Inspired by the thread on Perpetual motion and Inertia, I have a question that has bothered me some over the years.
So Newton’s law says “ Every body in the universe keeps at rest or uniform rectilinear motion unless and until an outside force acts on it”
While one interpretation of the Third Law of Thermodynamics is that Entropy of a system increases with time (or the direction of time is the same as the direction of increasing entropy).
To rationalize the above two, is Thermodynamics saying that there will always be something opposing motion (like friction ).
Or maybe put another way, is it thermodynamically possible to eliminate all friction ?
Says that even superconductors have non zero resistance (in pico ohms ) which is sort of like the friction planets experience. To have perfect superconductors you will need perfectly pure materials which entropy again won’t permit (?) in the real world.
Superconductors, both theoretically and through experiment, have true zero resistance to DC currents. Experiments run over multiple years using superconducting loops cannot detect any current decay outside of the error bars of the experiment. Any time variation (AC, however slowly varying) in the current introduces finite resistance.
A superconducting loop only needs a fully connected path of superconductivity to exhibit this behavior (the pair current only flows in the superconducting portions of the loop, the normal state portions aren’t involved), so impurities will have much less effect than one would expect from an understanding of metals and alloys. I’m not sure if there are any quantum uncertainty effects that can introduce decay, but my instinct is to doubt that quantum fluctuations can reach the energy needed to affect the single wave function that exists around a DC loop.
Mechanically, superfluid He should also have persistent flows that, once started, don’t decay. I’m not sure there is any experiment analogous to the superconducting loop in superfluid He, but if there is, it’s certainly been tried.
Both superconductivity and superfluidity are examples of “macroscopic quantum effects”. As I once explained to an engineer, if you make a SQUID with a loop that is a mile in circumference, as long as you keep that entire SQUID cold, it can be a single qubit.
I think OP’s question has been answered — (can’t we agree that extremely tiny friction and zero friction are almost the same as each other and just get along? ) — so related questions are in order.
The article suggests that England is neither a crackpot, nor is he just repeating the obvious:
I did not attempt to write a multi-paragraph summary between the URL and /URL tags — though it was predictable that nobody would click. England’s controversial paper develops the math of non-equilibrium thermodynamics, and even suggests that different thermodynamic properties of DNA and RNA may explain why life uses two different nucleic acids! (For example, “Thus, surprisingly, the greater fragility of RNA could be seen as a fitness advantage in the right circumstances”) I need to re-read — and still wouldn’t be qualified to summarize. But if none of our experts wants to help put this all in context, that’s fine.
) — so related questions are in order.