Maybe you can answer the following question and simply tell me if it's a st=
upid hypothetical scenario?
     Years ago as I thought about force balance applied to seismology, I th=
ought about the following.
Why not take a simple 'mass measuring instrument (like a commercial Mettler=
 laboratory balance)' that also uses force feedback; and 'jazz up the elect=
ronics' to look at earthquakes with it?  I assume that the obvious limitati=
on of so doing derives from the fact that the 'natural period' of this pack=
age, without the feedback, is prohibitively short.  And we all know that pe=
riod lengthening is what yields high sensitivity.  It is a simple matter to=
 show that the sensitivity of an 'electronics-less' instrument is proportio=
nal to the square of the period.  In the case of a pendulum I will (for any=
body interested) describe how this works in a manner that is very easy to u=
nderstand.  For other instruments you have to use more challenging mathemat=
ics.
     Now if you say, "yes Peters, this cannot work for the reason you just =
gave; then explain to me why not.   If you claim that the over-riding const=
raint is the electronics, then we immediately have another challenge; i.e. =
what do we do to improve the electronics to make it possible?  On the other=
 hand, if the electronics is indeed adequate to the task-then I can only co=
me to the following conclusion-that it cannot work because of a spring prob=
lem!  After all, perfectly adequate electronics should compensate for any d=
egree of hardness in a perfect Hooke's law spring.
      If you agree with my conclusion, then you must also recognize that th=
ere is more to the complexity of springs than we have naively assumed.
Randall

Maybe you can an=
swer the following question and simply tell me if it’s a stupid hypot=
hetical scenario?
   &nbs=
p; Years ago as I thought about force balance applied to seismology, I thou=
ght about the following.
Why not take a =
simple ‘mass measuring instrument (like a commercial Mettler laborato=
ry balance)’ that also uses force feedback; and ‘jazz up the el=
ectronics’ to look at earthquakes with it?  I assume that the ob=
vious limitation of so doing derives from the fact that the ‘natural =
period’ of this package, without the feedback, is prohibitively short=
..  And we all know that period lengthening is what yields high sensiti=
vity.  It is a simple matter to show that the sensitivity of an ‘=
;electronics-less’ instrument is proportional to the square of the pe=
riod.  In the case of a pendulum I will (for anybody interested) descr=
ibe how this works in a manner that is very easy to understand.  For o=
ther instruments you have to use more challenging mathematics.  <=
/o:p>
     Now if you say,=
 “yes Peters, this cannot work for the reason you just gave; then exp=
lain to me why not.   If you claim that the over-riding constrain=
t is the electronics, then we immediately have another challenge; i.e. what=
 do we do to improve the electronics to make it possible?  On the othe=
r hand, if the electronics is indeed adequate to the task—then I can =
only come to the following conclusion—that it cannot work because of =
a spring problem!  After all, perfectly adequate electronics should co=
mpensate for any degree of hardness in a perfect Hooke’s law spring.<=
o:p>
      If you ag=
ree with my conclusion, then you must also recognize that there is more to =
the complexity of springs than we have naively assumed.
Randall
 
=