Things Fall Apart or Entropy 101

I often tickle my students imaginations by asking them how we'd know if there had been an advanced civilization say, 50 thousand years or so ago.  Their first answer is usually, "By the stuff they leave behind."  I counter with, "Probably not."

Covering 500 years in your neighborhood, this two minute animated video from The Long Now Foundation, of which I am a member, illustrates the point well.