## fredag 10 juli 2009

### Teaching the Second Law of Thermodynamics

Listening to the MIT World Distributed Intelligence panel debate on Teaching the Second Law, we hear the moderator Robert J. Silbey setting the platform:
• I have taught thermodynamics for 40 years at MIT and I must say that whenever we get to the Second Law, I always am very nervous. Toscanini always said to the orchestra when conducting Beethoven's 9th Symphony: Courage, have courage! It's the same with the Second Law.
Teaching a subject which is not understood by the teacher, is of course difficult, and makes the teacher nervous and the student unsatisfied.

To all nervous teachers and unhappy students we have a good message: Entropy as a thermodynamic concept is not needed and thus does neither have to be understood nor be taught. The Second Law can be expressed in terms of heat, potential and kinetic energies, without reference to entropy! This is explained in the knol The Second Law of Thermodynamics and the related The Direction of Time. Compare with the confusing messages of the MIT panel:

Joseph Smith:
• What is entropy and why is it neeed?
• Entropy measures the degradation of energy.
• Entropy is not really needed when energy is separated into heat energy and other energies...
• Need to define the idealizations of isolation, equilibrium and boundaries...
• If we don’t get those straight in the beginning student’s mind, then there’s a lot of confusion.
• The teaching approach depends on the application, and applications are both theoretical and practical.
Howard Butler:
• Teaching the Second Law is much more difficult and challenging a task than teaching Newton’s Second Law of Motion, both because the concepts involved are so much more complex and abstract, and because the Second Law takes on very different forms depending on which thermodynamic domain is being considered.
Andrew Foley:
• The whole concept as is an accounting problem with money being moved through a mint. We can shove the property of energy instead of money, and produce a form of accounting for energy equations. First Law, Second Law -- it’s all accounting.
Kim Hamad- Schifferli:
• Entropy is very difficult for students to grasp viscerally, and that one thing that helps greatly is the lattice model -- the entropy of mixing two gases, for example.
Bernhardt Trout:
• We owe it to our students to teach them about these most fundamental issues to try to reengage the original questions in the original context in which they existed.
Jeffery Lewin:
• In the great book, Professor Keenan uses the energy-entropy volume space quite late to discuss equilibrium. More can be made of this space in teaching.
Enzo Zanchini:
• A rigorous definition of entropy valid also for nonequilibrium states is needed.
Michael von Spakovsky:
• There are so many textbooks on thermodynamics, so many schools of thought.
• There is not a whole lot of agreement on a lot of things.
• I propose a broader, self-consistent quantum kinematics and dynamics, where entropy becomes an intrinsic property of matter, including single particles.
What do you get out of this, but confusion? If you need more confusion, listen to Foundations of the Second LawThe Second Law and Quantum PhysicsThe Second Law and Statistical Mechanics and The Second Law and Cosmology as an expression of Distributed Intelligence:
• Bedeaux: There is as yet no fully satisfactory derivation of the Second Law, in non-equilibrium statistical mechanics.
• Tegmark: Why is entropy so low? Because of inflation. Why is entropy so high? Because we live in a multiverse. If we categorically reject ideas in science just because they feel crazy, we will probably reject whatever the correct theory is, too. The Universe has to be so that we like it. As Feynman said: If you don't like it, go somewhere elese.