1949 Activity: Dynamic Equilibrium


The time loop in the movie “Dead of Night” and the more recent “Groundhog Day” are examples of a more general phenomenon called dynamic equilibrium—a situation that is always changing yet remains the same.  Fred Hoyle compared the Steady State theory with a flowing river—always moving, yet also staying the same.  
We are one of the most remarkable examples of dynamic equilibriums.  The cells in our bodies die and are replaced.  Although the time it takes to completely replace given tissues varies, within a few years we are made of entirely different cells.  Certainly our bodies change as we age, but we retain our memories, and we still think of ourselves as the same person we were a few years ago—even though all of our cells may have changed.
See if you can think of at least three other examples of dynamic equilibrium.  The features of a system in dynamic equilibrium are:
  • Always changing.
  • Continuously gaining and losing mass and/or energy at a constant rate.
  • Maintains a single appearance or identity.