Big Bang Timeline

From 0 to approximately 10-43 seconds

Planck Epoch

This is the closest that current physics can get to the absolute beginning of time, and very little is known about it. At this point, the universe possesses a temperature of approximately 1032°C (1 Planck Temperature) and a length of only 10-35 meters (1 Planck Length).

From 10–43 seconds to 10–36 seconds

Grand Unification Epoch

The first elementary particles (and antiparticles) start to form and the force of gravity separates from the other fundamental forces.

From 10–36 seconds to 10–32 seconds

Inflationary Epoch

The universe underwent an extremely rapid exponential expansion which is known as cosmic inflation. The linear dimensions of the early universe increased during this period.

From 10–36 seconds to 10–12 seconds

Electroweak Epoch

During this period, particle interactions create large numbers of exotic particles, including W and Z bosons and Higgs bosons.

From 10–12 seconds to 10–6 seconds

Quark Epoch

In this time, quarks, electrons and neutrinos form in large numbers as the universe cools off to below 10 quadrillion degrees. The four fundamental forces assume their present forms while quarks and antiquarks annihilate each other upon contact. In a process known as baryogenesis, a surplus of quarks survives, which will combine to form matter.

From 10–6 seconds to 1 second

Hadron Epoch

The temperature of the universe cooled to around a trillion degrees which was cool enough to allow quarks to combine to form hadrons. Electrons collided with protons to form neutrons and give off massless neutrinos. Some neutrons and neutrinos re-combine into new proton-electron pairs

From 1 second to 3 minutes

Lepton Epoch

After the majority of hadrons and antihadrons annihilate each other, leptons and antileptons dominate the mass of the universe. As electrons and positrons collide and annihilate each other, energy in the form of photons is created which results in colliding photons creating more electron-positron pairs.

From 3 minutes to 20 minutes

Nucleosy-nthesis

The temperature of the universe falls to about a billion degrees where atomic nuclei can begin to form. Protons and neutrons combine through nuclear fusion to form the nuclei of hydrogen, helium and lithium.

From 3 minutes to 240,000 years

Photon Epoch

During this long time period of gradual cooling, the universe was filled with plasma which is a hot, opaque soup of atomic nuclei and electrons. Considering 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 photons. These continue to interact often with the charged protons, electrons and nuclei.

From 240,000 to 300,000 years

Recomb-

ination/Decoupling

While the temperature of the universe falls to around 3,000 degrees its density also continues to fall. Ionized hydrogen and helium atoms capture electrons, this neutralizes their electric charge. By the end of this period, the universe consists of a fog containing about 75% hydrogen and 25% helium, with small traces of lithium.

From 300,000 to 150 million years

Dark

Age

This is the period after the formation of the first atoms and before the first stars. The universe at this time is literally dark, with no stars to give off light. During this time, activity in the universe has tailed off dramatically because of very low energy levels and very large time scales.

From 150 million to 1 billion years

Reioniza-

tion

In this period, the first quasars form from gravitational collapse and the high radiation they emit reionizes the surrounding universe. From this point on, most of the universe goes back to being composed of ionized plasma.

From 300 - 500 million years onwards

Star and Galaxy Formation

Gravity amplifies small irregularities in the density of the primordial gas. Pockets of gas increase in density, even as the universe continues to expand rapidly. These small, dense clouds of cosmic gas begin to collapse beneath their own gravity, becoming hot enough to spark nuclear fusion reactions between hydrogen atoms This created the very first stars. The first stars are short-lived but eventually other stars begin to form from the material left over from previous rounds of star-making. Large volumes of matter collapse to form galaxies.

From 8.5 - 9 billion years

Solar System Formation

The Sun is a late-generation star, incorporating the debris from many generations of earlier stars. The sun and the Solar System around it formed roughly 4.5 to 5 billion years ago

13.7 billion years since the beginning

The expansion of the universe and recycling of star materials to create new stars continues.

Today