The Entropy Paradox in the Chapman-Jouguet Theory of Detonation

The Chapman-Jouguet theory of detonation waves (circa 1905) predicts propagation speeds in gaseous systems to within 2{\%} of experimental values in most cases. In spite of this success, the theory was criticized early on by investigators who claimed that the accuracy of the CJ solution was just a lucky accident. The solution represents an entropy minimum of the final state, which is thermodynamically unstable. We show, however, that the original entropy-minimum argument was made erroneously, thus resolving a 100-year-old paradox.