I would really like to be able to observe and measure this
effect. And in that, I am reminded of the words of Lord Kelvin when
he writes: "I often say that when you can measure what you are
speaking about, and express it in numbers, you know something about
it; but when you cannot measure it, when you cannot express it in
numbers, your knowledge is of a meagre and unsatisfactory kind; it
may be the beginning of knowledge, but you have scarcely in your
thoughts advanced to the state of Science, whatever the matter may be."
I'd prefer to know something about it.
Brett,
Nothing you have said thus far encourages me more than your quote of K=
elvin. When I visited Glasgow and gave my lecture to James Hough=1B$B!G=1B=
(Bs group there (=1B$B!H=1B(BInstitute for Gravitational Research=1B$B!I=1B=
(B), one of the first things I noticed was that the physics building is nam=
ed after Kelvin. There is a legacy there which I wish were universal, but =
sadly it is not. Prof. Hough, who was made a Fellow of the Royal Society i=
n 2003, is committed to the same lofty goal as Thorne and troops at LIGO; i=
..e., be the first to actually see and measure gravitational waves. I was e=
specially impressed by his specific invitation to his elderly =1B$B!F=1B(Br=
etired=1B$B!G=1B(B physics mentor to come give an opinion on what I had to =
say. I have never been blessed more than by the positive feedback I receiv=
ed from this man. It tells me that Hough appreciates more than just knowle=
dge; he has great respect for the wisdom that comes only from having applie=
d that knowledge to practical systems.
There are some interesting quotes by other famous men that I think we s=
hould keep in mind while trying to extract understanding from the complexit=
ies of defect structures that have been seen, yet hardly studied in the way=
they need to be. Rutherford said,
=1B$B!H=1B(BAll of physics is either impossible or trivial. It is impossibl=
e until you understand it, and then it becomes trivial=1B$B!I=1B(B.
And perhaps we should all strive not to fall (for reason of vested interest=
s) into a trap of type that Einstein talked about,
"Only two things are certain: the universe and human stupidity; and I=1B$B!=
l=1B(Bm not certain about the universe."
It is not commonly known of Kelvin=1B$B!G=1B(Bs interest in some of t=
he same problems we=1B$B!G=1B(Bve been discussing. He was the first, with =
his helper George Darwin (son of the famous Charles) to look at the perplex=
ing diurnal swing of a simple gravitationally restored pendulum. Kelvin fi=
rst did so by hanging a mass where it could swing in one of the sturdy ston=
e doorways of the physics building. He was fascinated by the surprisingly =
complicated motions that he observed; so he and George created some elegant=
experimental techniques for monitoring such a pendulum long term over a wi=
de dynamic range. What they found proved beyond their resources capability=
to properly understand for modelling purposes.
The research that got me into much of the present business had its gen=
esis in Kelvin/Darwin=1B$B!G=1B(Bs studies. In the last decade NASA scient=
ist Jim Shirley asked me to try and verify a postulate of his. Because eac=
h of the Earth and moon moves about their barycenter (displaced 80 percent =
of the radius of the earth from its center), he expected we could measure a=
=1B$B!F=1B(Bredistributive force=1B$B!G=1B(B associated with the moon=1B$B=
!G=1B(Bs =1B$B!F=1B(Bwhipping=1B$B!G=1B(B the earth around in a circle with=
a period of one month.
I wouldn=1B$B!G=1B(Bt be surprised if Kelvin had thoughts about this po=
ssibility, although we couldn=1B$B!G=1B(Bt find specifics to prove this was=
so. Whereas he and Darwin were unable to bring closure to their efforts f=
or reason of their lack of an adequate tool (my, what he could have done wi=
th computers like we have today!), I haven=1B$B!G=1B(Bt been able to bring =
closure for reason of my stupidity, as compared to the genius of Kelvin (I =
learned while there that he enrolled conditionally at Glsogow as a young te=
en, and no doubt was =1B$B!F=1B(Bteaching his teachers=1B$B!G=1B(B before b=
eing awarded his first degree).
I want to close these comments with something else, for which I have be=
en like =1B$B!H=1B(Bthe voice of one crying in the wilderness=1B$B!G=1B(B. =
I believe, in the same spirit that motivated Kelvin to try and wrest under=
standing from experiment concerning the =1B$B!F=1B(Bbigger picture=1B$B!G=
=1B(B, that we should be doing something that (in my opinion) =1B$B!F=1B(Bc=
ries out=1B$B!G=1B(B to be studied. It has to do with the total power of s=
eismic type that can be quantified with our instruments. If you have your =
units right, then it is a straightforward matter to get these total seismic=
power numbers by simply integrating the power spectral density over its fu=
ll frequency range (the result being the maximum of my cumulative spectrum)=
-and then multiply your result by the mass of the earth (if you are clever =
enough to factor in a meaningful estimate for the frequency dependence for =
the Q of the earth). Why multiply by the mass of the earth? Duh? Becaus=
e what you are measuring is power in watts per kg. The same W/kg that your=
instrument measures, is by the application of Newton=1B$B!G=1B(Bs third la=
w, the W/kg with which the earth is causing your instrument to undergo acce=
lerations over a broad frequency range. (Kelvin would say =1B$B!F=1B(Byea =
and amen=1B$B!G=1B(B; why have you taken so long to bring trivial understan=
ding to a profoundly important question.)
So why is the total power of any importance? I talked with hurricane e=
xpert Kerry Emanuel about this and told him I was surprised by something. =
My estimates by this means (using Jon Berger=1B$B!G=1B(Bs data) of the tota=
l seismic power (energy in the solid part of the earth) is a bigger fractio=
n of the tidal power (braking of the earth=1B$B!G=1B(Bs rotation, easily an=
d routinely estimated) than I thought it should be. In other words, I thou=
ght more of the tidal power ought to be associated with waves of the oceans=
as opposed to vibrations of the crust. Kerry was fascinated with these th=
oughts, as he said =1B$B!H=1B(Bbecause there are some long-standing unsolve=
d problems involving oceanic flows (and their model=1B$B!G=1B(Bs inability =
to describe what is seen).
Keep up your good work, Brett.
Randall
I would really like =
to be able to observe and measure this
effect. And in that, I am reminded of the words of Lord Kelvin whe=
n
he writes: "I often say that =
when you can measure what you are
sp=
eaking about, and express it in numbers, you know something about
it; but when you cannot measure it, when you =
cannot express it in
numbers, your k=
nowledge is of a meagre and unsatisfactory kind; it
<=
p class=3DMsoNormal>may be the beginning of knowledge, but you have scarcely in=
your thoughts advanced to the state=
of Science, whatever the matter may be."
I'd prefer to know something about it.
Brett,
Nothing you have said t=
hus far encourages me more than your quote of Kelvin. When I visited =
Glasgow and gave my lecture to James Hough=1B$B!G=1B(Bs group there (=1B$B!=
H=1B(BInstitute for Gravitational Research=1B$B!I=1B(B), one of the first t=
hings I noticed was that the physics building is named after Kelvin. =
There is a legacy there which I wish were universal, but sadly it is not.&n=
bsp; Prof. Hough, who was made a Fellow of the Royal Society in 2003, is co=
mmitted to the same lofty goal as Thorne and troops at LIGO; i.e., be the f=
irst to actually see and measure gravitational waves. I was especiall=
y impressed by his specific invitation to his elderly =1B$B!F=1B(Bretired=
=1B$B!G=1B(B physics mentor to come give an opinion on what I had to say.&n=
bsp; I have never been blessed more than by the positive feedback I receive=
d from this man. It tells me that Hough appreciates more than just kn=
owledge; he has great respect for the wisdom that comes only from having ap=
plied that knowledge to practical systems.
There are some interesting quotes by o=
ther famous men that I think we should keep in mind while trying to extract=
understanding from the complexities of defect structures that have been se=
en, yet hardly studied in the way they need to be. Rutherford said,
=1B$B!H=1B(BAll of physics is either impossible or trivia=
l. It is impossible until you understand it, and then it becomes trivial=1B=
$B!I=1B(B.
And perhaps we should all stri=
ve not to fall (for reason of vested interests) into a trap of type that Ei=
nstein talked about,
"Only two things are ce=
rtain: the universe and human stupidity; and I=1B$B!l=1B(Bm not certain abo=
ut the universe."
&nbs=
p; It is not commonly known of Kelvin=1B$B!G=1B(Bs interest in s=
ome of the same problems we=1B$B!G=1B(Bve been discussing. He was the=
first, with his helper George Darwin (son of the famous Charles) to look a=
t the perplexing diurnal swing of a simple gravitationally restored pendulu=
m. Kelvin first did so by hanging a mass where it could swing in one =
of the sturdy stone doorways of the physics building. He was fascinat=
ed by the surprisingly complicated motions that he observed; so he and Geor=
ge created some elegant experimental techniques for monitoring such a pendu=
lum long term over a wide dynamic range. What they found proved beyon=
d their resources capability to properly understand for modelling purposes.=
The&n=
bsp; research that got me into much of the present business had its genesis=
in Kelvin/Darwin=1B$B!G=1B(Bs studies. In the last decade NASA scien=
tist Jim Shirley asked me to try and verify a postulate of his. Becau=
se each of the Earth and moon moves about their barycenter (displaced 80 pe=
rcent of the radius of the earth from its center), he expected we could mea=
sure a =1B$B!F=1B(Bredistributive force=1B$B!G=1B(B associated with the moo=
n=1B$B!G=1B(Bs =1B$B!F=1B(Bwhipping=1B$B!G=1B(B the earth around in a circl=
e with a period of one month.
=
I wouldn=1B$B!G=1B(Bt be surprised if Kelvin had th=
oughts about this possibility, although we couldn=1B$B!G=1B(Bt find specifi=
cs to prove this was so. Whereas he and Darwin were unable to bring c=
losure to their efforts for reason of their lack of an adequate tool (my, w=
hat he could have done with computers like we have today!), I haven=1B$B!G=
=1B(Bt been able to bring closure for reason of my stupidity, as compared t=
o the genius of Kelvin (I learned while there that he enrolled conditionall=
y at Glsogow as a young teen, and no doubt was =1B$B!F=1B(Bteaching his tea=
chers=1B$B!G=1B(B before being awarded his first degree).
I want to close these comment=
s with something else, for which I have been like =1B$B!H=1B(Bthe voice of =
one crying in the wilderness=1B$B!G=1B(B. I believe, in the same spir=
it that motivated Kelvin to try and wrest understanding from experiment con=
cerning the =1B$B!F=1B(Bbigger picture=1B$B!G=1B(B, that we should be doing=
something that (in my opinion) =1B$B!F=1B(Bcries out=1B$B!G=1B(B to be stu=
died. It has to do with the total power of seismic type that can be q=
uantified with our instruments. If you have your units right, then it=
is a straightforward matter to get these total seismic power numbers by si=
mply integrating the power spectral density over its full frequency range (=
the result being the maximum of my cumulative spectrum)—and then mult=
iply your result by the mass of the earth (if you are clever enough to fact=
or in a meaningful estimate for the frequency dependence for the Q of the e=
arth). Why multiply by the mass of the earth? Duh? =
Because what you are measuring is power in watts per kg. The same W/k=
g that your instrument measures, is by the application of Newton=1B$B!G=1B(=
Bs third law, the W/kg with which the earth is causing your instrument to u=
ndergo accelerations over a broad frequency range. (Kelvin would say =
=1B$B!F=1B(Byea and amen=1B$B!G=1B(B; why have you taken so long to bring t=
rivial understanding to a profoundly important question.)
So why is the total pow=
er of any importance? I talked with hurricane expert Kerry Emanuel ab=
out this and told him I was surprised by something. My estimates by t=
his means (using Jon Berger=1B$B!G=1B(Bs data) of the total seismic power (=
energy in the solid part of the earth) is a bigger fraction of the tidal po=
wer (braking of the earth=1B$B!G=1B(Bs rotation, easily and routinely estim=
ated) than I thought it should be. In other words, I thought more of =
the tidal power ought to be associated with waves of the oceans as opposed =
to vibrations of the crust. Kerry was fascinated with these thoughts,=
as he said =1B$B!H=1B(Bbecause there are some long-standing unsolved probl=
ems involving oceanic flows (and their model=1B$B!G=1B(Bs inability to desc=
ribe what is seen).
&nb=
sp; Keep up your good work, Brett.
Ra=
ndall
=