Notes on the Origin of the Universe

Overview

• The universe encompasses everything: particles, galaxies, space, time, and life.
• The origin of the universe is key to understanding everything else.
• Various scientific theories and creation myths attempt to explain its genesis, with the Big Bang theory being the most accepted.

The Big Bang Theory

• The universe began as a hot, infinitely dense point, similar to a supercharged black hole, around 13.7 billion years ago.
• The explosion created all matter, energy, space, and time.

Stages of the Universe's Evolution

1. Radiation Era

   • Dominated by radiation after the Big Bang.
   • Composed of smaller stages called epochs:
     • Planck Epoch: Only energy existed; the superforce was present.
     • Gravity split from the superforce at the end of this stage.
     • Grand Unification Epoch: Three forces remained unified until strong nuclear force broke away.
     • Inflationary Epoch: Rapid expansion from atomic size to grapefruit size.
     • Electroweak Epoch: Electromagnetic and weak forces split.
     • Quark Epoch: Universe too hot to form subatomic particles.
     • Hadron Epoch: Cooling allowed quarks to form protons and neutrons.
     • Lepton and Nuclear Epochs: Protons and neutrons fused to create helium.

2. Matter Era

   • Defined by the predominance of matter in the universe.
   • Spans billions of years, including present day.
   • Comprises three epochs:
     • Atomic Epoch: Universe cooled; electrons attached to nuclei (recombination), forming hydrogen.
     • Galactic Epoch: Atomic clouds formed galaxies; clusters of atoms began to collect.
     • Stellar Epoch: Stars formed within galaxies, converting helium and hydrogen into other elements, shaping the universe.

Importance of Stellar Epoch

• Stars created the building blocks for planets, moons, and life.
• Ecosystem of the universe formed through various developmental stages.

Conclusion

• Many questions about the universe's origins remain, but answers may emerge over time.