Big bang nucleosynthesis

Advertisement Scientific American astronomy editor George Musser explains. This question really has two parts.

Big bang nucleosynthesis

Due to the extreme conditions and the violence of its very early stages, it arguably saw more activity and change during the first second than in all the billions of years since.

From our current understanding of how the Big Bang might have progressed, taking into account theories about inflationGrand Unificationetc, we can put together an approximate timeline as follows: This is the closest that current physics can get to the absolute beginning of time, and very little can be known about this period.

General relativity proposes a gravitational singularity before this time although even that may break down due to quantum effectsand it Big bang nucleosynthesis hypothesized that the four fundamental forces electromagnetismweak nuclear forcestrong nuclear force and gravity all have the same strength, and are possibly even unified into one fundamental forceheld together by a perfect symmetry which some have likened to a sharpened pencil standing on its point i.

The force of gravity separates from the other fundamental forces which remain unifiedand the earliest elementary particles and antiparticles begin to be created. Triggered by the separation of the strong nuclear forcethe universe undergoes an extremely rapid exponential expansion, known as cosmic inflation.

The linear dimensions of the early universe increases during this period of a tiny fraction of a second by a factor of at least to around 10 centimeters about the size of a grapefruit. As the strong nuclear force separates from the other two, particle interactions create large numbers of exotic particlesincluding W and Z bosons and Higgs bosons the Higgs field slows particles down and confers mass on them, allowing a universe made entirely out of radiation to support things that have mass.

Quarkselectrons and neutrinos form in large numbers as the universe cools off to below 10 quadrillion degrees, and the four fundamental forces assume their present forms.

Big bang nucleosynthesis

Quarks and anti quarks annihilate each other upon contact, but, in a process known as baryogenesis, a surplus of quarks about one for every billion pairs survives, which will ultimately combine to form matter.

The temperature of the universe cools to about a trillion degrees, cool enough to allow quarks to combine to form hadrons like protons and neutrons. Electrons colliding with protons in the extreme conditions of the Hadron Epoch fuse to form neutrons and give off massless neutrinoswhich continue to travel freely through space today, at or near to the speed of light.

Some neutrons and neutrinos re-combine into new proton - electron pairs. The only rules governing all this apparently random combining and re-combining are that the overall charge and energy including mass - energy be conserved. Lepton Epoch, from 1 second to 3 minutes: After the majority but not all of hadrons and antihadrons annihilate each other at the end of the Hadron Epoch, leptons such as electrons and antileptons such as positrons dominate the mass of the universe.

As electrons and positrons collide and annihilate each other, energy in the form of photons is freed up, and colliding photons in turn create more electron - positron pairs.

Nucleosynthesisfrom 3 minutes to 20 minutes: The temperature of the universe falls to the point about a billion degrees where atomic nuclei can begin to form as protons and neutrons combine through nuclear fusion to form the nuclei of the simple elements of hydrogen, helium and lithium.

After about 20 minutes, the temperature and density of the universe has fallen to the point where nuclear fusion cannot continue. Photon Epoch or Radiation Dominationfrom 3 minutes toyears: During this long period of gradual cooling, the universe is filled with plasmaa hot, opaque soup of atomic nuclei and electrons.

After most of the leptons and antileptons had annihilated each other at the end of the Lepton Epoch, the energy of the universe is dominated by photonswhich continue to interact frequently with the charged protonselectrons and nuclei.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. Burbidge, Burbidge, Fowler and Hoyle worked out the nucleosynthesis processes that go.

Big Bang Nucleosynthesis was incapable to produce heavier atomic nuclei such as those necessary to build human bodies or a planet like the earth. Instead, those nuclei were formed in the interior of stars.

The very early universe Inhomogeneous nucleosynthesis. One possible modification concerns models of so-called inhomogeneous nucleosynthesis.

The idea is that in the very early universe (the first microsecond) the subnuclear particles that later made up the protons and neutrons existed in a free state as a quark-gluon the universe expanded and cooled, this quark-gluon plasma would.

Apr 16,  · The term nucleosynthesis refers to the formation of heavier elements, atomic nuclei with many protons and neutrons, from the fusion of lighter elements. The Big Bang theory predicts that the early universe was a very hot place. One second after the Big Bang, the temperature of the universe was.

To decide that question we need more information, and one of the strongest pieces of evidence that the dark matter is exotic is Big Bang nucleosynthesis (BBN). The . The authors of this volume have been intimately connected with the conception of the Big Bang model since Following the late George Gamow's ideas in and more particularly in that the early universe was an appropriate site for the synthesis of the elements, they became deeply involved in the question of cosmic nucleosynthesis and particularly the synthesis of the light elements.

Nucleosynthesis – The Physics Hypertextbook