The early universe

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Space, time & radiation all created in Big Bang
1. At first universe was hot glowing ball of radiation & matter, temperature fell as it expanded
  1. universe now cold + dark (besides stars)
    1. Stars we see at night in the Milky way galaxy - our home galaxy
      1. Galaxy is a collection of billions of stars held together by their own gravity
      2. Light from furthest galaxies taken billions of years to reach us - powerful telescopes give picture of universe long ago
Before galaxies + stars formed, universe was dark patchy cloud of hydrogen & helium
1. Dark age of the Universe
Force of gravity pulled matter into galaxies and stars
1. Uncharged atoms don't repel each other but they can attract each other
  1. During dark age of universe, force of gravitational attraction was at work without any opposition from repulsive forces
  2. Gravity between 2 helium nuclei unable to pull them together as they are both positively charged
    1. force of repulsion much greater than force of gravity between them
2. As universe continued to expand, became more patch as denser parts attracted nearby matter
  1. Gravity pulled more matter into denser parts, turned them into gigantic clumps which eventually turned into galaxies and stars by force of gravity

Resource summary

	Created by r.andom about 11 years ago