> I definitely agree with your analysis that Delta-T is surely also
> related to the movement of the inner core of the Earth - it makes
> perfect sense. However, what causes changes in the movement of that
> inner core? - for example, the movement of the magnetic poles as one
> reflection of that movement.

As I said before, we know very little about the Earth's interior, so
the answer must be "we don't know". However, we do know some things.
First, there's a temperature gradient within the Earth: the closer to
the Earth's center we get, the higher the temperature will be. At
the center of the Earth the temperature is believed to be
approximately the same as on the surface of the Sun. This
temperature gradient ought to cause a (very slow) convection in the
matter of the interior of the Earth. This, combined with the Earth's
rotation can cause a very complex circulation pattern inside the
Earth. And any inhomogenities in the matter inside the Earth will
make the circulation even more complex.

> I definitely think that the forces are - and have to be - external,
> since the Earth is a part of the solar system and does not simply
> spin around in space on its own.

You think so? Well, that means you also think that if these external
forces would be absent (or negligibly small), then the matter inside
the Earth would not move at all, despite the temperature gradient
within the rotating Earth. So please explain why you believe such
conditions within the Earth would not start any movement of the
liquid or semi-liquid matter inside the Earth. If you want to
convince others than yourself, you need to be much more explicit than
merely saying "I think so".

If you boil a pot of water on your stove, you'll see a lot of
circulation within the water while it's boiling. Is that too due to
forces from other planets in the solar system, rather than due to the
heat from the stove? If you say "no", why wouldn't such a "no" also
apply to the Earth's interior?

> Obviously, the forces of the Sun and the Moon will be important,
> but since I view the solar system to be just like electrons around
> an atom,

It isn't. For instance, planets do not move in fixed prescribed
orbits like electrons in an atom do - planets can have any orbit
(check out the orbits of all the comets and asteroids - this will
provide many good examples of exotic orbits). And planets never
suddenly jump from one orbit to another, like electrons in an atom
do. Push on a planet and it'll have its orbit gradually changed -
the stronger the push, the larger the orbital change. Push on an
electron in an atom and nothing happens at first, until it suddenly
jumps to another orbit.

> the smaller elements may be just as important as the larger ones.

FYI: in an atom all electrons are equally large. There are no
"large" or "small" electrons....

> Saying that you think you knew what "cam" I come from just because I
> even mentioned astrology was a totally unnecessary cheap shot. Sure,
> most mainstream astronomers themselves would never have the courage
> to take the world astrology into their mouths. They more or less
> deny this part of their heritage.

Nonsense! Check out e.g. Sky and Telescope, which mentions astrology
a few times every year in the magazine. Usually it mentions astrology
in the context of the history of astronomy, and that's where it belongs.
Occasionally, it mentions astrology when advicing stargazers on how
to deal with contemporary astrologers -- it's unfortunate that this
is a problem but it's nevertheless a reality.

> The fact is, the history of astronomy is tightly bound with astrology

Yep - and that's where it belongs

> and even Kepler devised his laws primarily with astrology in mind.

Astronomers of centuries ago were frequently astrology believers,
that's true. Newton was probably the last great scientist who also
believed in astrology (although he was more interested in alchemy),
but already at his time scientists started to question astrology more
and more. Newton's pupil Halley did not believe in it, and sometimes
the two gentlemen had arguments about that.

There's a big difference between ancient scientists and contemporary
astrologers though. The ancient scientists did their best with the
(by today's standards) very meager knowledge they had at their
disposal. Modern astrologers ought to know better: they have a vast
body of knowledge (which Kepler and Newton couldn't even dream about)
available, but they choose to ignore it.

> As written at http://www.hps.cam.ac.uk/starry/keplerastrol.html
>
> "Kepler disdained astrologers who pandered to the tastes of the
> common man without knowledge of the abstract and general rules,

This is precisely what contemporary astrologers do!

> Kepler believed in astrology in the sense that he was convinced that
> planetary configurations physically and really affected humans as
> well as the weather on earth. He strove to unravel how and why that
> was the case and tried to put astrology on a surer f ooting, which
> resulted in the "On the more certain foundations of astrology
> (1601)". In "The Intervening Third Man, or a warning to theologians,
> physicians and philosophers (1610)", posing as a third man between
> the two extreme positions for and against a strology, Kepler
> advocated that a definite relationship between heavenly phenomena and
> earthly events could be established."

Kepler did his best at his time. But he was mostly wrong here. With
the exception of the Sun, the celestial bodies do not have any
noticeable influence on our weather. There's not even any noticeable
correlation between the Moon's phases and the weather.

> So, please do not engage in unnecessary cheap personal shots

Then please don't refer to astrology.... except in its proper context,
which is the history of astronomy.

> just because I refer to harmonic ideas of the astrologers. I am in
> very good company in thinking that earthly events may somehow be
> related to other bodies in our solar system, even though the
> mechanism is not known, can not currently be proven, and may indeed
> even be a Chimera. That does not keep me from using some ideas
> borrowed from people like Kepler.

You're of course free to think whatever you want. But if you want
to convince others than yourself, you should find convincing
correlations between earthly events and celestial bodies. Don't
be satisfied with "correlations" barely above the noise level
because such "correlations" are most probably due to chance.

So far there are few convincing correlation of this kind. One is the
correlation between the Sun's position in the sky and our seasons.
Another is the tides by the Sun and the Moon. In this case we also
know the physical mechanism behind them. (sometimes astrologers
argue: "humans are 75% water, therefore there are tides in the humans
as well as in the oceans". In principle this is correct, but the
tides in the humans are insignificant because humans are so small
compared to oceans. As an experiment, fill your bathtub with water
-- it'll contain more water than you do -- and let it be there for
several days. Do this on the new moon or full moon, when the tides
are strongest. Try to measure the tides in your bathtub - did you
find any?)


[ further musings on astrology snipped ]

> You allege that Pluto can have no effect by traditional
> gravitational theory,

I never said that! I said that Pluto's influence on the Earth's
rotation is negligible. Please note the difference between
'negligible' and 'zero' - they are not the same!

In some cases Pluto's gravitational influence is non-negligible, for
instance the motion of Charon (Pluto's moon) is quite noticeably
influenced by Pluto. Another possible case would be a comet
happening to pass close to Pluto and later close to Jupiter: the
passage of the comet close to Pluto will cause a small change in its
orbit, and this small change can me magnified many times as the comet
later pass close to Jupiter. So in this particular case, Pluto can
cause the comet to end up in a very different orbit.

However, the "sphere of influence" of Pluto is quite small: objects
must be quite close to Pluto to be noticeably influenced. Earth is
always very far from Pluto, therefore Pluto will not have any
significant direct effect on the Earth. But a comet passing close to
Pluto and later also close to Jupiter could perhaps collide with the
Earth! This is of couse extremely improbable but not impossible, and
in such a scenario, Pluto would indeed have a very significant effect
on mankind.

> but what about all of these other theories, where small influences
> have disproportionate effects because they influence slightly larger
> things, which influence larger things, which influence even larger
> things.

Now you speculate in chaos theory. Such speculations are popular
nowadays. And in a way they are quite 'safe': since chaotic systems
are hard or impossible to predict, you're probably safe from being
proved wrong in your speculations.... <g> Anyway, my scenario with
the comet above shows a possible although very improbable mechanism
by which mankind could be strongly affected by tiny distant Pluto.
So in a way you are right: these things CAN happen! However, now
we're talking about something quite different than changes in Delta-T
and if Pluto could cause these, as you originally suggested.

> Ultimatley, you have a large effect. If we have dam that
> withstands 20 feet of water or 240 inches, the 241st inch is
> by comparison negligible, but it causes the flood so that
> every additional inch, no matter how small,

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
?????????? Are some inches smaller than others, or what ????

> is important. Without the 239th inch, the 241st is is the 240th,
> and we have no flood.
>
> Pluto could be the 241st inch.

Still looking for that needle in the haystack?

One thing we can be quite sure of though regarding Delta-T: Pluto's
possible but negligible influence on that is much much much smaller
than 1/241 of the total change....

In your example with the dam, we could switch from inches to
nanometers instead. So the dam withstands 6096000000 nanometers of
water, and at the 6096000001'st nanometer the dam will flood. And
perhaps Pluto can be the cause of that final nanometer - you get the
idea? Well, we have some problems here -- one nanometer of water
will be only some 5-10 water molecules thick. And I think you agree
with me that even a very weak wind will cause water waves millions of
nanometers high. Not to mention roughness and small bumps in the dam
itself, which also is millions of nanometers, or more, in size.

So that small one nanometer influence by Pluto will be buried in
"noise" caused by much larger fluctiations (millions of nanometers)
of other kinds - fluctuations which cannot be avoided.

Perhaps this example give you a good idea of what "insignificant"
actually means. But remember that although one nanometer is an
extremely small size, it is still different from zero.

-------------------------------------------------------------------

I'll end this by making a quantitative estimate of how large a
tide Pluto could cause. You suggested one inch and I suggested
one nanometer. Which one is most right, you or me?

First, the tide by the Moon is approximately twice as large as the
tide by the Sun. When they add upp (happens every new moon and
full moon), the Sun's tidal contribution will be about 1/3 of
the total tide.

A tide in the open ocean is approx 0.5 meters high. In some places
of the world, local topography can magnify this tide, and the largest
tides evern observed on the Earth is some 10 meters high. Of this
the Moon contributes some 7 meters and the Sun some 3 meters.

Pluto's mass is about 1/1000 Earth masses while the Sun's mass is
about 333,000 Earth masses. Thus Pluto's mass is 330 million
times smaller than the Sun's mass.

Pluto is 40 times as distant as the Sun. Since the tidal force is
inversely proportional to the cube of the distance, this means
that the distance factor makes the tide from Pluto 64000 times weaker
compared to the tide from the Sun.

This means that the tide from Pluto is some 2E+13 times weaker than
the tide from the Sun.

The Sun can cause tides which sometimes are as tall as 3 meters,
which is 3E+9 nanometers. Since the tidal force from Pluto is 2E+13
times weaker, this means Pluto can cause tides which sometimes are as
large as 0.00015 nanometers!

Yep, that's approximately 1000 times smaller than the size of a
water molecule! It is some 10 times larger than the size of the
nuclei of the atoms within that molecule though.

This result confirms even more that the direct gravitational
influence by Pluto on the Earth is -- extremely insignificant!

And that dam of yours is now some 40640000000000 "Pluto tidal
heights" tall -- yep, that's approximately 41 trillion ....

This is a far cry from your suggested 241 "Pluto tidal heights" tall.
But if you make the dam 1/30 nanometer tall (i.e. about 1/3 of the
size of a water molecule), then it would become some 241 "Pluto tidal
heights" tall ---- otoh then the dam would become so small that
nobody would notice it. And even if you dragged out an electron
microscope to show your "dam", no-one would want to call it "a dam".

----------------------------------------------------------------
Paul Schlyter, Swedish Amateur Astronomer's Society (SAAF)
Grev Turegatan 40, S-114 38 Stockholm, SWEDEN
e-mail: pausch at saaf dot se
WWW: http://stjarnhimlen.se/