Match the events related to the formation of the universe with the stages during which they occurred:
1. The universe was at its densest.
- Event: Big Bang
- Explanation: The Big Bang is believed to be the initial moment of the universe when all matter and energy were concentrated in an extremely dense and hot state.
2. Gravity came into existence.
- Event: Shortly after the Big Bang
- Explanation: After the Big Bang, as the universe expanded and cooled, the fundamental forces of nature, including gravity, began to differentiate and exert their influence.
3. The universe became transparent.
- Event: Reionization Era
- Explanation: After the initial phase of the universe, which was opaque due to the high energy radiation, the universe cooled down, allowing the formation of neutral atoms. During the reionization era, about 380,000 to 150 million years after the Big Bang, the universe became transparent as electrons and protons combined to form neutral hydrogen, allowing light to travel freely through space.