## Friday, December 20, 2013

### The Last Question

Entropy and its role in the Second Law of Thermodynamics is one of the fundamental ideas of all science. One can think of entropy roughly as a measure of the disorder within a system. An interesting feature of entropy is that it is not conserved. Rather, it tends to increase over time (the system becomes more disordered). In the 4th edition of Intermediate Physics for Medicine and Biology, Russ Hobbie and I write
…under what conditions can the entropy of a system be made to decrease?

The answer is that the entropy of a system can be made to decrease if, and only if, it is in contact with one or more auxiliary systems that experience at least a compensating increase in entropy. Then the total entropy remains the same or increases. This is one form of the second law of thermodynamics. For a fascinating discussion of the second law, see Atkins (1994).
 Nine Tomorrows, A short story collection by Isaac Asimov containing “The Last Question.”
The reference is to P. W. Atkins’ 1994 Scientific American book The 2nd Law: Energy, Chaos and Form. It is a great book written for a layman with little or no mathematics that clearly conveys the insights provided by the second law.

The very first course I ever taught, at Vanderbilt University in the fall of 1995, was an undergraduate thermodynamics class. When we talked about entropy, I had all my students read the short story “The Last Question” by Isaac Asimov. This marvelous tale speculates about what will happen to the universe as entropy slowly but steadily increases. Regular readers of this blog know that I am a big Asimov fan (for instance, see here), and The Last Question is one of his best stories. That is not just my opinion. Asimov himself said it was his favorite short story of all he had written. You can read it here, or listen to the Good Doctor himself read it below.

 I Robot, by Isaac Asimov.
For those wanting more Asimov short stories, I recommend “Nightfall”and “The Ugly Little Boy.” Also I, Robot is a collection of loosely related short stories based on the three laws of robotics (please, skip the 2004 film by the same name featuring Will Smith). One big Asimov fan posted reviews of all Asimov’s books. Enjoy.

Finally, let me share one more crucially important point. Amazon.com says you still have time to order IPMB and have it delivered by Christmas. If you plan on putting a copy of IPMB in each of your loved one's stockings (and who doesn’t?), you had better order soon!

1. Asked Santa to bring IPMB Matlab routines for me and my boys' stockings.

With hopes an on-line course will dance through Brad's head.

Merry Christmas. We appreciate you.

E Franck

2. On online course, including subroutines in Matlab - GENIUS! Do It, Do It, Do It!

3. I say that respectfully, of course! I certainly appreciate you, too!