I think the answer to your question about gradual decoherence of the magnetic domains might actually be the opposite. Remember your old horseshoe magnets? They were always stored with a "keeper" so as to keep the magnetic field strong. I think what would happen over time is that the magnet will align itself for minimum energy (due to thermal dither), and minimum energy when there is a magnetic material (reluctor) on the magnet means gradual alignment of the domains to include the reluctor as part of the minimum energy solution.
In the case of a superconductor, don't forget that a superconductor is only zero resistance for DC (F=0). True DC has been held constant from -inf to +inf for all time. At some point in a superconducting magnet, current must be added once the superconducting state is achieved. This may typically be a ramp in current, but it boggles me somewhat to understand how a true 0 frequency component is introduced into the superconductor. While the storage of that current does not require work, it requires a great deal of work to load that current into the superconductor. I think something similar can be said about the magnet and the ring in the photo. Just like the weight on the table is not doing work even though it has potential energy, something put that potential energy into the system by doing work in the first place. On Sat, Nov 14, 2015 at 12:02 AM, Eric Walker <eric.wal...@gmail.com> wrote: > On Sat, Nov 14, 2015 at 12:25 AM, David Roberson <dlrober...@aol.com> > wrote: > > I consider electrons in orbits as being equivalent to a superconductor >> current since the orbits do not collapse with time. No power is radiated >> by an electron orbital and hence no work is required to keep it in the >> proper location. >> > > Another way to come at the question I just raised is this -- even though > the electrons may be superconducting in their orbits, is there something > the force of a weight that is held up might do to gradually decohere the > magnetic domains? > > Eric > >
