Timeline of the Universe After the Big Bang

10^-35 seconds / Inflation Era

• The universe begins as an incredibly small, dense, and hot point of energy.

• Rapid exponential expansion (inflation) occurs, causing the universe to grow from subatomic size to about the size of a football in a fraction of a second.

• Quantum fluctuations during this period lay the foundation for the large-scale structure of the universe.

10^-32 seconds / Quark Era

• Energy condenses to form fundamental particles like quarks and gluons.

• Quarks and antiquarks annihilate each other, but a slight asymmetry (matter-antimatter imbalance) allows matter to dominate, leaving behind a small excess of quarks.

10^-9 seconds / Electroweak Era

• The four fundamental forces (gravity, electromagnetism, strong nuclear force, and weak nuclear force) begin to separate as the universe cools.

• Natural laws, including gravity, start to take shape.

10^-5 seconds / Hadron Era

• Quarks combine to form protons and neutrons (collectively called hadrons).

• The universe is still extremely hot and dense, with particles constantly colliding and interacting.

1 second / Nucleosynthesis Begins

• The universe cools enough for neutrons to decay into protons or combine with protons to form the first atomic nuclei (primarily hydrogen and some helium).

• This marks the beginning of Big Bang nucleosynthesis, creating the lightest elements.

200 seconds / Opaque Universe

• The universe continues to cool, allowing protons and electrons to combine and form neutral hydrogen atoms.

• The dense fog of hydrogen atoms scatters light, making the universe opaque to visible light.

300,000 years / Recombination and Cosmic Microwave Background (CMB)

• The temperature drops further, enabling electrons to bind to nuclei, forming stable atoms (recombination).

• Photons are no longer scattered, and the universe becomes transparent.

• The release of these photons creates the Cosmic Microwave Background (CMB), a snapshot of the early universe.