So the elements in our universe are getting more and more heavy.
   I think you're right: the Universe itself just MIGHT eventually
   end up being mostly IRON (since that is the most stable element
   in the universe). I've NEVER heard a theory that says that
   before - i would love to -- but i suspect you'e right - there
   will eventually be less and less hydrogen + helium as each star
   explodes which means fewer and fewer stars are born, leading up
   to a smaller, cold and rusty universe. "