Brett,
  I appreciate your style, which is in keeping with the modus operandus of =
physics with which I am most familiar.  Sometimes to an outsider, the heate=
d exchanges of my profession might look to an outsider at a gathering, as t=
hough a 'knock down, drag out fight' was about to erupt.  But after the 'du=
st settles'around those engaged passionately in their pursuit of scientific=
 truth, everybody remains friends (in some cases, even best friends).
   I have alienated some professional seismologists because I thought it sh=
ould be natural for virtually all scientists to relate to one another in su=
ch a spirited dynamic manner.  So the 'point/counterpoint' discussions in w=
hich you and I have been involved is like a 'fresh cool wind on a hot summe=
r Georgia day'--something that I very much enjoy. But contrast our exchange=
s with something that illustrates my inability to do the same thing with th=
e pro's.  To cite just one example, I wrote a paper titled "The cumulative =
spectral power--a new tool for seismology".  Out of naivete, I thought that=
 the inclusion of a direct reference to seismology in the title of this art=
icle would help to open meaningful dialogue with them. It appears that my c=
hoice of title actually caused just the opposite.   Although I know from ci=
rcumstances of mostly accidental type, that some seismologists have read (a=
nd maybe some are still reading) this paper; not a single person of that pe=
rsuasion has from his own initiative ever told me so.  And it appears (perh=
aps I'm just paranoid) that 'hell would freeze over' before any one of them=
 would reference the article in some paper they might write (unless their e=
ffort should prove to be inextricably connected, and/or influenced at its c=
ore by mine). On the other hand, the CSP concept that I advanced in that pa=
per has been 'picked up and touted to be novel and worthwhile' by some othe=
r reputable scientists and engineers.
     Out of some stubborn seat of arrogance I am not simply trying to win a=
 fight with you. To the best of my ability to gauge motive, I am trying for=
 my own edification to 'pick your brain and wrest a better understanding' f=
or each of two systems that are vastly different in size, though neverthele=
ss surprisingly still similar in some respects.  I view the objective to un=
derstand as much as is reasonably possible about both to be well worth the =
high price that has already been, and continues to be paid for their study.=
  They are:  (i) human body with emphasis on heart dynamics such as where I=
'm doing NIH sponsored seismocardiography research with Med School personne=
l, and (ii) intense studies of this planet for which you and I both have mu=
ch vested interest in trying to discover as much as we possibly can about i=
ts complexities.
   Much of my interest in both revolves around issues for which physics lea=
rned long ago how (for at least some cases) more is to be gained from a car=
eful consideration of quantitatively precise  and self-consistent frequency=
 domain calculations-- than is possible by restricting oneself to just time=
 domain data.  That is why I have so passionately tried to get seismologist=
s to use at least the (proper) power spectral density for mechanical system=
s, and to look at more than just their curves which are used almost exclusi=
vely to tout instrument performance.  For the many ones who continue to hol=
d fast to their belief that the most meaningful units for the PSD are m^2/s=
^4/Hz, there will always be an insurmountable handicap, ever present to res=
ist self consistency toward which science must always strive.  Stated in pl=
ain terms:  how can they cling so tenaciously to a set of units that is bla=
tantly incorrect for purpose of the 'greater good of seismology'?.  Such st=
ubbornness may be why the pro's rarely consider PSD for any other purpose t=
han to generate a curve with which to see if their instrument can resolve s=
ite noise at the level of the "Peterson model" and/or (for commercial instr=
ument builders) convince potential customers that their seismograph is supe=
rior to those of their competitors.
   Having said all the above (probably more than is warranted in the minds =
of most), I want to try and influence you to consider a possibly different =
perspective concerning the greater 'noise' that you mention as being associ=
ated with horizontal as compared to vertical instruments.  I have known of =
these differences for at least a decade because of the great attention give=
n to the subject in the vast seismology literature.  Many of us are intimat=
ely familiar with the fact that the horizontal instruments are quite differ=
ently (much more greatly) influenced by tilt than is true of the vertical o=
nes.  There was an early tilt controversy worthy of note.  Early on in seis=
mology it was not really understood that the tilt component of earthquake w=
aves did not play a significant role in the most 'important' response of a =
conventional seismograph to an earthquake.  Although the proof can also be =
found in articles written by others, years earlier than myself;  I show in =
my BSSA tutorial why this is the case.  (For reason of grace by the SSA to =
authors, there is no copyright violation associated with my posting this tu=
torial on my webpage where anybody who is interested can read the tutorial =
in its entirety, as opposed to the usual availability of only an abstract).=
  http://physics.mercer.edu/hpage/BSSA-tutorial/pend-theory.pdf
   What is shown there is that wave periods have to be in the several hundr=
ed seconds range before the tilt component of the wave is of comparable mag=
nitude to the acceleration component.  My greatest interest in seismology h=
as been focused on these long-period earth motions where tilt is the domina=
nt source of influence on a seismic instrument of horizontal type.  Of cour=
se in the shorter period range of conventional earthquake monitoring, the m=
otions involving tilt, that derive largely from local to mesoscale atmosphe=
ric pressure gradient changes, is an aggravation.  Also, keep in mind that =
I am not as interested in waves as much as what amounts to 'shape changes' =
that influence the earth's field to which the direction of the pendulum is =
sensitive.
    Consider the gravitational simple pendulum that hangs in the direction =
(like a plomb bob) of the local earth field little g, whose value is near 9=
..8 m/s^2 nearly everywhere on the surface of the earth.  A good gravimeter =
(such as the classic instruments sold by LaCoste Romberg) can measure the m=
agnitude of g to micro-gal levels (gal being 1 cm/s^2). But to first order =
the gravimeter is by contrast almost invariant to direction changes in g (w=
hich is a good thing).  A pendulum in the form of a sophisticated plomb bob=
 can, however, be made to measure direction changes in g to nano-radian lev=
els while simultaneously to first order being invariant to magnitude change=
s (which is also a good thing from my perspective).  When the earth changes=
 its configuration (changes in shape) whether by subduction that ultimately=
 gives rise to an earthquake--or in oscillatory manner (somewhat like a vib=
ratory spherical glob of weightless water held together by surface tension,=
 that our astronauts used to demonstrate with tea expelled from the mouth) =
there are always (at  places determined by the nodes of the spherical harmo=
nics that describe the motion) direction changes that can be observed with =
a pendulum having nano-radian sensitivity.
    So my claim is that the properties of the pendulum that are for you a c=
ursing-- can for me (and I also hope eventually for  some others) be instea=
d a source of blessing. It's kind of in the category of the old saying, "on=
e man's garbage can be another man's treasure'.  That is the kind of force-=
balance pendulum that I was thinking about when I mentioned the instrument =
type for which I would be willing to 'sing'.  If you can convince me that G=
ary Lindgren has already built such an instrument, then I am ready to 'make=
 a joyful sound'.  But only if he can show me evidence that his instrument =
is able to detect precursors to earthquakes, of the type I  view as potenti=
ally able to provide early warning life saving capability (few hours prior =
to a devastating event) and that he can also (concomitantly) see low order =
eigenmode oscillations of the earth, at least after big earthquakes.   If h=
is force-balance electronics is one that gives an output from the electroni=
cs that corresponds to the time derivative of what amounts to the equivalen=
t to pendulum displacement, then I will be skeptical.  I know from Erhard W=
ielandt that your instruments should also be able to output the 'accelerati=
on'  as opposed to the usual the 'velocity'.
      I hope that with this discourse you might be able to at least begin t=
o appreciate my belief that there can be 'physics of value in noise', even =
for some noises that ostensibly appear altogether detestable.  Incidentally=
, several years ago I found a paper written in the 1960's by a respected se=
ismologist named Rogers (if my memory of his name serves me correctly), tha=
t says pretty much the same thing as my comments above.  He pointed out the=
 fact that horizontal instruments of various types should be able to be con=
figured to see earth oscillations (for the reasons I have just discussed). =
 If you are interested I will try to dig through my stuff and give you a ci=
tation to his article.

  Best regards,
Randall
Brett,
  I appreciate your style, which is in keepi=
ng with the modus operandus of physics with which I am most familiar. =
 Sometimes to an outsider, the heated exchanges of my profession might look=
 to an outsider at a gathering, as though a 'knock down, drag out fight' wa=
s about to erupt.  But after the 'dust settles'around those engaged pa=
ssionately in their pursuit of scientific truth, everybody remains friends =
(in some cases, even best friends).  
   I have alienated some professional seismologists becau=
se I thought it should be natural for virtually all scientists to relate to=
 one another in such a spirited dynamic manner.  So the 'point/counter=
point' discussions in which you and I have been involved is like a 'fresh c=
ool wind on a hot summer Georgia day'--something that I very much enjoy. Bu=
t contrast our exchanges with something that illustrates my inability to do=
 the same thing with the pro's.  To cite just one example, I wrote a p=
aper titled "The cumulative spectral power--a new tool for seismology&=
quot;.  Out of naivete, I thought that the inclusion of a direct refer=
ence to seismology in the title of this article would help to open meaningf=
ul dialogue with them. It appears that my choice of title actually caused j=
ust the opposite.   Although I know from circumstances of mostly =
accidental type, that some seismologists have read (and maybe some are stil=
l reading) this paper; not a single person of that persuasion has from his =
own initiative ever told me so.  And it appears (perhaps I'm just para=
noid) that 'hell would freeze over' before any one of them would reference =
the article in some paper they might write (unless their effort should prov=
e to be inextricably connected, and/or influenced at its core by mine). On =
the other hand, the CSP concept that I advanced in that paper has been 'pic=
ked up and touted to be novel and worthwhile' by some other reputable scien=
tists and engineers.  
  =
   Out of some stubborn seat of arrogance I am not simply tr=
ying to win a fight with you. To the best of my ability to gauge motive, I =
am trying for my own edification to 'pick your brain and wrest a better und=
erstanding' for each of two systems that are vastly different in size, thou=
gh nevertheless surprisingly still similar in some respects.  I view t=
he objective to understand as much as is reasonably possible about both to =
be well worth the high price that has already been, and continues to be pai=
d for their study.  They are:  (i) human body with emphasis on he=
art dynamics such as where I'm doing NIH sponsored seismocardiography resea=
rch with Med School personnel, and (ii) intense studies of this planet for =
which you and I both have much vested interest in trying to discover as muc=
h as we possibly can about its complexities. 
   Much of my interest in both revolves around issues =
for which physics learned long ago how (for at least some cases) more is to=
 be gained from a careful consideration of quantitatively precise  and=
 self-consistent frequency domain calculations-- than is possible by restri=
cting oneself to just time domain data.  That is why I have so passion=
ately tried to get seismologists to use at least the (proper) power spectra=
l density for mechanical systems, and to look at more than just their curve=
s which are used almost exclusively to tout instrument performance.  F=
or the many ones who continue to hold fast to their belief that the most me=
aningful units for the PSD are m^2/s^4/Hz, there will always be an insurmou=
ntable handicap, ever present to resist self consistency toward which scien=
ce must always strive.  Stated in plain terms:  how can they clin=
g so tenaciously to a set of units that is blatantly incorrect for purpose =
of the 'greater good of seismology'?.  Such stubbornness may be why th=
e pro's rarely consider PSD for any other purpose than to generate a curve =
with which to see if their instrument can resolve site noise at the level o=
f the "Peterson model" and/or (for commercial instrument builders=
) convince potential customers that their seismograph is superior to those =
of their competitors.  
  =
; Having said all the above (probably more than is warranted in the mi=
nds of most), I want to try and influence you to consider a possibly differ=
ent perspective concerning the greater 'noise' that you mention as being as=
sociated with horizontal as compared to vertical instruments.  I have =
known of these differences for at least a decade because of the great atten=
tion given to the subject in the vast seismology literature.  Many of =
us are intimately familiar with the fact that the horizontal instruments ar=
e quite differently (much more greatly) influenced by tilt than is true of =
the vertical ones.  There was an early tilt controversy worthy of note=
..  Early on in seismology it was not really understood that the tilt c=
omponent of earthquake waves did not play a significant role in the most 'i=
mportant' response of a conventional seismograph to an earthquake.  Al=
though the proof can also be found in articles written by others, years ear=
lier than myself;  I show in my BSSA tutorial why this is the case.&nb=
sp; (For reason of grace by the SSA to authors, there is no copyright viola=
tion associated with my posting this tutorial on my webpage where anybody w=
ho is interested can read the tutorial in its entirety, as opposed to the u=
sual availability of only an abstract).  http://physics.mercer.edu/hpa=
ge/BSSA-tutorial/pend-theory.pdf
 &=
nbsp; What is shown there is that wave periods have to be in the several hu=
ndred seconds range before the tilt component of the wave is of comparable =
magnitude to the acceleration component.  My greatest interest in seis=
mology has been focused on these long-period earth motions where tilt is th=
e dominant source of influence on a seismic instrument of horizontal type.&=
nbsp; Of course in the shorter period range of conventional earthquake moni=
toring, the motions involving tilt, that derive largely from local to mesos=
cale atmospheric pressure gradient changes, is an aggravation.  Also, =
keep in mind that I am not as interested in waves as much as what amounts t=
o 'shape changes' that influence the earth's field to which the direction o=
f the pendulum is sensitive.  
&nbs=
p;   Consider the gravitational simple pendulum that hangs i=
n the direction (like a plomb bob) of the local earth field little g, whose=
 value is near 9.8 m/s^2 nearly everywhere on the surface of the earth.&nbs=
p; A good gravimeter (such as the classic instruments sold by LaCoste Rombe=
rg) can measure the magnitude of g to micro-gal levels (gal being 1 cm/s^2)=
.. But to first order the gravimeter is by contrast almost invariant to dire=
ction changes in g (which is a good thing).  A pendulum in the form of=
 a sophisticated plomb bob can, however, be made to measure direction chang=
es in g to nano-radian levels while simultaneously to first order being inv=
ariant to magnitude changes (which is also a good thing from my perspective=
).  When the earth changes its configuration (changes in shape) whethe=
r by subduction that ultimately gives rise to an earthquake--or in oscillat=
ory manner (somewhat like a vibratory spherical glob of weightless water he=
ld together by surface tension, that our astronauts used to demonstrate wit=
h tea expelled from the mouth) there are always (at  places determined=
 by the nodes of the spherical harmonics that describe the motion) directio=
n changes that can be observed with a pendulum having nano-radian sensitivi=
ty.
    So my claim is th=
at the properties of the pendulum that are for you a cursing-- can for me (=
and I also hope eventually for  some others) be instead a source of bl=
essing. It's kind of in the category of the old saying, "one man's gar=
bage can be another man's treasure'.  That is the kind of force-balanc=
e pendulum that I was thinking about when I mentioned the instrument type f=
or which I would be willing to 'sing'.  If you can convince me that Ga=
ry Lindgren has already built such an instrument, then I am ready to 'make =
a joyful sound'.  But only if he can show me evidence that his instrum=
ent is able to detect precursors to earthquakes, of the type I  view a=
s potentially able to provide early warning life saving capability (few hou=
rs prior to a devastating event) and that he can also (concomitantly) see l=
ow order eigenmode oscillations of the earth, at least after big earthquake=
s.   If his force-balance electronics is one that gives an output=
 from the electronics that corresponds to the time derivative of what amoun=
ts to the equivalent to pendulum displacement, then I will be skeptical.&nb=
sp; I know from Erhard Wielandt that your instruments should also be able t=
o output the ‘acceleration’  as opposed to the usual the &=
#8216;velocity’.  
 &nbs=
p;    I hope that with this discourse you might be able=
 to at least begin to appreciate my belief that there can be 'physics of va=
lue in noise', even for some noises that ostensibly appear altogether detes=
table.  Incidentally, several years ago I found a paper written in the=
 1960's by a respected seismologist named Rogers (if my memory of his name =
serves me correctly), that says pretty much the same thing as my comments a=
bove.  He pointed out the fact that horizontal instruments of various =
types should be able to be configured to see earth oscillations (for the re=
asons I have just discussed).  If you are interested I will try to dig=
 through my stuff and give you a citation to his article.  =
 
  B=
est regards,
Randall
=