2nd Law vs Perpetual Motion

A physicist would say that perpetual motion is impossible, because by the 2nd Law of Thermodynamics there is always some positive loss of energy from some form of friction, which even a best possible engineer cannot turn off. In a fluid the friction energy takes the form of turbulent dissipation into heat energy. But on the question why there must be some loss, the answer would be vague probably with some reference to statistics, Boltzmann's H-theorem and entropy as disorder.

Let us see if the Physical 2nd Law I have described in recent posts can give an answer with more physical substance. The basic idea is that real physics is a form of analog computation, which can be mimicked in digital computation and that in both cases the computation has finite precision. In real physics that may be set by the smallest physical scale and in computation by the computational mesh. A most remarkable conjectured by Kolmogorov, is that turbulent dissipation rate is independent of the absolute size of the smallest scale, because turbulent energy is transferred in a cascade to dissipate at smallest scale. 

This is confirmed in the book Computational Turbulent Incompressible Flow, which means that turbulent flow is computable without mesh resolution to physical scale and so opens a new window in fluid mechanics.  

It also shows that it is impossible to decrease the loss/turbulent dissipation by refining the precision into a finer model and finer mesh. In other words, it is impossible to bring loss to zero and realise perpetual motion. Because of finite precision.

The notion of finite precision present in both analog and digital physics thus opens to a new understanding of the 2nd Law and why it makes perpetual motion impossible to realise. More substance is given in Computational Thermodynamics.

The 2nd Law does not apply to the microscopics of a hydrogen atom in ground state with an electronic change in time like a harmonic oscillator without change of electron density and then without friction as described on Real Quantum Mechanics. But a radiating atom with electron density changing over time is subject to radiative loss, which must be balanced by an exterior force in sustained motion. The 2nd Law thus is relevant on all scales, not just for macroscopic ensembles of many.