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Chapter 22

Chapter 22: Structure in the Universe

Study Plan

The universe that emerged from the Big Bang was incredibly uniform, wholly unlike today's universe of galaxies, stars, and planets. As our journey nears its end, we tackle face-on the question that has been with us all along: Where does structure in the universe come from? Here we find that complex structure is a natural, unavoidable consequence of the action of physical law in an evolving universe:

  • Just as stars cluster together in galaxies, galaxies gather together to form large and small clusters of galaxies, which themselves cluster together into giant superclusters.
  • Galaxies formed as slight ripples in the dark matter emerging from the Big Bang, which then collapsed under the force of gravity, pulling in normal matter as well.
  • Larger galaxies form from the merging together of small protogalaxies.
  • Galaxies were drawn together by gravity to form the large groupings of galaxies we see today.
  • There are two types of dark matter: cold and hot.
  • Our own observable universe may be but one among an infinite collection of universes.
  • Our current understanding of physics suggests that over the long course of time, our universe will grow very cold and structure itself may slowly disappear.

Organize

  • Read Chapter 22 in your textbook or ebook.
  • Take the Diagnostic Quiz to assess your understanding of the basic concepts and identify gaps in your understanding of the assigned reading.

Learn

  • Use the FlashCards to test your memory for new terms.
  • Work the "Thinking about the Concepts" and "Applying the Concepts" questions in the end of chapter review materials.
  • If your instructor has assigned SmartWork online homework, login from the right navigation pane for additional practice and review.

Connect

  • Read Connections 22.1, Parallels between Galaxy and Star Formation, and the Seeing the Forest through the Trees section at the chapter's end to draw your attention to recurring themes and help prepare you for concepts explored more fully in the other chapters.
  • Visit Astronomy in the News for breaking news of new discoveries and the opportunity to apply what you've learned in this chapter to real-world (and real Universe) events.
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