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Very early universe

The Big Bang
Early Universe
Life and Death of Stars
Galaxy Formation
The Solar System
Exotic objects
End of the Universe
Who created the universe?
What is Time?
Life beyond Earth
NASA Missions
Particle Map
Glossary
Sources
Planck time (up to 10^–43 seconds after the big bang)
Almost nothing is known about this period of the very early universe. Even the most advanced particle accelerator is incapable of producing a temperature high enough to recreate the conditions of the very early universe, preventing scientists from making any meaningful laboratory observations of this extremely brief time period. One Planck time is the time it would take a photon travelling at the speed of light to cross a distance equal to one Planck length, which is 10 ^-43 of a second, the smallest time measurement that is possible. One Planck length is a spatial dimension so small that it can not be physically measured. The Planck epoch is the time interval starting at the instant of the big bang and ending one planck time (10 ^-43 seconds) later. During this amazingly brief interval, the inflating universe was so hot that the four fundamental forces of today's physical universe (gravity, electromagnetism, the weak nuclear force and the strong nuclear force) were unified as one superforce and it was too hot for any sub-atomic particles to exist.

Grand unification (10^–43 seconds to 10^–36 seconds after the Big Bang)
As the universe expands and cools from the Planck epoch, gravitation begins to separate from the unified four fundamental forces. The unification of forces is broken as the strong nuclear force separates from the electroweak force. This occurs as soon as inflation does.

Electroweak unification (10^–36 seconds to 10^–12 seconds after the Big Bang)
During this interval, the universe has cooled adequately for the nuclear strong force to become independent of the electro-weak force, and a period of exponential inflation of the universe begins.

Inflationary expansion (10^–36 seconds to 10^–32 seconds after the Big Bang)
Inflation is characterized by a flat, homogeneous universe (its curvature reaches the asymptotic value) and the universe rapidly expands. During this extremely brief interval, inflation caused expansion by a factor of around 10^50. The idea of an expansion by a factor of 100 trillion trillion trillion trillion during a time of only 100 trillionths of a trillionth of a trillionth of a second is impossible to conceive.

Quark epoch (10^–12 seconds to 10^–6 seconds after the Big Bang)
At the end of the electroweak epoch, all the fundamental particles are believed to have acquired their mass via the Higgs boson. The fundamental interactions of gravitation, electromagnetism, the strong interaction and the weak interaction are now independent of one another, but the temperature of the universe is still too high to allow quarks to bind together to form larger particles.

Hadron formation (10^–6 seconds to 1 second after the Big Bang)
The quark-gluon plasma that composes the universe cools until hadrons, including baryons such as protons and neutrons, can form. At approximately 1 second after the Big Bang neutrinos decouple and begin traveling freely through space. This cosmic neutrino background, while unlikely to ever be observed in detail, is analogous to the cosmic microwave background that was emitted much later. At the end of the hadron epoch, the majority of hadron / antihadron pairs annhilated themselves.

Lepton epoch
The lepton epoch began about 1 second after the big bang, during which the mass of the universe was dominated by leptons. At the end of the lepton epoch, the majority of lepton / antilepton pairs annhilated themselves.

Photon epoch
During the photon epoch, the mass of the universe was dominated by photons.

Nucleosynthesis (3 minutes to 20 minutes after the Big Bang)
The creation of new atomic nucleii from already existing nucleons (protons and neutrons) that were formed, in turn from the quark-gluon plasma dominating the very early universe, when the temperature of the universe cooled below 2 trillion degrees. The atoms that arose from these nucleons were all of the atoms that ever were or ever will be. They are the same atoms we are made of today and are breathing now.

Matter domination: 70,000 years
At this stage, cold dark matter dominates, paving the way for gravitational collapse to amplify the tiny asymmetries left by cosmic inflation, making dense regions denser and rarefied regions more rarefied.

Recombination: ca 377,000 years
This indicates the release of the Cosmic Microwave Background. As the density of the universe falls, hydrogen and helium nucleii begin to form as positive ions, since no electrons are bound to the nucleii. As the temperature cools, free electrons are bound to the ions forming neutral atoms. Because most of the free protons in the universe are now bound up in atoms, photons are now able to travel freely, releasing the radiation that we can still see today as the CMB. The CMB is today a picture of the universe at the end of this epoch (377,000 years after the Big Bang.

Dark age
Before decoupling occurs most of the photons in the universe are interacting with electrons and protons in the photon–baryon fluid. The universe is opaque or "foggy" as a result. There is light but not light we could observe through telescopes. The baryonic matter in the universe consisted of ionized plasma, and it only became neutral when it gained free electrons during "recombination," thereby releasing the photons creating the CMB. When the photons were released the universe became transparent.