were Cosmic nucleosynthesis made in stars … by stellar nucleosynthesis.
The capture of a neutron Cosmic nucleosynthesis the mass of a nucleus; subsequent radioactive beta decay converts a neutron into a proton with ejection of an electron and an antineutrinoleaving the mass practically unchanged.
One consequence of this is that, unlike helium-4, the amount of Cosmic nucleosynthesis is very sensitive to initial conditions. This graph is a corrected version of one from this LBL page. The mass fraction in various isotopes vs time is shown at right.
Or more precisely, allowing for the finite precision of both the predictions and Cosmic nucleosynthesis observations, one asks: Burbidge, Fowler, and Hoyle. Species of the same element, or isotopes, in addition, differ from each other in mass or on the basis of the number of neutrons neutral fundamental particles in their nuclei.
Furthermore, one value of this baryon density can explain all the abundances at once. It is now known that the elements observed in the Universe were created in either of two ways.
Although 4He continues to be produced by stellar fusion and alpha decays and trace amounts of 1H continue to be produced by spallation and certain types of radioactive decay, most of the mass of the isotopes in the universe are thought to have been produced in the Big Bang. More recently, the question has changed: See Article History Nucleosynthesis, production on a cosmic scale of all the species of chemical elements from perhaps one or two simple types of atomic nuclei, a process that entails large-scale nuclear reactions including those in progress in the Sun and other stars.
The problem here again is that deuterium is very unlikely due to nuclear processes, and that collisions between atomic nuclei are likely to result either in the fusion of the nuclei, or in the release of free neutrons or alpha particles.
The discrepancy is a factor of 2. BurbidgeFowler and Hoyle  is a well-known summary of the state of the field in A very few helium nuclei combine into heavier nuclei giving a small abundance of Li7 coming from the Big Bang.
Specifically, the theory yields precise quantitative predictions for the mixture of these elements, that is, the primordial abundances at the end of the big-bang. Cameronand Donald D.
This has been done to put limits on the mass of a stable tau neutrino.
Helium nuclei, in turn, can be built up into carbon three helium nucleioxygen four helium nucleiand other heavier elements. There are several different nuclear reaction cycles, or processes e.Cosmic Nucleosynthesis Nuclear reactions in primordial nucleosynthesis The ratios of elements found in the oldest gas clouds in the universe contain one of the primary pieces of evidence for the Big Bang.
Big Bang Nucleosynthesis Gamow, Alpher and Herman proposed the hot Big Bang as a means to produce all of the elements. However, the lack of stable nuclei with atomic weights of 5 or 8 limited the Big Bang to producing hydrogen and helium. Nucleosynthesis requires a high-speed collision, which can only be achieved with very high temperature.
The minimum temperature required for the fusion of hydrogen is 5 million degrees. Elements with more protons in their nuclei require still higher temperatures.
There are other ways new nuclei can be created, in the universe (other than BBN and stellar nucleosynthesis); for example, when a high energy particle (a cosmic. Nucleosynthesis: Nucleosynthesis, production on a cosmic scale of all the species of chemical elements from perhaps one or two simple types of atomic nuclei, a process that entails large-scale nuclear reactions including those in progress in the Sun and other stars.
The Big Bang Nucleosynthesis theory predicts that roughly 25% the mass of the Universe consists of Helium. It also predicts about % deuterium, and even smaller quantities of lithium. The important point is that the prediction depends critically on the density of baryons (ie neutrons and protons) at the time of nucleosynthesis.Download