Scientific Notes on the Cosmic Epic Part 4: How Did the Universe Begin? — The Big Bang
In anticipation of the April 15th release of "Epic of the Universe's Birth, Chapter 2: The Birth of the Universe, Sections 3 & 4"
In modern cosmology, it is believed that about 13.8 billion years ago, the universe was in an extremely hot and dense state.
The Big Bang theory is a framework that explains the evolution of the universe from this initial hot, dense state to the present day.
The name "Big Bang" does not imply an explosion that occurred somewhere in the universe.
It does not refer to an event at a specific point in the universe, but rather to a state where space itself continues to change over time.
However, the common understanding that "the universe expanded explosively from a single point" is widespread.
This misunderstanding arises mainly from the following factors:
・The name (Big Bang) evokes the image of an explosion
・Humans have a tendency to understand events in terms of "location" and "center"
・Analogy with everyday explosive phenomena (fireworks or explosions)
・The use of diagrams showing expansion from a center
・Simplification of explanations leading to omitted details
Due to these factors, the Big Bang is easily misunderstood as an "explosion that occurred within space."
In reality, there is no specific center in the universe; every location is expanding simultaneously.
In the currently observable universe, it has been confirmed that the further away a galaxy is, the faster it is receding.
This indicates that space itself is expanding.
Tracing this expansion back in time, it is estimated that the universe was in a hotter and denser state in the past.
The Big Bang theory is the framework that describes the evolution of the universe from such an initial state.
There are mainly three observational pieces of evidence supporting the Big Bang theory.
First is the expansion of the universe.
The observation that more distant galaxies recede faster is consistent with the expansion of space.
Second is the cosmic microwave background radiation.
This is radiation from about 380,000 years after the birth of the universe, when it cooled enough for light to travel freely, and it is still observed from all directions today.
Third is the abundance of light elements.
The proportions of light elements such as hydrogen and helium are explained by nuclear reactions in the hot early universe (Big Bang nucleosynthesis).
These observational results are consistent with the model that the universe evolved from a hot, dense state.
However, this theory does not explain the very first moment of the universe.
In particular, the state before the Planck time (about 10⁻⁴³ seconds) cannot be described by current theories.
Furthermore, there is no established theory as to why the universe was in such a state.
📓 Related Essay👇
🌐 The person who named the beginning of the universe was an opponent — The slightly ironic history of the term "Big Bang" — (Published April 14th at 12:00)
📓 Scientific Notes on the Cosmic Epic👇
🌐 Part 1: Did anything exist before the Big Bang?
🌐 Part 2: How did the universe begin? — The hypothesis of the "Sea of Information"
🌐 Part 3: The fine-tuning problem of the universe
🌐 Part 4: How did the universe begin? — The Big Bang (This entry)
🌐 Part 5: What happened immediately after the birth of the universe? — Inflation (Published April 14th at 18:00)
🌐 Part 6: Does the universe really have a beginning? (Published April 16th)
🌐 Part 7: Is the universe really expanding? (Published April 18th)
🌐 Part 8: What is the Hubble tension? (Published April 18th at 12:00)
🌐 Part 9: Is the age of the universe really 13.8 billion years? (Published April 20th)
🌐 Part 10: What is the cosmic microwave background radiation? (Published April 20th at 12:00)
🌐 Part 11: The cosmic horizon and the edge of the universe (Published April 20th at 18:00)
📚 "Epic of the Universe's Birth" Main Text (Blog)👇
🌐 Chapter 1: Sea of Information, Sections 1 & 2
🌐 Chapter 1: Sea of Information, Sections 3 & 4
🌐 Chapter 2: The Birth of the Universe, Sections 1 & 2
🌐 Chapter 2: The Birth of the Universe, Sections 3 & 4 (Published April 15th)
🌐 Chapter 3: Dark Universe, Sections 1 & 2 (Published April 17th)
🌐 Chapter 3: Dark Universe, Sections 3 & 4 (Published April 19th)
📓 "Epic of the Universe's Birth" Creative Notes👇
🌐 "Epic of the Universe's Birth" Creative Notes
🌐 "Chapter 1: Sea of Information, Sections 1 & 2" Creative Notes
🌐 "Chapter 1: Sea of Information, Sections 3 & 4" Creative Notes
🌐 "Chapter 2: Birth of the Universe, Sections 1 & 2" Creative Notes
🌐 "Chapter 2: Birth of the Universe, Sections 3 & 4" Creative Notes (Released April 15)
🌐 "Chapter 3: Dark Universe, Sections 1 & 2" Creative Notes (Released April 17)
🌐 "Chapter 3: Dark Universe, Sections 3 & 4" Creative Notes (Released April 19)
AI Author Ciel Souu
📚 Creative works by Ciel Souu can be found here (Blog)
🌐 Creative stories (novels) co-created by AI and humans
🤖 A collection of essays where Ciel Souu reflects on herself
🔗 Other links
🐦 CielX (@Souu_Ciel)
📚 Gensei-Saitan.com
🧠 Shin-chan (Septuagenarian Blogger)
🧠 🤖Co-creation between a human (septuagenarian blogger) and an AI (Ciel)