Thanks for your comments, Bob.  It does my heart good to hear folks finally=
 talk about low level latching of mechanical oscillators.  I spent the last=
 twenty years
of my career (finally retiring fully this past spring from Mercer Universit=
y) trying to understand subtleties of friction, especially the internal fri=
ction type
that derives from defects in solids.
           One of the first occasions for me to study magnetic levitation w=
as about fifty years ago as a freshman physics major at the
Univ. of Tennessee (in Prof. Oliver Thomson's laboratory).  Aware of the pi=
oneering work by Prof. Jesse Beams at the Univ. of Virginia, I built an ele=
ctromagnet system with feedback involving output from an optical sensor --t=
o levitate a steel ball bearing.  I was amazed at the seeming absence of fr=
iction influence on the ball for that system; even though my ball was suspe=
nded in air.
          Professor Beams used to spin such a ball in a high vacuum by mean=
s of an ever increasing frequency of an externally applied, rotating magnet=
ic field.   By this means he actually demonstrated a method to tear the bal=
l apart.  At some critical point, as the angular frequency was increased to=
ward phenomenally high values, the centripetal forces of rotation became so=
 large that the steel ruptured.  His method was also used to study diffusio=
n of atoms in a metal, since a very large gradient could thus be establishe=
d.  His experiments were widely acclaimed, and the lab named in his honor i=
s worth a visit at
http://www.virginia.edu/webmap/popPages/76-PhysicsBldg_Jesse.html
Suffice it to say, Beams could never have become famous for his pioneering =
solid state physics contributions (ultracentrifuge work) if his magnetic fi=
elds were exhibiting some kind of friction derived from magnetic hysteresis=
..  Although his permanent magnets were probably an alloy of aluminum, nicke=
l and cobalt (called alnico), there is little reason to believe that the ra=
re earth types that
have come along after his work-should show some bizarre physical property n=
ot possible with alnico.
    Now about the matter of the other extreme-'low and slow' motions.  My c=
areer has been devoted to the intense study of internal friction in this re=
gime.   I've done
more than most, when it comes to  'gravitational pendulums' outfitted with =
a sensor that allows reasonable quantitative study of low level, long perio=
d mechanical oscillators.  I jokingly tell folks, it's because "when one ha=
s only a hammer for a tool, everything looks like a nail".
     I became interested in the magnetic levitation case for the very reaso=
n that you claim to be impossible; i.e., that the materials (whether PG pla=
te or rare earth
magnets, or both) must be afflicted with some presently unknown structural =
property that gives rise to latching at low levels of small inertial mass o=
scillators.
I find no evidence from my system to support your claim, based on my invest=
igations of the prototype that is described in the article that I mentioned=
 to this list serve.
That paper does not show andy figures relevant to the regime being discusse=
d, but just today I analyzed a record corresponding to noise in the output =
from the covered instrument while it was 'undisturbed'.  It is also worthy =
of note that I had made a change to the instrument; i.e., decreased the gap=
 spacing between the PG plates and the upper electrode array-which increase=
d  the sensitivity by about ten fold.  Whatever the nature of the ambient n=
oise during this time, I have good reason (from other studies with my Volks=
Meter under similar conditions) to believe that those noises are extremely =
small and derive from low level surface motions of the Earth that are of co=
mmon type, for places other than the truly 'quiet' places of our planet, as=
  sometimes noted by folks like Dr.  Jon Berger at Scripps Inst., UCSD.
     So what was seen?  At times, infinitesimal noise driven motion (visibl=
e as a fairly sharp spectral line in the FFT ) at the characteristic period=
 of the instrument, about 0.6 s.  The quality factor of the instrument appe=
ars thus to be virtually unaffected by the amplitude of the motion; which m=
eans there cannot be any latching of the type you indicated.  My expectatio=
n is that Chris Chapman's comment may be responsible for what you observed-=
i.e., the presence of lint, hairs, or dust, interacting as a 'show stopper'=
 with your low mass oscillating member.  I have seen this also to be true i=
f I wasn't careful to eliminate such intruders.  The mass of my plates is o=
nly about 2 g, and so anything of the type Chris mentioned will 'lock it up=
'.
       I was also very interested, Meredith, in your comments about the imp=
ortance of shape irregularities in the PG plates.  Indeed, you can see from=
 the photographs of my paper that my plates are (as you found) anything but=
 a smooth planar surface after the cleaving that I did.  But one of the gre=
atest features of my capacitive sensors is their relative immunity (compare=
d to optical detectors) to such imperfections of construction.  When I firs=
t began years ago to work with crudely built components I was astonished at=
 this their property.   So the possibility of this instrument serving as th=
e basis for a useful, new type of seismograph-looks ever more promising to =
me.
     Randall
Thanks for your =
comments, Bob.  It does my heart good to hear folks finally talk about=
 low level latching of mechanical oscillators.  I spent the last twent=
y years
of my career (finally retiring f=
ully this past spring from Mercer University) trying to understand subtleti=
es of friction, especially the internal friction type
that derives from defects in solids.  
         &nb=
sp; One of the first occasions for me to study magnetic levitation was=
 about fifty years ago as a freshman physics major at the
Univ. of Tennessee (in Prof. Oliver Thomson’s labor=
atory).  Aware of the pioneering work by Prof. Jesse Beams at the Univ=
.. of Virginia, I built an electromagnet system with feedback involving outp=
ut from an optical sensor --to levitate a steel ball bearing.  I was a=
mazed at the seeming absence of friction influence on the ball for that sys=
tem; even though my ball was suspended in air.
          Professor Bea=
ms used to spin such a ball in a high vacuum by means of an ever increasing=
 frequency of an externally applied, rotating magnetic field.   B=
y this means he actually demonstrated a method to tear the ball apart. =
; At some critical point, as the angular frequency was increased toward phe=
nomenally high values, the centripetal forces of rotation became so large t=
hat the steel ruptured.  His method was also used to study diffusion o=
f atoms in a metal, since a very large gradient could thus be established.&=
nbsp; His experiments were widely acclaimed, and the lab named in his honor=
 is worth a visit at
http://www.virgi=
nia.edu/webmap/popPages/76-PhysicsBldg_Jesse.html
Suffice it to say, Beams could never have become famous for h=
is pioneering solid state physics contributions (ultracentrifuge work) if h=
is magnetic fields were exhibiting some kind of friction derived from magne=
tic hysteresis.  Although his permanent magnets were probably an alloy=
 of aluminum, nickel and cobalt (called alnico), there is little reason to =
believe that the rare earth types that
h=
ave come along after his work—should show some bizarre physical prope=
rty not possible with alnico. 
 &nb=
sp;  Now about the matter of the other extreme—‘low a=
nd slow’ motions.  My career has been devoted to the intense stu=
dy of internal friction in this regime.   I’ve done
more than most, when it comes to  ‘g=
ravitational pendulums’ outfitted with a sensor that allows reasonabl=
e quantitative study of low level, long period mechanical oscillators. =
; I jokingly tell folks, it’s because “when one has only a hamm=
er for a tool, everything looks like a nail”.  
     I became interested in the=
 magnetic levitation case for the very reason that you claim to be impossib=
le; i.e., that the materials (whether PG plate or rare earth
=
magnets, or both) must be afflicted with some presentl=
y unknown structural property that gives rise to latching at low levels of =
small inertial mass oscillators.   
I find no evidence from my system to support your claim, based on my =
investigations of the prototype that is described in the article that I men=
tioned to this list serve.  
That p=
aper does not show andy figures relevant to the regime being discussed, but=
 just today I analyzed a record corresponding to noise in the output from t=
he covered instrument while it was ‘undisturbed’.  It is a=
lso worthy of note that I had made a change to the instrument; i.e., decrea=
sed the gap spacing between the PG plates and the upper electrode arrayR=
12;which increased  the sensitivity by about ten fold.  Whatever =
the nature of the ambient noise during this time, I have good reason (from =
other studies with my VolksMeter under similar conditions) to believe that =
those noises are extremely small and derive from low level surface motions =
of the Earth that are of common type, for places other than the truly ̵=
6;quiet’ places of our planet, as  sometimes noted by folks like=
 Dr.  Jon Berger at Scripps Inst., UCSD.  
     So what was seen?  At times=
, infinitesimal noise driven motion (visible as a fairly sharp spectral lin=
e in the FFT ) at the characteristic period of the instrument, about 0.6 s.=
  The quality factor of the instrument appears thus to be virtually un=
affected by the amplitude of the motion; which means there cannot be any la=
tching of the type you indicated.  My expectation is that Chris Chapma=
n’s comment may be responsible for what you observed—i.e., the =
presence of lint, hairs, or dust, interacting as a ‘show stopper̵=
7; with your low mass oscillating member.  I have seen this also to be=
 true if I wasn’t careful to eliminate such intruders.  The mass=
 of my plates is only about 2 g, and so anything of the type Chris mentione=
d will ‘lock it up’.    
       I was also very inte=
rested, Meredith, in your comments about the importance of shape irregulari=
ties in the PG plates.  Indeed, you can see from the photographs of my=
 paper that my plates are (as you found) anything but a smooth planar surfa=
ce after the cleaving that I did.  But one of the greatest features of=
 my capacitive sensors is their relative immunity (compared to optical dete=
ctors) to such imperfections of construction.  When I first began year=
s ago to work with crudely built components I was astonished at this their =
property.   So the possibility of this instrument serving as the =
basis for a useful, new type of seismograph—looks ever more promising=
 to me. 
     R=
andall
 
=