Summary

• The 2nd law explains basic phenomena

  • The tendency for mechanical energy to be lost to heat
  • The direction of time – irreversible
  • Maximum efficiency of heat engines – NO exceptions!

• The 2nd law is one of the most disturbing laws of physics

  • The universe must wind down
  • “Thermal death”
  • Conversely, it cannot have existed forever it is present form – there must have been a beginning

• Explained by probabilities and the motions of extremely large numbers of atoms in an ordinary piece of matter ~ 1021 – 1026

  • Boltzmann
  • Leads up to many ideas in modern physics - later

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