courses:ast100:1
Table of Contents
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1. Particle Age
| Time | Event | Details |
|---|---|---|
| $0$ | The Big Bang | The singularity event marking the origin of space, time, energy and matter (STEM). The universe emerges as an unimaginably hot and dense “primeval fireball”. |
| $10^{-35}$ to $10^{-32}$ seconds | Cosmic Inflation | A brief, exponential expansion where the universe swells in size by a factor of roughly $10^{50}$. This process smoothed out initial irregularities. |
| $10^{-43}$ to $10^{-10}$ seconds | Separation of Forces | As the universe cooled, the single unified “superforce” separated into the four fundamental forces (energies) of nature: gravity, the strong nuclear force, the weak nuclear force, and electromagnetism. |
| $10^{-35}$ to 1 second | Particle Creation & Annihilation | Energy converted into matter via “pair production”. Quarks and leptons (e.g., electrons) emerged. Matter and antimatter collided and annihilated, leaving a slight excess of ordinary matter. |
| 3 minutes to 15 minutes | Primordial Nucleosynthesis | The universe cooled sufficiently (below $10^9$ K) for protons and neutrons to fuse. This “Nuclear Epoch” produced the first atomic nuclei: heavy hydrogen (deuterium), helium, and trace amounts of lithium. |
| 50,000 years | Matter Domination | The “crossover point” where the energy density of matter finally exceeded that of radiation (or energy). This marked the end of the “Radiation Era” and the beginning of the “Matter Era,” setting the stage for structure formation. |
| 300,000 to 380,000 years | Recombination & Decoupling | Electrons combined with nuclei to form neutral atoms (recombination). This neutralized the charged fog, allowing photons to travel freely (decoupling), observable today as the Cosmic Microwave Background (CMB). |
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