Editing Cosmology and the Big Bang (section)

== <span style="color: #FFFFFF;">Understanding</span> ==
The history of the universe is a story of **Cooling and Complexity**.

**1. The Timeline of Everything**:
* **The Planck Epoch** ($10^{-43}$ sec): We don't know what happened here; physics breaks down.
* **Inflation**: The universe grows from the size of an atom to the size of a galaxy in a trillionth of a trillionth of a second.
* **Nucleosynthesis** (3 mins): The universe is cool enough for the first protons and neutrons to form.
* **Recombination** (380,000 years): The universe becomes transparent; light can finally travel. This is the source of the **CMB**.
* **The Dark Ages**: No stars yet; just a fog of gas.
* **Reionization**: The first stars and galaxies form, lighting up the cosmos.

**2. The Evidence**:
* **Hubble's Law**: We see galaxies moving away. If we "rewind" the film, they all meet at one point.
* **The CMB**: We can see the "baby photo" of the universe in every direction using radio telescopes.
* **Light Elements**: The math of the Big Bang predicts exactly how much Hydrogen and Helium should exist, and that matches what we see in the stars.

**3. The Composition**:
The universe is only 5% "Normal Matter" (atoms). The rest is 27% **Dark Matter** and 68% **Dark Energy**. We are the 5% that can see the rest.
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