This study demonstrates that "entropy" is not a physical quantity, i.e., there is no physical quantity called "entropy". When heat engine efficiency is defined as: η=W/W1, and the reversible cycles is decided to be Stirling cycle, ifÃ?¢Ã?Ë?Ã?®dQ/T=0 is established, we can proveÃ?¢Ã?Ë?Ã?®dW/T=0 andÃ?¢Ã?Ë?Ã?® d/T=0. If consideringÃ?¢Ã?Ë?Ã?®dQ/T=0,Ã?¢Ã?Ë?Ã?®dW/T=0 and Ã?¢Ã?Ë?Ã?®dE/T=0 have defined new system state variables, It would be ridiculous to show such a definition. The fundamental error of "entropy" is that the polytropic process function Q is not a single-valued function of T in any reversible process, P-V figure should be P-V-T figure, so Σ[(Q)/T)] becoming ∫dQ/T is untenable. As a result,Ã?¢Ã?Ë?Ã?®dQ/T=0, Ã?¢Ã?Ë?Ã?® dW/T=0 andÃ?¢Ã?Ë?Ã?® dE/T=0 are all untenable, namely, there is not such formula asÃ?¢Ã?Ë?Ã?® dQ/T=0,Ã?¢Ã?Ë?Ã?® dW/T=0 andÃ?¢Ã?Ë?Ã?®dE/T=0 at all. Since the "absolute entropy" of Boltzmann is used to explain Clausius’ "entropy" and the unit (J/K) of Boltzmann’s "entropy" is also transplanted from the Clausius’ "entropy", it is at the same time denied
