16: The Early Universe
- Page ID
- 30493
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Chapter 16 travels back in time to the earliest moments of the Universe. The chapter starts with the formation of the lightest chemical elements, and continues back to the extreme temperatures and densities at which the first subatomic particles formed. The last sections of the chapter discuss cosmic inflation and the limits of our knowledge at the very start of the Universe’s existence.
- 16.1: The Formation of the Lightest Elements
- You will know the overall abundances of the elements. You will know how we measure abundances (especially of the lightest elements). You will be able to determine which abundances are primordial. You will be able to explain how the neutron to proton ratio = 1/7 causes basic proportions of ¾ H and ¼ He. You will understand the effect of baryon-to-photon ratio on the abundances of the light elements. You will know that the measured abundances of the light elements can all be explained by ig Bang N
- 16.2: Particle Soup
- You will know the fundamental particles. You will know the fundamental forces. You will be able to calculate the ambient temperature corresponding to the mass-energy of particle reactions. You will know that at different temperatures, the Universe undergoes various transitions: electroweak transition, quark confinement, proton-antiproton annihilation, neutrino decoupling, and electron-positron annihilation. You will know that the electromagnetic, weak, and strong forces were once unified.
- 16.3: Inflation
- You will know that magnets are never seen as single poles and that and explanation for this led to a theory with cosmological implications. You will know that the Universe underwent a period of rapid, exponential expansion at early times. You will understand how inflation can explain the observed homogeneity and isotropy of the Universe. You will understand how inflation can explain the observed flat geometry of the Universe. You will know that inflation is driven by a release of energy from the
- 16.4: The Beginning
- You will know that the early Universe was extremely dense and that changes happened rapidly. You will know that the Planck time is the earliest era we can probe. You will know that at the Planck time all four forces are thought to be unified. You will know that all of space and time were created in the beginning.
- 16.5: Wrapping It Up 16 - Timeline of the Early Universe
- You will use a timeline to pull together their understanding of conditions and transitions in the early Universe. Transitions occur due to temperature, which corresponds to energy, and which decreases over time.
Thumbnail: Artist's interpretation of the Big Bang, with representations of the early universe and its expansion. (Public Domain; NASA's Goddard Space Flight Center/CI Lab)