Birth of the Universe

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University of Massachusetts Amherst
Alexandra Pope

The Birth of the Universe What were conditions like in the early universe? ● The universe is expanding. ● The early universe must have been extremely hot and dense. How were particles created? ● Photons converted into particle-antiparticle pairs and vice versa. ● E = mc^2 ● The early universe was full of particles and radiation because of its high temperature. Four Known Forces in the Universe: ● Strong force - holds nuclei together. ● Electromagnetism - holds atoms and molecules together. ● Weak force - important for fusion/fission, affects neutrinos. ● Gravity * Forces begin to unify at high temperatures. How did the early universe change with time? Planck Era ● First era after the Big Bang ● Before Planck time (~10^-43 second) ● No theory to explain the Universe during this time. GUT Era ● GUT: Grand Unified Theory ● Strong, Weak, and EM operated as a single force. ● Lasts from Planck time (~10^-43 sec) to end of GUT force (~10^-38 sec). Electroweak Era ● Strong force separates: 3 forces ● Lasts from end of GUT force (~10^-38) to end of electroweak force () Particle Era ● 4 distinct forces ● Number of particles ~ number of photons ● Amounts of matter and antimatter nearly equal (roughly 1 extra proton for every 10^9 proton - antiproton pairs) Era of Nucleosynthesis ● Begins when matter annihilates remaining antimatter at ~0.001 second. ● Nuclei begin to fuse. Era of Nuclei ● Helium nuclei form at age ~ 5 minutes. ● Universe became too cool to blast helium apart. ● Sets the amount of Helium we see today - 25% helium. Era of Atoms ● Atoms form at age ~ 380,000 years ● Temperature of Universe ~ 3,000 K ● Cosmic microwave Background (CMB) radiation released. Era of Galaxies ● Galaxies form at age ~ 1 billion years REVIEW Primary Evidence for the Big Bang Theory ● We have detected the leftover radiation from the Big Bang (specifically CMB radiation). ● The Big Band theory correctly predicts the abundance of helium and other light elements. 1. How do these observations of CMB support the Big Bang theory? ● The cosmic microwave background - the radiation left over from the Big Bang - was detected by Penzias and Wilso
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