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and what about superconducting current? This surely is not microscopic.
I also doubt that ferromagnetic domain is really microscopic. Could you give any argument?
In muy opinion magnetic domain consists of milion of atoms and is rather macroscopic.
We can also may consider ferromagnet in external magnetis field. Then we see macroscopic current.

First, you're misstating the problem.  Second, it didn't specifically refer to electrical currents but more general thermal currents, so stop using electrical examples when that's not what's meant.  The internal state of a ferromagnetic material is not changing in time when it is in thermal equilibrium, meaning no flow of thermally-related properties between parts of the system.  Superconductors in thermal equilibrium do also indeed operate in a constant state when isolated, there's no net macroscopic flow of their thermal (or electrical, it's not like charge just suddenly builds up someplace once a steady exchange has been established, or that the magnetic field surrounding the system will simply spike at random) properties within the system when properly isolated.


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Dr. Stephen O. Nelson


I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.


I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

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