In regards to hopping and third fingers:
If you have physical movement, there is energy manifesting itself. I've never heard of a case in which it was reported on plain carbon and some not so plain carbons.
Usually it's inconel, stainless, etc. For the theory of magnetism, the Titanium element that is also witnessed would seem to throw that theory out, as Ti is not ferromagnetic. (I believe it is diamagnetic). For that material, the amount of current necessary to set up a magnetic field would be phenomenal and highly unlikely.
If it was not for seeing it in ti it would be easy to attribute it to magnetism, as the other materials mentioned contain nickel which is ferromagnetic. However, Iron is ferromagnetic , so what common thread do the materials experiencing this hopping phenomenon have? (ferromagnetic, diamagnetic, and paramagnetic materials)
None I've ever heard of are carbon, the ones that have been reported are all higher end alloys consisting of nickel, titanium, moly, chromium, and a host of others. The exception to these materials is in carbon content, and iron content.
For that reason, I'll add my pet hypothesis to the fray.
EMAT stands for electromagnetic acoustic transmission. It is a UT method that sets up partical vibration via electromagnetic eddy currents.
http://www.ndt.net/ndtaz/content.php?id=144It is also well known to the UT types that current can set up this vibration, it is also known that heating can do the same thing. (Localized induction of ultrasonic and infrasonic vibrations via localized laser heating have been documented and are under R&D in many places for use in NDE)
Resonance
http://www.ndt.net/ndtaz/content.php?id=284http://www.kettering.edu/~drussell/demos.htmlIt's my opinion, it's a resonance harmonics in either the infrasonic, or subsonic range that sets up these mechanical vibrations.
The carbon and iron content of standard carbons may just not be capable of generating this harmonic resonance due to their natural frequency as modified by their grain structure and size.
My two cents worth,
Gerald