Errata ?

[Gary Redmond]

OK!
I enjoy a lively discussion. Perhaps that was my objective, rather than my original position regarding the direction and source of the force which causes the tides.

Each particle of each body "attracts" every other particle. The actual number of forces may be near infinity. If we assume both bodies to be emitting separate forces (which they do) not just one force between them (which the formula implies), then the total force between two bodies becomes the sum of the two (or vector sum) of the many individual forces.
Those two resultant forces are exactly equal in magnitude and exactly opposite in direction. Therefore they are calculated as if they were one force.
Because the two (or many) forces are calculated on different properties of the two bodies, and as there has always been discussion regarding the difference between the gravitational mass and the inertial mass, I'm wondering if we shouldn't assume a body to be both a gravitational and an inertial mass and be mindful of the separate forces.

Perhaps the formula for gravitational force could be rewritten to include those ideas.


Formula 1

Hopefully you can see how I've made the total force of gravity between two bodies proportionate to the sum of the two resultant forces, and then inverse to the single distance between them squared. What that does is change our presently accepted value of G = 6.6726e-11 using mks units to G = 3.3363e-11 using mks units.

The Physics book says 'that "attract" means that a body exerts a force on another body that is directed back to the first body along the line joining the two bodies'.
But, the law of gravity says that 'any two bodies "attract" each other'.
Therefore, there are separate forces exerted by each of the two bodies.

Gravity is not unlike russ_watters "skateboarders", IF BOTH PULL.
There is only one rope or line of force. The action and reaction to each force is equal and opposite.
When you talk about a tide on a celestial body, that body becomes the reference frame, and the force comes from within that body.
Yes it is true the other bodies are doing the same thing, it's just a matter of which one is the reference.

The Earth's oceans tides are caused when the Earth's oceans "attract" or gravitate towards the Moon and Sun. Those waters are the source of the gravitational force which moves them.


BTW
I have a copy of Newton's Principia (translation) here on the desk. Newton used the term "mutual attraction" more than once. He also stressed the fact that the force of gravity diminishes the farther away from the source you go.

And to perhaps clarify the direction he said this:

Mathematical Principles ( PRINCIPIA) by Isaac Newton

Book III

PROPOSITION 8. THEOREM 8
In two spheres gravitating each towards the other, if the matter in places on all sides round about and equidistant from the centres is similar, the weight of either sphere towards the other will be inversely as the square of the distance between their centres.

Please note where Newton said "each towards the other". This is my argument that the tides gravitate towards the Moon and Sun. Yes the Moon and Sun are cute and "attractive", but the tides gravitate or attract themselves to those other cute attractive bodies. Any body has the force of gravity and it uses that force to bootstrap or move itself unless it is restrained in some manner, such as the apple restrained by the tree.

Newton also said:

Book 3, Proposition 4. Theorem 4
That the moon gravitates toward the earth, and by the force of gravity is continually drawn off from a rectilinear motion, and retained in its orbit.

Can you see in that theorem that the moon "gravitates" or is the source of the gravitational force it bootstraps or causes itself to be moved or "drawn off"?

[informant]

Whoa!

If we assume both bodies to be emitting separate forces (which they do) not just one force between them (which the formula implies)[...]

What formula is that that you say implies only one force gravitational between two bodies?

[...]then the total force between two bodies becomes the sum of the two (or vector sum) of the many individual forces.

And why sum forces that act on different bodies?! :-?

[kilopi]

OK!
I enjoy a lively discussion. Perhaps that was my objective, rather than my original position regarding the direction and source of the force which causes the tides.

Perhaps so. Are you now saying that you're OK with Groliers and Encarta?

[Gary Redmond]

I am still convinced that the encyclopedias are wrong, perhaps even more than before.
When those books say the "Moon and Sun" or the "Sun and Moon" cause the tides, they have the direction of the force reversed.
I can see a train track from my window. Do we say the train pushes the engine, or the engine pulls the train? The body with the force always acts on the other body.

If encyclopedia were to say:
The oceans attract themselves to the Sun and Moon
The oceans pull themselves to the Sun and Moon
The Sun and Moon are pulled on by the oceans
The Sun and Moon are attracted by the oceans
Or in some other way indicate that the oceans are not passive, but take an active roll in causing the tides it would be OK.
I'm not sure why that concept should be so difficult to convey.

The formula F=GMn / r² implies only one force F between the two bodies M and m.
The Universal law of gravity clearly states that any "two" bodies in the universe "attract" each other.
The words 'attract each other' means, that M "attracts" m, and that m "attracts" M. That means that both bodies emit separate forces. That fact becomes even more evident when the law of superposition is applied to 3 or more bodies. In the case of multiple bodies each of the bodies exerts force on every other body.

If we have a four body problem involving the Earth, the Moon, the Sun, and the oceans, each of those 4 bodies "attract" or emit the force of gravity (particle by particle).

Newton said

Book 3, Proposition 4. Theorem 4
That the moon gravitates toward the earth, and by the force of gravity is continually drawn off from a rectilinear motion, and retained in its orbit.

Newton specified the "moon", but the same is true of the earth, the sun, and the oceans. If the oceans did not gravitate to the earth they would move off in a straight line "rectilinear motion". If the oceans did not gravitate to the sun and moon they would not accelerate horizontally and vertically, there would be no tides.

As before, "the Moon and Sun are cute and 'attractive', but the tides gravitate or "attract" themselves to those other cute attractive bodies."

[informant]

The formula F=GMn / r2 implies only one force F between the two bodies M and m.

No, it does not, Gary. There are two forces. That's Newton's Third Law of motion!
The formula gives the magnitude of each of the forces, which is the same. But the two forces are not the same. They have different senses, and apply to different bodies. Remember that forces are vectors.

[Cougar]

I'm not so sure I agree, Informant.

The words 'attract each other' means, that M "attracts" m, and that m "attracts" M. That means that both bodies emit separate forces. That fact becomes even more evident when the law of superposition is applied to 3 or more bodies. In the case of multiple bodies each of the bodies exerts force on every other body.

Well, that's the way I look at it, although this usage of the term "force" may not be technically correct. My main concern in this whole discussion is how to correctly construct a (newtonian) gravitational model. So I am only concerned with [step 1] what acceleration does mass A cause on every other mass of concern, [step 2] what acceleration does mass B cause on every other mass, [step 3] etc. During any one step, the acceleration that A causes depends only on the mass of A - not on the mass of any of the affected bodies.

Of course Nature does this in massively parallel fashion while I have to do it sequentially, but the results are good enough for me.

[Gary Redmond]

Remember that forces are vectors.

Vectors have direction.
As a vector the force of gravity has direction. The gravitational force of the ocean attracts the Moon, the Sun, and the Earth.
The direction to the Earth is a constant DOWN. The other two directions are constantly changing sometimes up, sometimes down, sometimes over lapping, but usually along some horizontal vectored sum.

In regards to Newton's Third Law, my Physics Book says:

Newton's third law of motion.
Whenever one body exerts a force on a second body, the second body always exerts an equal and opposite force on the first body.

That statement is somewhat inconsistent with what Newton said.

LAW III
To every action there is always opposed an equal reaction: or, the mutual actions of two bodies upon each other are always equal, and directed to contrary parts. Whatever draws or presses another is as much drawn or pressed by that other. If you press a stone with your finger, the finger is also pressed by the stone. If a horse draws a stone tied to a rope, the horse (if I may so say) will be equally drawn back towards the stone; for the distended rope, by the same endeavor to relax or unbend itself, will draw the horse as much towards the stone as it does the stone towards the horse, and will obstruct the progress of the one as much as it advances that of the other. If a body impinge upon another, and by its force change the motion of the other, that body also (because of the equality of the mutual pressure) will undergo an equal change, in its own motion, towards the contrary part. The changes made by these actions are equal, not in the velocities but in the motions of bodies; that is to say, if the bodies are not hindered by any other impediments. For, because the motions are equally changed, the changes of the velocities made towards contrary parts are inversely proportional to the bodies. This law takes place also in attractions, as will be proved in the next Scholium.

Note that Newton specified that "a body" impinges "upon another,".
He gave the single force ownership; a force belongs to one or the other, not both of the bodies.
He than specified "and by its force" (referring to the impinging body) changes the motion of the other body as well as its own.
Newton, did not miraculously give the other (acted upon) body a separate force as did my Physics book.
Yes, both bodies can have equal forces, and yes they can both apply those forces along the same "line of force". If they do, the resultant or vector sum of the two forces will fall along that same "line of force", and then may be considered as one force.
This of coarse is the case with gravity. Each body exerts or impinges its force (or forces) upon the other body. The forces are equal in magnitude and opposite in direction, each body acts, and each body reacts. The Earth and the Moon both have tides. Both tides are caused by equal and opposite forces. The Earth tides are caused when the Earth acts on the Moon. The Moon tides are caused when the Moon acts on the Earth.
Also note the Physics book for mathamatical calculations divides the single force in half, makes the halves equal, and then calls the one force two.

LA W II
The change of motion is proportional to the motive force impressed; and is made in the direction of the right line in which that force is impressed. If any force generates a motion, a double force will generate double the motion, a triple force triple the motion, whether that force be impressed altogether and at once, or gradually and successively. And this motion (being always directed the same way with the generating force), if the body moved before, is added to or subtracted from the former motion, according as they directly conspire with or are directly contrary to each other; or obliquely joined, when they are oblique, so as to produce a new motion compounded from the determination of both.

In that first sentence by Newton it says a "change of motion" "is made in the direction" "in which that force is impressed."

The oceans' tides "change of motion", is “in the direction” of the Sun and Moon.
Therefore the force is from the oceans toward the Moon and Sun.

The Sun and Moon do not cause the tides as the encyclopedias say, the oceans cause their own tides.

[Eroica]

It is true that Newton, in his statement of the Third Law, does not specifically say that when Body A exerts a force upon Body B, Body B exerts an equal and opposite force upon A. But he does say that A will undergo a change of momentum equal in magnitude but opposite in direction to the change of momentum it causes in B. (Note: Newton says motion, but it's clear that he's speaking of what we know as momentum.)

Now, in the Second Law he does say that a change of momentum "is proportional to the motive force impressed." So he does at least imply that a motive force is impressed on A, even if he doesn't say it in so many words. Are you saying that you believe that both these forces - the action, which acts on B, and the reaction, which acts on A - are exerted by A?

[SeanF]

In that first sentence by Newton it says a "change of motion" "is made in the direction" "in which that force is impressed."

The oceans' tides "change of motion", is “in the direction” of the Sun and Moon.
Therefore the force is from the oceans toward the Moon and Sun.

The Sun and Moon do not cause the tides as the encyclopedias say, the oceans cause their own tides.

So when I hold my magnetic screwdriver over the screw I dropped on the floor, and the screw "jumps" up onto the screwdriver, it is therefore incorrect to say that the screwdriver attracted the screw, I have to say that the screw attracted itself to the driver?

[informant]

I agree with the two posters above. And let me add some comments:

Note that Newton specified that "a body" impinges "upon another,".
He gave the single force ownership; a force belongs to one or the other, not both of the bodies.

It seems to me that it’s this whole notion of a force “belonging” to a body which you are misunderstanding. A force is exerted by a body on another body, but the value of the force can depend on the characteristics of both bodies. In the specific case of gravity, you have two forces, one on each body, each of the same magnitude (but not mathematically equal because they have opposite direction).
It’s natural to interpret this saying that the Earth causes a force on the Moon, and the Moon causes a force on Earth, but the magnitude of each force is determined by the mass of the body on which the force is exerted, the distance between the two bodies, and the mass of the body which exerts the force. It’s in this sense that I say that each force is a property of (i.e. is dependent on) both bodies.

Yes, both bodies can have equal forces, and yes they can both apply those forces along the same "line of force". If they do, the resultant or vector sum of the two forces will fall along that same "line of force", and then may be considered as one force.

Mathematically, yes, you can do that – and notice that the two forces add to the zero vector, as they must, in virtue of Newton's Third Law.
Physically, however, it’s only meaningful to speak of a resultant when you’re talking about a set of forces which act on the same body. But the two forces you’re talking about do not act on the same body; one acts on the Earth, and the other on the Moon!

I went back and realised that your original point was about tides:

If the oceans had no mass there would be no tides.
The tides exist only because the oceans have mass and gravity. Because they have mass and gravity they attract or pull themselves horizontally toward the Moon and the Sun. It is the horizontal accelerations, which cause the tides to pile up.

Am I correct?

If the oceans had no mass, there would be no tides, true.
But if there were no Moon, then there would be no tides either, even if the oceans had mass.
So the mass of the oceans is not enough to explain tides.

The Earth tides are caused when the Earth acts on the Moon. The Moon tides are caused when the Moon acts on the Earth.

I would have said it the other way around: the Moon tides are caused by the action of the Earth on the Moon, and the Earth tides are caused by the action of the Moon on the Earth.
But even this is an over simplification. In effect, tides are not caused by a force, rather by a force differential. See what the BA has to say about it:

Now we see that in this sense, the Earth is stretched by the difference in the Moon's gravity across the Earth. We call this effect "tides". Tides are a differential force, that is, they result by the difference in the force of gravity between two points.

http://www.badastronomy.com/bad/misc/tides.html

The force differential exists because:
1) There is a force, exerted by the Moon.
and
2) The Earth is large enough for the effect of the force differential to be noticeable.

You need the Earth and the Moon to explain tides.

[Eroica]

If the oceans had no mass there would be no tides. The tides exist only because the oceans have mass and gravity. Because they have mass and gravity they attract or pull themselves horizontally toward the Moon and the Sun. It is the horizontal accelerations, which cause the tides to pile up.

Am I correct?

No. If you were then it would follow that nothing that is massless and exerts no gravitational attraction of its own could ever be affected by gravity. But photons are massless, they exert no gravitational attraction of their own, and yet they are subject to gravity just like the oceans. They are bent when they pass close to a massive body like the Sun, and can't even escape from a black hole.

Are you saying that as they pass the Sun, photons pull themselves towards it?

[kilopi]

But photons are massless, they exert no gravitational attraction of their own, and yet they are subject to gravity just like the oceans.

I dunno. Photons would have to exert gravitational attraction of their own--at least in this context, where we're not treating gravity as a "fictitious" force.

[Eroica]

In that case, I stand corrected. Ignore my previous post.

[Gary Redmond]

If a vehicle accelerates to or from a stop, does the engine and brakes belong to the vehicle or do they belong to the road?
When a vehicle accelerates one way the earth goes the other. That is the action reaction, but the source of the force is what I'm after. Where is the engine, where are the brakes? What is the "cause"?
(Key word "cause")

WE KNOW THIS
The ocean has mass.
Mass has the force of gravity.
The force of gravity attracts.
Therefore the ocean attracts.
Question, where does the force or “cause” of the oceans tides come from?
The tides move because of what?
If the tides are described as a movement of the oceans both horizontally and vertically relative to the Earth, the Moon and Sun aren't even in the equation.
The encyclopedia says or infers that, the Moon and Sun are the “cause“.
(Key word "cause")

It is unfortunate for this argument that the objects which the oceans attract also have the same property of gravity. Perhaps the one thing which is most convincing is the direction of the force.

LAW II
The change of motion is proportional to the motive force impressed; and is made in the direction of the right line in which that force is impressed.

The tides appear to follow or change their motion in a vectored direction not a divided direction to the Moon and Sun. If the Moon and Sun pulled separately the oceans particles would be divided there would most often be 4 tides not two. So I feel that the source of the force must be the oceans and the vectored line which each of the oceans’ particles follow is towards the "luminaries" as Newton called the Moon and Sun.

SeanF used a magnetized screwdriver to pick up a screw. What if the screw were made of plastic, copper, aluminum, or gold, would the screwdriver have any less magnetic force, of course not, it just wouldn't pick up the mass of the nonferrous screw.
For imaginary purposes set aside the fact that the Moon and Sun have the force of gravity. Assume that they only have a mass to which the ocean attracts itself. (Like Eroica's photon) Would the Earth still have tides?
I say yes.
If the Moon and Sun had no gravitational force with which to attract the tides, could you say they were the "cause"?
I don't think so; without the force you can’t have a "cause".
The oceans attract themselves to the Moon and Sun, therefore the oceans are the "cause" of the tides, or at the least, the force they possess is the “cause“. The Sun and Moon are simply inertial hitching posts to which they are tied.

[informant]

One cannot attract oneself. It's unnatural.

[kilopi]

If a vehicle accelerates to or from a stop, does the engine and brakes belong to the vehicle or do they belong to the road?

Except for Fred Flintstone's, I'm pretty sure the engine and brakes belong to the vehicle.

WE KNOW THIS
The ocean has mass.
Mass has the force of gravity.
The force of gravity attracts.
Therefore the ocean attracts.
Question, where does the force or “cause” of the oceans tides come from?

Ultimately, that's the ultimate question

I don't think so; without the force you can’t have a "cause".
The oceans attract themselves to the Moon and Sun, therefore the oceans are the "cause" of the tides, or at the least, the force they possess is the “cause“. The Sun and Moon are simply inertial hitching posts to which they are tied.

That's just a quibble over nomenclature--you can't say that the encyclopedias are wrong, though. In the context of newtonian gravity, they are correct.

[Gary Redmond]

One cannot attract oneself. It's unnatural.

Does that mean my car can't go down the road, because the engine isn't in the Earth? (Like the Cable Cars)

The ocean has the property of gravitational force.
The oceans attract the Moon and Sun.
The Moon and Sun have more inertial mass than the oceans.
The oceans can't pull the luminaries to them, so they pull themselves to the luminaries.
Thus they attract themselves.

That's just a quibble over nomenclature-

Are you saying that I'm correct, but that I shouldn't quibble about it?

-you can't say that the encyclopedias are wrong, though. In the context of newtonian gravity, they are correct.

Hum? I don't understand.
The universal law of gravity (attributed to Newton) always indicates that every particle in the known universe has the force of gravity. (Newton used the word "corpuscle" rather than particle.)
Having the force of gravity means that particles attract. (Newton explained how the "corpuscle" attracts to a large mass, as if the large mass were all at its "centre".)
Attract means to pull.
This is where it gets complicated, for a particle to pull it must have something to pull on or against. If there are two or more particles, those particles pull on or attract each other.
The oceans "corpuscles" pull on or attract the "centre" of the Moon and Sun.
Because the Moon and Sun have inertia and because they are trying to go off in a straight line the oceans can't retrieve them. Therefore the oceans pull themselves both horizontally and vertically towards the Moon and Sun (one "corpuscle" at a time).

I've said it before I'll say it again. The encyclopedias are wrong; they have the direction of the force that causes the tides backwards. It is the oceans gravitational attraction to the Moon and Sun, not the gravitational attraction of the Moon and Sun, which causes the tides.

[kilopi]

That's just a quibble over nomenclature-

Are you saying that I'm correct, but that I shouldn't quibble about it?

No, you are wrong when you say that the encyclopedias are incorrect.

-you can't say that the encyclopedias are wrong, though. In the context of newtonian gravity, they are correct.

Hum? I don't understand.

You are looking at it from a different perspective. Your point of view does not change the point of view for others.

[informant]

One cannot attract oneself. It's unnatural.

Does that mean my car can't go down the road, because the engine isn't in the Earth? (Like the Cable Cars)

No, and I fail to see the analogy.

The ocean has the property of gravitational force.
The oceans attract the Moon and Sun.
The Moon and Sun have more inertial mass than the oceans.
The oceans can't pull the luminaries to them, so they pull themselves to the luminaries.

Why do you say that the oceans can't pull the luminaries to them?!

Edited.

[Gary Redmond]

No, you are wrong when you say that the encyclopedias are incorrect.

I have always thought that the source of the force was the cause of an action-reaction. Now you tell me I'm wrong?

You are looking at it from a different perspective. Your point of view does not change the point of view for others.

OK, so my perspective is correct, just different.
When I say:
The oceans have mass.
Mass emits the force of gravity.
Gravity attracts.
The oceans attract the Sun and Moon.
The Sun and Moon have greater inertial mass than the oceans.
Therefore the oceans during their effort to attract the Moon and Sun attract themselves towards those bodies causing the tides.

I fail to see the analogy.

My car goes down the road (any road) because it has an engine (source of force).
Rockets go to the Moon (and beyond) because they have an engine (source of force).
The tides move in/out up/down (any where) because they have gravity (source of force).
The Cable Car is connected to a cable the (source of force) in the Earth. Its range of (motion is very limited) it only goes where the cable goes. It doesn't really have a force of its own. When the encyclopedias say the Moon causes the tides it removes the force from the oceans and gives it to the Moon.

"The oceans can and do pull the luminaries to them."
OR
“Why do you say that the oceans can’t pull the luminaries to them?!”

When I jump up and down; the Earth moves in the opposite direction. I understand.
AND
"Newtons" first law says, once put in motion a body stays in motion in a straight line.
Because of this wonderful thing called gravity, none of the three bodies we're talking about can do that straight line thing. So they are forced to rotate, the acceleration of rotation equals the acceleration of gravity. Thus the masses in their entireties can't move to or fro, they can only be distorted.
Einstein said: "In gravitational fields there are no such things as rigid bodies with Euclidean properties". The tides are very non-rigid.

[kilopi]

No, you are wrong when you say that the encyclopedias are incorrect.

I have always thought that the source of the force was the cause of an action-reaction. Now you tell me I'm wrong?

You are wrong when you say that the encyclopedias are wrong.

The Cable Car is connected to a cable the (source of force) in the Earth. Its range of (motion is very limited) it only goes where the cable goes. It doesn't really have a force of its own. When the encyclopedias say the Moon causes the tides it removes the force from the oceans and gives it to the Moon.

That's your interpretation. However, notice, that as far as the tides are concerned, the ocean only goes where the moon or sun go--so the oceans are like cable cars!

Because of this wonderful thing called gravity, none of the three bodies we're talking about can do that straight line thing. So they are forced to rotate, the acceleration of rotation equals the acceleration of gravity.

Are you really claiming that the acceleration of the rotation of the Earth equals the the acceleration of gravity? On the Earth's surface? They differ by a few orders of magnitude. Or, do you mean something else? What would that be?

[informant]

My car goes down the road (any road) because it has an engine (source of force).

Actually, that isn’t enough. Put a car with an engine on a road with zero friction, and it will not move.

I Rockets go to the Moon (and beyond) because they have an engine (source of force).

Rockets have an engine?! Are you sure?

The tides move in/out up/down (any where) because they have gravity (source of force).

“Tides” are an abstract concept, not an object. I think you mean that the oceans have mass, right?
I hope you don’t mind that I nitpick like this, but it’s very important that we use the proper terms, to be sure that we don’t confuse different concepts.

"The oceans can and do pull the luminaries to them."
OR
“Why do you say that the oceans can’t pull the luminaries to them?!”

"Newtons" first law says, once put in motion a body stays in motion in a straight line.
Because of this wonderful thing called gravity, none of the three bodies we're talking about can do that straight line thing. So they are forced to rotate, the acceleration of rotation equals the acceleration of gravity.

Terminology alert again! I think you’re talking about why planets revolve around other bodies, not why they rotate.
And gravity is not the reason for revolution per se. You also need velocity.

[Gary Redmond]

You are wrong when you say that the encyclopedias are wrong.

OK, I'm quite certain they are, but I'll try to not say it again if that will help you decide for yourself.

That's your interpretation. However, notice, that as far as the tides are concerned, the ocean only goes where the moon or sun go--so the oceans are like cable cars!

Yes and No, the container of sneakers that was dumped in the Aleutian’s washed ashore in WA, OR, CA, and elsewhere. Those shoes had thousands of miles of free motion; they didn't all come down to the same place or at the same time. Sneakers also attract themselves to the Moon and Sun. If the Cable Car becomes disconnected it can't reconnect. If a sneaker ran aground quite often it could reconnect itself next high tide.

Are you really claiming that the acceleration of the rotation of the Earth equals the acceleration of gravity? On the Earth's surface? They differ by a few orders of magnitude. Or, do you mean something else? What would that be?

What I meant was:
The Earth and Moon revolve around their barycenter. The gravitational "attractions" between them is the centripetal force which keeps them together. The outward acceleration (try to go in a straight line) of that rotation is equal to the "attractions" between them.
Note: I've made the force between them plural.
Earth particles attract Moon particles, Moon particles attract Earth particles, all the particles of both bodies possess the force of gravity, and the total force equals the vector sum of the forces.

Actually, that isn’t enough. Put a car with an engine on a road with zero friction, and it will not move.
Rockets have an engine?! Are you sure?

Actually in both of the above the fuel and oxidizer are the source of force. Without the friction the direction of the cars exhaust pipe will push like a jet engine. Solid fuel rockets have some sort of nozzle or engine.

“Tides” are an abstract concept, not an object. I think you mean that the oceans have mass, right?
I hope you don’t mind that I nitpick like this, but it’s very important that we use the proper terms, to be sure that we don’t confuse different concepts.

CORRECT. Thank you. I had said the oceans mass several times before, I just got sloppy. I have tried to edit carefully, but sometimes I have to be human.
I have found several places in this book of Newton's where he does similar things. He too was human.

Terminology alert again! I think you’re talking about why planets revolve around other bodies, not why they rotate.
And gravity is not the reason for revolution per se. You also need velocity.

Once again I just got sloppy. Sorry!
When I said "stays in motion in a straight line“, I was trying to infer that the three bodies Earth, Sun, and Moon were in some way trying to move away from each other at some relative to something velocity.
I have rotated things all my life; it is hard to remember that things revolve without my help.

The Earth and Moon attract each other.
The Earth attracts the Moon.
The Moon attracts the Earth.
The Earth's oceans (or a sneaker) attract the Moon.
The Moon's mare (rocks) attract the Earth.

When Newton explained how a "corpuscle" attracted a large body or mass of particles, the resultant of all the separate forces made the large mass become a single point or the center of gravity of the mass.
So the sneaker doesn't particularly attract a Moon-rock. Nor does a Moon-rock attract the sneaker. The sneaker does however attract the Moon's center of gravity, as does the Moon-rock the Earth's center of gravity. The individual particles of one body attract the whole of the other.

[Tensor]

Isn't trying to use Newton's laws to describe the tides rather moot? Since General Relativity describes the tides (in simple terms) as a stretch of spacetime in the direction of the moon or sun and a squeeze at 90 degree angles to that direction? No "force" is required.

[kilopi]

Isn't trying to use Newton's laws to describe the tides rather moot? Since General Relativity describes the tides (in simple terms) as a stretch of spacetime in the direction of the moon or sun and a squeeze at 90 degree angles to that direction? No "force" is required.

It's a fictional force, but it's a force nonetheless. It's certainly as real as centrifictional force.

[Gary Redmond]

It appears that this subject matter was discussed by Newton over 300 years ago.

Book I
PROPOSITION 61. THEOREM 24
If two bodies attracting each other with any kind of forces, and not otherwise agitated or obstructed, are moved in any manner whatsoever, those motions will be the same as if they did not at all attract each other, but were both attracted with the Same forces by a third body placed in their common centre of gravity; and the law of the attracting forces will be the same in respect of the distance of the bodies from the common centre, as in respect of the distance between the two bodies. For those forces with which the bodies attract each other, by tending to the bodies, tend also to the common centre of gravity lying directly between them; and therefore are the same as if they proceeded from an intermediate body. Q.E.D.

The "Tides" are not caused by the Moon and/or Sun as is most often claimed.

The "Tides" are caused by their own gravitational force, which

"by tending to the bodies, tend also to the common centre of gravity lying directly between them; and therefore are the same as if they proceeded from an intermediate body."

[kilopi]

You are wrong when you say that the encyclopedias are wrong.

OK, I'm quite certain they are, but I'll try to not say it again if that will help you decide for yourself.

I have decided, for myself, that one can accept a point of view such that one can say that the encyclopedias are wrong, but then one also has to say that you are wrong too.

[Musashi]

The "Tides" are not caused by the Moon and/or Sun as is most often claimed.

The "Tides" are caused by their own gravitational force, which

I would say that, if the first statement is true, than the second statement is false. It seems that the tides are caused by the attraction between the oceans and the Moon and/or Sun. Not one or the other.

If two bodies attracting each other with ...

[Gary Redmond]

Tensor Thank You.
This has come up more than once, and I believe it needs to be worked on.

"General Relativity describes the tides (in simple terms) as a stretch of spacetime in the direction of the moon or sun and a squeeze at 90 degree angles to that direction"

Questions:
An effect such as the tides must require a cause?
If no "force" is required, what is the cause?
Is it my understanding that the stretch you discribe comes from the gravitational mass of the oceans and is directed toward the "moon or sun"?
The "90 degree squeeze", is that like a rubber band constricting a cone?
Do you have a source for the squeeze other than perhaps the Earth's own constricting mass?
That would make it more of a squirt than a squeeze would it not?

It has been my position since my first post using the Newtonian Law of gravity that the direction of the force is from a mass (the oceans) toward some mid point in the direction of a second mass (moon or sun) or towards the center of the second mass (moon or sun).

The encyclopedias credit the secondary masses as being the cause of the tidal motions.
I still say that the tides are caused by the Earth and Earth's oceans, not the bodies to which they attract. It shouldn't matter whether gravity is a force, or if it just warps spacetime. It is the source of the gravity, which is the cause of the tides whether that gravity is a force or not.

[kilopi]

Do you have a source for the squeeze other than perhaps the Earth's own constricting mass?

Are we still talking tides? Then, yes, the tides provide the "squeeze" as well as the "squirt."

It has been my position since my first post using the Newtonian Law of gravity that the direction of the force is from a mass (the oceans) toward some mid point in the direction of a second mass (moon or sun) or towards the center of the second mass (moon or sun).

That could be a problem. In general, that's not true, even in Newtonian mechanics. It's only true for spherically symmetric bodies.

I still say that the tides are caused by the Earth and Earth's oceans, not the bodies to which they attract.

So, you're saying that the Earth can attract the water, but the Sun and Moon can't? That's being inconsistent, on your part.