The Birth of the Universe
The Big Bang Theory
- Everything began as a hot and dense collection of matter and radiation
- It was so hot that photons could transform themselves into matter and vice versa. 𝐸 =
𝐸𝐸 . There were reactions that created and annihilated particles
- The universe cools as it expands
- There are 4 forces:
- Electromagnetic Force - depends on electrical charge of particle rather than mass.
Responsible for all chemical and biological reactions.
- The Strong Force - operates on extremely short distances. Binds protons and
neutrons in atomic nuclei.
- The Weak Force - operates on extremely short distances. Plays role in nuclear
reactions like fusion and fission. Only force besides gravity that affects weakly
interacting particles like neutrinos.
- In early universe, the forces were not as distinct as they are today. They merge.
Ex: Electroweak force, electroweak + strong force = the GUT force, or possibly
all the forces could’ve combined into one “super force”
- Eras of the early universe
- The Planck Era
- Times before the universe was 10 −43 second old - Substantial energy fluctuations
- We don’t have a theory to describe conditions in this era.
- The GUT Era
- Merger of strong, weak, and electromagnetic force at temps above10 K. 29
- Ended when GUT split into strong and electroweak forces when universe
was 10 −38second old.
- Inflation, a sudden and dramatic expansion of universe, happened
- The Electroweak Era
- Three forces now: gravity, strong, electroweak
- Temp dropped to 10 K, electromagnetic and weak forces separated
- We have experimental data concerning the conditions in the universe at
the end of this era, not from any time before it.
- The Particle Era
- The time between the end of the electroweak era and the moment when
spontaneous particle production ceased.
- Photons turned into particles that we no longer find in the universe today,
- Ended when the universe reached 1 millisecond and temp was at 10 K, it 12
wasn’t hot enough to produce protons and antiprotons spontaneously.
Protons must have slightly outnumbered antiprotons at the end of this era.
- The Era of Nucleosynthesis
- Protons and neutrons left over began fusing into heavier nuclei, but
gamma rays blasted them apart as fast as they formed.