Life in the Universe

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Life in the Universe

• 5 December 2014

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Are we alone?

• Life arose quickly on Earth, around 4 billion
  years ago
• Star formation makes planets, too they should be
  comon
• Impacts can frustrate life, but it recovers
• Extreme life forms like it hot and may have
  arisen first on ocean bottoms
• Moons also have heat sources

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Urey-Miller Experiment
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The Drake Equation
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Summary

• Life is a chemical process that includes
  metabolism, growth and reproduction.
• All life on earth evolves
• The 3 requirements for life biogenic elements
  (SPONCH), water and energy
• Earth life is based on carbon and requires liquid
  water
• The range of distance where a planet can have
  liquid water on its surface is the habitable
  zone

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More Summary

• Large impacts can destroy life forms or even
  sterilize the planet. Jupiter protects Earth from
  asteroid impacts. Life changes the planet
• All Earth life is related, sharing the same DNA.
  It likely arose from a single ancestor
• If other planets are like Earth, life could be
  common. Meteorites can transfer life.
• The Drake equation calculates the number of
  technical civilizations we might communicate with