"Nav" wrote in message
...


Jeff Morris wrote:

OK, Nav, its clear you're not going to get this without some help. You keep
claiming the centrifugal force varies across the Earth. However, that is
not
the case. Your assumption is that the Earth is rotating around the E-M
barycenter, and that because that is offset from the Earth center, the
centrifugal force is unbalanced. (Or more precisely, you claim the "r" in
the
centrifugal force equation is different on the near and far sides of the
Earth.)


I think it's you that does not understand that the rotation force is
based on the lunar cycle -28 days!

However, if we remove the daily rotation,

Great idea -not based in reality of course.

We are looking for the dominant effect - the daily rotation is not a contributor
to that. There are a variety of effects we're ignoring.


the Earth does not move around the
barycenter quite like you think.

Like I think?

OK, as you claim.


Only the center of the Earth describes a
circle around the barycenter.

So the Earth does wobble (now you are getting really close to the whole
story -where harmonics of all the orbital periods give a complete
answer). Now, don't all points on the surface move similarly around the
barycenter

No. Only the center of the Earth revolves around the barycenter. Other points
on the Earth revolve around other points nearby. Stop arguing and just work it
out with a model. If you "wobble" a disk, all points wobble the same way.
You're claiming that some points describe small circles, and some point describe
large circles, but that clearly can't happen unless you rotate the disk.

and if they do, what is the difference in their orbital path
to that of a circle?

All paths are the same. That's my point - stop talking and wobble a plate on
the table without rotating it. All points on it trace the same circle. Hold a
pencil on each side and look at the circles they trace. They all have the same
radius, and therefore the same centrifugal force.

Now as I see it, from the math, the differential
gravity model takes no account of this, exploiting the idea that the
orbital motion of every point on the surface is perfectly circular
around the moon (thereby allowing a cancellation of the centrigal
component), a point that you seem to be having a bit of trouble grasping.


There is no need to grasp it. You entire argument is different points feel
different rotation. But they don't - all points on the Earth feel the same
centrifugal force.

But your argument fails another test: The centrifugal force is "fictional" -
it is just a convenience to simplify some problems. The only real force at play
here is gravity, so any alternate approach must yield the same answer as a
"gravity only" solution.

By the way, the differential gravity idea first came from Newton. It's
correct as far as it goes but the orbital mechanics of the Earth-Moon
pair are more complicated (as far as I've been able to read, Newton only
saw the free falling body aspect in his tidal proposal). The Devil _is_
in the details and you can't ignore the system rotation. This really is
my last post on this. If you still haven't got the idea then I really
can't make it any clearer and you'll just have to ponder why University
Departments of Oceanographics (and NOAA etc.) all say that THE TIDES ON
EARTH are due to the difference between centrifugal and gravity forces.

As I've said, it's very easy to find numerous sites that scoff at the NOAA site
you've mentioned, its regularly cited as "bad science." And I don't deny that
there are a handful of sites that "handwave" that centrifugal force is the cause
of the second bulge, but there are dozens that refute that in great detail.
And virtually every published text supports my view.

And you still haven't responded to the obvious flaws in the formula you
proposed. If the centrifugal force from the Moon is as you claim, why does your
math show that the Sun's contribution is only 1% of the Moon's? You when to
great pains to show the math, but when I showed it was bogus you got very quiet
on that front.