The double entry accounting system is over five centuries old. While commerce and technology have changed in dramatic and unforeseen ways, the double entry system continues to survive and even thrive. The reasons for its durability and longevity remain something of a mystery. Entropy, Double Entry Accounting and Quantum Entanglement speculates on the reasons for double entry accounting's apparent usefulness. The monograph is organized as follows. Section 2 establishes the three-way classical equivalence. Section 3 establishes the three-way quantum equivalence. The classical equivalence is a...