Water and Life

• liquid H2O is believed to be essential for life as we know it
  • H2O is a “universal solvent” which promotes the complex chemistry necessary to grow ever-larger organic molecules
  • Earth’s life started in our liquid H2O oceans
  • many living organisms are mostly liquid H2O
• we believe liquid H2O is a necessary, but not sufficient, condition for life to arise
  • require, also, an energy source
    • High quality energy must be expended to create complex lifeforms out of simple molecules (the Second Law of Thermodynamics)
  • also, need other chemical elements
    • Earth life requires also C, N, P, etc.
  • Mars has the other ingredients for life
    • plenty of chemicals
    • energy from Sunlight or “geothermal” vents

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