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From the World Book Encyclopedia copyrighted in 1938: 'The sun pulls the earth with 175 times the force that the moon does.'

In order for physicists to account for the Newton Theory that says the moon pulls the earth with twice the force that the sun does, there is their explanation in the Americana Encyclopedia, page 613 in Volume 27 under 'TIDES' that was copyrighted in 1965.

'A slight modification to Newton's law occurs in the mathematics of this problem."

If you change the pull of the sun from 175 times greater than the pull of the moon mathematically, to end up saying the pull of the sun is only HALF as much as the moon and call that a 'slight modification'.

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At Calumet, Michigan, in 1901 they took two piano wires 4,250 feet long plumb bobs attached and dropped them down two mine shafts 4,250 feet apart. They expected the pull of gravity, which is supposed to be in the center of the earth, to pull these two plumb bobs closer together. Much to their surprise they found out the wires at the bottom WERE FURTHER APART than they were at the top. This led them to believe that: 'Maybe there is no such thing as MASS ATTRACTION.'

It is just something else to consider really. Main question is about the bridge WITHOUT Wrights' theory.

Because we're so used to instability, and massive weigh burying into the ground, and distance, it's all too easy to dismiss an endless bridge. I like the length of pipe idea, it makes sense! Whatever it weighs is all that will be pushing into it! There's nothing sideways except for wind. - Gravity pulls down, not sideways. That weight is all evenly distributed into the entire length of tubing.
There's no weight sideways until the tubing actually meets and joins up. The
weight is all evenly distributed. There's nothing there but its own self weight! It IS all about gravity, but there's not as much as we think. - Not in an endless bridge anyway! - Endless tower? - No way!

Dave.

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Originally posted by davidratcliff6255:
STAii, I only 'slightly' understand the rest of Wrights' theory. The only part that REALLY interests me is this section:

At Calumet, Michigan, in 1901 they took two piano wires 4,250 feet long plumb bobs attached and dropped them down two mine shafts 4,250 feet apart. They expected the pull of gravity, which is supposed to be in the center of the earth, to pull these two plumb bobs closer together. Much to their surprise they found out the wires at the bottom WERE FURTHER APART than they were at the top. This led them to believe that: 'Maybe there is no such thing as MASS ATTRACTION.'

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Orbital bridge? This was advocated in A C Clarke's Fountains of Paradise, along with the idea of the space elevator. The patent is already taken. Possible? Maybe. We would require materials extremely strong under compression. We also need it to be insulated so that as it cuts through the earth's magnetic field, we don't get annoying currents flowing through it. It would be a huge proccess, and any slight instability or disturbance would be disastrous. Constant bombardment by cosmic waves will damage the structure, as well as the large amounts of space junk we have. Until the bridge is constructed fully, it would be extremely unstable. So bad idea -> not worth it.

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Originally posted by FZ:
We would require materials extremely strong under compression. We also need it to be insulated so that as it cuts through the earth's magnetic field, we don't get annoying currents flowing through it.

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not worth it

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You would also need very strong in tension yet lightweight material for the lift to reach the orbital bridge/ring.

From earlier discussion:
________________________________________________________________
If you had a self supporting steel ring around the equator, and provided
it with full restraint against buckling, the stress in the steel would be
around 56,000ksi (the math is simple: stress=pressure*radius/thickness).
This is about 500 times greater strength than is presently available on the
market.
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The argument about steel having to be 500 (others say 1,000) times stronger than present does not ring true to me! For example: Hold up a length of hollow tubing, e.g. 300 mm x 50 mm. There is of course NO lateral pressure apart from wind - only gravity. The total weight of the length of tubing is all that will be pressing into itself when it joins as the two ends meet. The weight, which is surprisingly very little (I say little on a grand scale), would also be evenly distributed around the entire ring....Same as in the smaller length.

Provided that you could supply full restraint, a steel tower could be built to arould 3.5 km (uniform section - 6 km tapered) A bridge, having two ends to support the weight instead of only one in a tower, then equates to a span of around 7 km (self weight only). We could not go to say 20 km as the weight has to go somewhere. But what about around the entire planet?
Because we're so used to instability, and massive weigh burying into the ground - and distance, it's all too easy to dismiss an endless bridge.

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Keep in mind that steel has a yield stress of ~200MPa. The trusses will simply collapse in on themselves from the excessive compression. The truss itself would need to support it's own weight, and that weight would just be enormous.

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Comments on this thread:

1) You say for arguments sake 10m off the ground. This is impossible. There isn't a single path on the earth which is 10m or less off of sea level the entire way around the circumference. This device MUST be at a uniform altitude from the center of gravity or you will have unbalanced gravitational force causing it to collapse.

2) You say that this device will be "light". No, sorry. Steel is enormously heavy. ~8gm/cm³

3) The reason why the steel needs to be stronger is not something which can be swept under the rug. It's not just a matter of "supporting" its own weight up. It needs to hold the weight of all the other steel "out".

Assume you have your piece of hollow steel tubing in a ring around the earth. Assume you then chop a 1m piece out of it (we'll call it 12 noon to illustrate). Look at the remaining (nearly circular) arc. Every single mm of that arc which is on the 12 - 6 side is getting gravitationally attracted to the left side of the circle. Every single mm of the arc which is on the 6-12 side is getting attracted to the right side. Now the parts closer to the cut will not contribute much to that since their gravity is pulling them 'down' toward the center, and the parts at the 6 side won't contribute much either, since their gravity is pulling them 'up' toward the center. The rest of it does contribute though... a LOT. That force creates an enormous stress which gets transmitted throughout the entire length of the pipe. The pipe will be over 36000 km long. It doesn't just support itself simply by dividing it evenly... the combined force is supported axially by the ENTIRE pipe. 36000km at 8gm/cm³

enigma

1) You say for arguments sake 10m off the ground. This is impossible. There isn't a single path on the earth which is 10m or less off of sea level the entire way around the circumference. This device MUST be at a uniform altitude from the center of gravity or you will have unbalanced gravitational force causing it to collapse.
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For arguments sake (hypothetically) 10m above the ground (could be ground level at the top of Mt. Everest actually) Wouldn’t matter if it were 100m or 500m as there’s very little difference in the gravity at those variances anyway.
Would be suitably anchored to the ground by cables all around the circumference, so shouldn’t matter if it were off centre to gravity.

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2) You say that this device will be "light". No, sorry. Steel is enormously heavy. ~8gm/cm3

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Very light compared to what you would expect! - The steel tubing would only have to be around 2m in diameter, with walls about 20mm thick. There would be three, possibly four, tubes side by side to give better lateral stability. (Same as for towers)

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3) The reason why the steel needs to be stronger is not something which can be swept under the rug. It's not just a matter of "supporting" its own weight up. It needs to hold the weight of all the other steel "out".
Assume you have your piece of hollow steel tubing in a ring around the earth. Assume you then chop a 1m piece out of it (we'll call it 12 noon to illustrate). Look at the remaining (nearly circular) arc. Every single mm of that arc which is on the 12 - 6 side is getting gravitationally attracted to the left side of the circle. Every single mm of the arc which is on the 6-12 side is getting attracted to the right side. Now the parts closer to the cut will not contribute much to that since their gravity is pulling them 'down' toward the center, and the parts at the 6 side won't contribute much either, since their gravity is pulling them 'up' toward the center. The rest of it does contribute though... a LOT. That force creates an enormous stress which gets transmitted throughout the entire length of the pipe. The pipe will be over 36000 km long. It doesn't just support itself simply by dividing it evenly... the combined force is supported axially by the ENTIRE pipe. 36000km at 8gm/cm3
enigma
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Consider this. – What if the slice were at 3, 5 or 8 o’clock? – It’s the same all around.– Evenly distributed is it not?
A single length of pipe (300mm x 50mm) will only have its’ own weight compressing into it. Everyone (hypothetically) holds all those little pieces of pipe up, until they all touch right around the world. – Each little piece has its' own weight compressing into each other. – Sounds logical enough to me!

Please be gentle, Dave.

I can sympathise with Walter. - No one would give him the time of day. Even with such a fantastic claim, shouldn't they have at least tried to understand what he was (and still is I believe!) on about? Did you read the full story? - There apparently seems to be a few of his predictions that have since been substanciated.
I have become very frustrated at times too! When you have been working on and building all sorts of models for a few years, and understanding what needs to go where etc' - Then when you've finally got it all figured out....Where do you go with it? - The 'experts' of course! - How do you think they treated him with such an extraordinary claim? He never claimed to be an expert though!
Scientists don't do that because they don't have to. They've already got the recognition. They just have to be right! - But at least they get listened to!
I've also got such a fantastic claim. Who do I go to? What do you think was the reaction?
Even if he is completely wrong, does it really matter?
If I am completely wrong....Will it matter? - At the very least we will all be gaining some kind of new knowledge and understanding.
I've gone out on a very shaky limb with this claim. If I am wrong (which of course I believe I am NOT!) then it will be me who suffers the embarassement. - Or will it be you? (Did you read my explanations? Or don't need to!)
Even Einstein was just a simple postal clerk I believe!


You've gotta be nice! Dave.

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Originally posted by davidratcliff6255:
For arguments sake (hypothetically) 10m above the ground (could be ground level at the top of Mt. Everest actually) Wouldn’t matter if it were 100m or 500m as there’s very little difference in the gravity at those variances anyway.

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Very little difference for a small object, yes. Very little difference for something the size which you are talking about, no.

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Would be suitably anchored to the ground by cables all around the circumference, so shouldn’t matter if it were off centre to gravity.

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And how can you be sure? Have you done calculations?

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Very light compared to what you would expect! - The steel tubing would only have to be around 2m in diameter, with walls about 20mm thick. There would be three, possibly four, tubes side by side to give better lateral stability. (Same as for towers)

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Do a quick calculation for that, would you? 36000km at 8gm/cm³

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Consider this. – What if the slice were at 3, 5 or 8 o’clock? – It’s the same all around.– Evenly distributed is it not?
A single length of pipe (300mm x 50mm) will only have its’ own weight compressing into it. Everyone (hypothetically) holds all those little pieces of pipe up, until they all touch right around the world. – Each little piece has its' own weight compressing into each other. – Sounds logical enough to me!

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But it doesn't work that way. Stresses get transmitted throughout the entire length of a pipe.

Let me try to illustrate a different way.

The way to determine how much stress is in a pipe, girder, etc. is to determine how much force is acting on it and divide by the area that the force is acting on. The force doesn't 'go away' if there is another piece in between the place where the force is acting and the place you're observing... it gets transmitted through.

Let's draw a free body diagram using the same 'clock' analogy (looking down from the north pole) I used before. You have a pipe running all the way around the earth. Let us make an imaginary cut to observe what forces are acting. We will make this 'cut' from 12 noon, straight down through 6. We now have two 'hemispheres'. Let's look at the two cut marks on the left side: What is the force which is pushing against those two spots from the right side? The answer is the entire mass times gravity times the sine of the angle it makes with the cut. The force doesn't go away or get distributed. The stress (force per unit area) carries through the entire structure.

I assure you it is so. If it wasn't, then there would be no reason to build supports for any size suspension bridge... the force would just get 'evenly distributed', which it doesn't. It gets transmitted to the supports.

Do you know calculus? I can explain this with numbers a little better than I can explain it with words.

enigma

If gravity pushes, then why don't we need to be tied down to the earth at all times?

enigma

Very little difference for a small object, yes. Very little difference for something the size which you are talking about, no.
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Small....Large....(feather or a brick) - So long as it is uniform all round. Traffic (more on one side than the other) might be something more relevant to consider.

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And how can you be sure? Have you done calculations?
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If the ring were off centre, then more anchorage would be needed on the higher side I would imagine.
Some years ago when discussing with another engineer, height for a tower before it would crush from self weight. The difference over 0 to 25 km was very little, so we didn't allow for in the calculations. Here we're only talking about 1 km at the most.

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Do a quick calculation for that, would you? 36000km at 8gm/cm3
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What is the answer anyway, just out of curiosity? I'm sure that it wouldn't be anything like you would normally assume with present methods!
Before I came up with this 'understanding' I imagined that the tubing would have to be something like at least 5 metres in diameter. Probably even a lot more! (Yes, there would be other problems then also)

I only came up with the obvious next step if we want to build higher or longer....I’m not an engineer (obviously). Now all that is needed is an expert to round off the edges. The 'formula' if you like!
Someone who can put aside present myths that “Design has reached its’ peak....The only way we will be able to go further is for a lighter/stronger more composite material be developed” type of messages. Someone who can think outside of the square! – Open minded, switched on type of person. - Someone who can accept that you don’t necessarily have to have years and years of training etc’. Someone that might be able to stop and wonder if somehow they might have gotten off track and followed mainstream beliefs too far.

If you want to cut pieces out everywhere. Keep cutting them out all around the ring and all you get is a smaller ring! How can you cut it in one or two places as an example when the weight is evenly distributed? What if there were a thousand cuts? I think you might be referring to present day problems (I cover this in my explanations - message section: http://groups.msn.com/DavesBridgesandTowers) Take the arch for example: Single layer of webbing versus a double layer (open web “K” type bracing) Single layer is fine for smaller spans. – Then as you go further, you get more and more sag and vertical sway. Until eventually the truss won’t even support its own weight and will of course collapse (Which is why design has reached its’ peak and also why arched bridges have basically been abandoned for bigger spans).
With a double layer of webbing, the extended struts act as a lever, which will eliminate the sag. There will still be vertical sway, so you also need to add a secondary layer of diagonal bracing. – (Same as in the tower). You need two sets of webbing instead of one. Could even turn out to be three layers yet - Main thing is that you can provide FULL restraint to stop it from buckling.

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I assure you it is so. If it wasn't, then there would be no reason to build supports for any size suspension bridge... the force would just get 'evenly distributed', which it doesn't. It gets transmitted to the supports.
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How can you compare to a suspension bridge?? With an endless bridge there are no support pylons. There is no sag and there is no sway. I fail to see how this can be used as an example for evenly distributed loads. - It's almost the complete opposite?

We are so used to instability, massive weight burying into the ground and distance, it's all too easy to dismiss an endless bridge. Does the length of pipe example make sense to any other readers here? (Everyone (hypothetically) holds all those little pieces of pipe up, until they all touch right around the world). – Each little piece has its' own weight compressing into each other. The weight of each piece of pipe is all that is compressing into itself.

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If gravity pushes, then why don't we need to be tied down to the earth at all times?

enigma
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'Gravity isn't a pulling force,' Wright says. 'If bodies in space were attracted to one another, they'd always be colliding. But that doesn't happen.' (Walter calls this the bunch-of-grapes theory since if Gravity truly attracted, then all masses would clump together into one giant cluster of grapes.)

Wright's basic idea -- which he says is borne out by his experiments and calculations -- is that gravity doesn't emanate from the earth's core, it comes from the sun.

He argues that the sun, because it is a huge mass in a constant state of combustion, emits forces which push or 'squeeze' objects toward the earth -- like Newton's apple.
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Additional clarification on 03/03/98 from Jerry W. Decker of KeelyNet

Push Gravity as I understand it is not a pushing force FROM MATTER.

Instead it is based on Aether/ZPE being omnipresent in the universe yet having varying densities in space and near matter.

In my view, matter is essentially a hole in the energy density of space. Aether/ZPE functions as a highly pressurized fluid that flows INTO these holes.

When aether/zpe flows in this fashion, we call it 'gravity'. The volume of aether/zpe which flows into mass, produces what we call 'weight'.

In its flow, aether/zpe precipitates into and PUSHES mass together, not only to sustain the physical form, but also to hold us onto the surface of the earth, much like insects being pressed against a screen (the earth surface) by a high wind.

Ok, sorry for ranting, but you get the point.

quote:

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Originally posted by davidratcliff6255:
Some years ago when discussing with another engineer, height for a tower before it would crush from self weight. The difference over 0 to 25 km was very little, so we didn't allow for in the calculations. Here we're only talking about 1 km at the most.

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Yes, but you have a huge amount of mass you're dealing with. Really big mass * really small variance is not something you can just shrug off as insignificant without actually doing calculations. My educated hunch (drawing from gravitational corrections I have done for aircraft weight calculations-->MUCH smaller mass than an orbital bridge) is that it will have some effect. It _is_ safe to do this for a building. Any error in the gravitational force would be washed out by the fact that the building is sitting on the ground, and the ground can absorb any over or undershoot weight. The bridge MUST have all forces sum to zero; EXACTLY zero. If you've got the thing tied to the ground you need to know exactly how much tension is located in the supports because if just one breaks, you've got a disaster of global proportions.

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Do a quick calculation for that, would you? 36000km at 8gm/cm3

What is the answer anyway, just out of curiosity? I'm sure that it wouldn't be anything like you would normally assume with present methods!

Before I came up with this 'understanding' I imagined that the tubing would have to be something like at least 5 metres in diameter. Probably even a lot more! (Yes, there would be other problems then also)

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Area of a slice assuming 5 meter diameter and 5cm walls.
* (250cm² - 245cm²)

= 7775 cm²

approximate length of pipe based on earth's mean equatorial radius of 6380km.

6.38 * 10 ⁸ cm

Total volume of pipe

4.96 * 10¹² cm³

density of steel ~ 8g/cm³

mass of 1 pipe ~ 3.96*10¹⁰kg

...

That's about 88 billion pounds for the layman

Just FYI, using those numbers, an error in the acceleration of gravity in the 4th decimal place (more precision than I have EVER used) still gives an error just under +-10 million pounds.

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Someone who can put aside present myths that “Design has reached its’ peak....The only way we will be able to go further is for a lighter/stronger more composite material be developed” type of messages.

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But the problem is that building materials DO have limits...

It doesn't matter how you arrange the shape, you just don't use aluminum for landing gear. It doesn't matter how much you brace it, you don't use wood for a skyscraper. It doesn't matter how much you hollow it out, you don't use steel for a missile casing.

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Someone who can think outside of the square! – Open minded, switched on type of person. - Someone who can accept that you don’t necessarily have to have years and years of training etc’. Someone that might be able to stop and wonder if somehow they might have gotten off track and followed mainstream beliefs too far.

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You don't build bridges with lunatic fringe beliefs. If you do, you get sued.

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If you want to cut pieces out everywhere. Keep cutting them out all around the ring and all you get is a smaller ring! How can you cut it in one or two places as an example when the weight is evenly distributed?

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You don't actually make the cuts. It is a mechanics of materials thought process which allows you to determine what is actually goin on structurally inside the piece of metal. If you look at just the right half of this bridge, its forces must still add up to zero! If the forces on any portion of the bridge do not add up to zero, that means that that portion of the bridge is accelerating! If you make an imaginary cut and look at the right half of the structure, you have an enormous gravitational force pulling it to the left. That force is zero'd out by two HUGE forces pushing it back to the right at the location of the imaginary cuts. It doesn't matter where those imaginary cuts are. The pipe is supporting that HUGE force at each and every imaginary cut line. That force divided by the area of the pipe is the compression stress. Every single building material has a maximum stress. If you go over that stress, the material fails. End of story.

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How can you compare to a suspension bridge??

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Because they are both bridges!!! A suspension bridge needs supports to hold it up placed at regular intervals depending on the materials used in construction. How is it that the need for supports disappears when the ends of the bridge touch itself instead of the shoreline? Do you see what I'm trying to relate to you?

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With an endless bridge there are no support pylons. There is no sag and there is no sway. I fail to see how this can be used as an example for evenly distributed loads. - It's almost the complete opposite?

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Do me a favor. Build a circular ring. Doesn't matter what it's made of. Doesn't matter how big. Popsicle sticks, used paper towel rolls, steel, whatever. Tie strings to it from many points on the ring and fed the strings down through a loop in the center. Then pull on the strings all at once. That is what gravity is doing. What you are, in effect, saying is that the structure would never collapse because: "The force is distributed throughout". You and I both know this is not the case. So why is the rule different for a scaled up version? If anything, it's even more pronounced because you still have that upper structural stress boundary to deal with.

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'Gravity isn't a pulling force,' Wright says. 'If bodies in space were attracted to one another, they'd always be colliding. But that doesn't happen.' (Walter calls this the bunch-of-grapes theory since if Gravity truly attracted, then all masses would clump together into one giant cluster of grapes.)

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Why did I ignore most of what the web page says? Because it says nothing.

F = - (G*M*m)/r³ r

That is an equation.

That is the equation for gravity.

I can do something with that.

I can use it to find out how much gravity is acting on a bridge.

I can (and have... I'll send you the MATLAB file if you want to see it) use it as a differential equation to determine the path of a planet around the sun or satellite around the earth.

This:

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Wright's basic idea -- which he says is borne out by his experiments and calculations -- is that gravity doesn't emanate from the earth's core, it comes from the sun.

He argues that the sun, because it is a huge mass in a constant state of combustion, emits forces which push or 'squeeze' objects toward the earth -- like Newton's apple.
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Additional clarification on 03/03/98 from Jerry W. Decker of KeelyNet

Push Gravity as I understand it is not a pushing force FROM MATTER.

Instead it is based on Aether/ZPE being omnipresent in the universe yet having varying densities in space and near matter.

In my view, matter is essentially a hole in the energy density of space. Aether/ZPE functions as a highly pressurized fluid that flows INTO these holes.

When aether/zpe flows in this fashion, we call it 'gravity'. The volume of aether/zpe which flows into mass, produces what we call 'weight'.

In its flow, aether/zpe precipitates into and PUSHES mass together, not only to sustain the physical form, but also to hold us onto the surface of the earth, much like insects being pressed against a screen (the earth surface) by a high wind.

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Is gibberish.

I cannot do anything with it.

I cannot make any predictions with it.

I cannot make any calculations with it.

I cannot plug it into a computer program to see if it generates orbits of the planets.

I cannot validate it in any way, shape, or form.

How does this "push" force vary with distance? Does the "push" force vary such that our gravitational acceleration doesn't change regardless of our distance from the sun?

If all mass pushes all other mass away, how the heck did the planets form in the first place?!? How is it possible that objects get attracted toward each other ALL THE TIME?!? Why is it that all over the universe there are globs of gas coalescing together to form stars?!? Why do galaxies constantly get drawn towards each other all over the known universe?

No, really... I'm actually curious how his "model" of the universe actually works. If I don't have any formulas to look at though, It's kinda useless to me. In a matter of a few years, I will probably be designing satellites and spacecraft for a living. If Netwon, Kepler, Copernicus, et al. were wrong, (despite the fact that every single test of their formulas says that they're right), I think I had better find out about it now. Unfortulately, though, all I saw on that web page was yet another crackpot rambling on about how science is fundamentally misguided without giving the mathematical proof to back it up.

Don't get me wrong, David.

I am a dreamer too.

I am a big time space geek.

I would love nothing more than to have orbital bridges, interstellar spacecraft, lunar and Mars bases, space elevators, and any other of countless ideas to be possible and feasable in the near future.

The difference is that I have made the commitment to myself to find out how the universe really works so I can effectively work within the bounds of reality and actually get things out of the realms of science fiction and into the realms of science.

I have absolutely no reason to lie to you about why this bridge idea of yours cannot work in it's present state. I have studied physics, statics, dynamics, mechanics of materials, aerospace structures, dynamics of aerospace systems, orbital dynamics, and many, many other topics, And I assure you:

The bridge cannot and will not be able to sustain it's own weight

enigma

Thank you FZ. The original question was: Is endless spanning (orbital) bridge possible? Without Walter Wrights' concept. The main part of this website that took my interest was about the test carried out in Culumet with the piano wire, which seemed separate from Walters’ proposal and therefore also more believable. Does anyone have any information on the piano wire subject? Perhaps this test should be redone, as it appears undecided. It would also disprove Walters theory I should think!
I did not fully understand the rest of the story myself, but felt that it should be mentioned anyway. The last thing I wanted was to have a debate on the subject, and I agree that it should not have introduced with zero evidence. – My apologies!
Overall, I don’t think that claims as such are harmful to anyone, but rather reminds us to keep an open mind. After all, at one time the world was assumed flat!

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I'm getting a little irritated, here. I feel like I'm talking to a wall
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How do you think I feel? I’ve been pounding my head on a wall for almost a decade now!
For the life of me I cannot see how you can totally ignore my understanding of the bridge and be so insistent that your equation (which seems to vary from others anyway) is the be all to end all! No doubt you will have an answer for this one too!
The whole crust of our planet is made up of a mixture of materials weaker than steel, and although they are not hovering above ground level, there are no real lateral forces besides gravity itself. The centre of the Earth is not solid, yet there is a lot more pressure from gravity, so why doesn't it collapse within?
Probably because it's all solid rock and acts like a stone arch? I doubt it! Internal pressure? Maybe! – Or have we just got it all wrong!

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. If you've got the thing tied to the ground you need to know exactly how much tension is located in the supports because if just one breaks, you've got a disaster of global proportions.
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If just one breaks? – Surely there would be at least double the anchors required.

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Area of a slice assuming 5 meter diameter and 5cm walls
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Why did you assume a 5 metre diameter with 50mm walls instead of the 2 metre x 20mm that I am proposing? And why also did you give the answer in pounds instead of tons? Possibly so that it would be in billions instead of millions? – Sounds a bit better for your argument doesn’t it?

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Do me a favor. Build a circular ring. Doesn't matter what it's made of. Doesn't matter how big. Popsicle sticks, used paper towel rolls, steel, whatever. Tie strings to it from many points on the ring and fed the strings down through a loop in the center. Then pull on the strings all at once. That is what gravity is doing. What you are, in effect, saying is that the structure would never collapse because: "The force is distributed throughout". You and I both know this is not the case. So why is the rule different for a scaled up version?
If anything, it's even more pronounced because you still have that upper structural stress boundary to deal with.
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I love this example, it’s even better than my “Hold up a length of pipe” idea! – So you attach these strings to the loop in the centre and pull them. How hard do you pull them? The same weight as the ring? After all that is basically the same as what I have been suggesting all along. You would get buckling in the lateral plane before it would even look like collapsing! Even at ten or twenty times the weight! But no, it doesn’t work that way!
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Enigma, you came at me with both guns blaring right from the start. Singling out things like 10 metres from the ground – Impossible (theoretical remember)….”light”. No, sorry. Steel is enormously heavy. And to a degree, used Walter Wrights’ theory to try and discredit me. I realise that I’ve got a bit of an attitude myself (just wait till you find my poem), but really, you shouldn’t try to be so pessimistic. It’s almost unbearable.

I’ve been thinking of starting up another thread on a “whip” tower (I guess you would call it). – Used for….No I won’t go into it here. I hope that you will contribute though, as even criticism can have its rewards. But please try to remember that it is only a theory. I do believe that it will be possible but there could be something overlooked.

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To anyone (visitors) reading this thread, please vote on the poll of “endless bridge” topic. - Yes, No or not sure. (located in (sorry) “How Stuff Works” forum)

Dave.

(Go easy on Walter will you please, as he’d now be somewhere around ninety years old and obviously is not a rocket scientist.- He didn’t ask to be in this conversation and I’m sure that he fully believes in what he proposes).

And about the earth. The reason why it does not collapse is that it has nowhere to collapse into. But if it does, in terms of volcanos, it is pretty clear there are big pressures. And that is the reason why the centre of the earth is solid. Steel is mallable, can be bent and molded. Under this sort of compression, any frame will distort.

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Originally posted by davidratcliff6255:
The original question was: Is endless spanning (orbital) bridge possible?

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To which I gave you my answer. You didn't like it, so why did you even bother to ask it in the first place?

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<snip>
Does anyone have any information on the piano wire subject?

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I don't. Do you (or he) have the results posted anywhere, or should we merely take his word that it is so?

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For the life of me I cannot see how you can totally ignore my understanding of the bridge and be so insistent that your equation

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Because I see the mistake you are making! You are neglecting internal stresses and shears which arise in each and every object anytime they are subjected to external loadings. Why is it that an infinite tower can't sustain its own weight? According to a force diagram, there is certainly no net force, and thus no acceleration. Why can't it support an infinite weight?

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(which seems to vary from others anyway) is the be all to end all! No doubt you will have an answer for this one too!

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Go ask your engineer friend then what the maximum internal stress of steel is then, if you don't believe me. For pete's sake, you can look it up yourself if you want!

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The whole crust of our planet is made up of a mixture of materials weaker than steel, and although they are not hovering above ground level, there are no real lateral forces besides gravity itself. The centre of the Earth is not solid, yet there is a lot more pressure from gravity, so why doesn't it collapse within?

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Bouyancy. The interior is denser than the crust. Do you need me to post the derivation of Archimedes principle and dig into the library geology journals to find the estimated densities of core material and mantle compared to crust?

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Why did you assume a 5 metre diameter with 50mm walls instead of the 2 metre x 20mm that I am proposing?

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Because you said it would be 5 meter diameter in the thread immediately preceding it:

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Before I came up with this 'understanding' I imagined that the tubing would have to be something like at least 5 metres in diameter. Probably even a lot more!

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I used 1/10th the diameter as the wall thickness because that is the ratio which you can assume a thin walled structure as an approximation.

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And why also did you give the answer in pounds instead of tons? Possibly so that it would be in billions instead of millions? – Sounds a bit better for your argument doesn’t it?

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Now I'm being dishonest, is it? Pounds/tons... 6 of one half dozen of the other. I originally put it in Newtons which is the metric 'pound', but went back and edited it because most people don't have a feel for how much a Newton is. Now I'm being dishonest or manipulating numbers because I didn't convert it again to tons. It still weighs the same last I checked. As long as we're talking about my 'manipulation' of numbers to suit my needs, it does appear that I am the only person here who has done any calculations at all! Did I make any errors? Did I lie anywhere?

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I love this example, it’s even better than my “Hold up a length of pipe” idea! – So you attach these strings to the loop in the centre and pull them. How hard do you pull them? The same weight as the ring? After all that is basically the same as what I have been suggesting all along. You would get buckling in the lateral plane before it would even look like collapsing! Even at ten or twenty times the weight! But no, it doesn’t work that way!

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Sigh. So much for trying to explain something. I should have expected that you'd write it off without thinking about it.

Fine Dave. Assume that the device is braced against motion in the lateral direction. Does that make you happier? Seriously. Think about it. If what you are saying is correct, then you could put as much tension as you want and it wouldn't collapse in on itself.

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Enigma, you came at me with both guns blaring right from the start.

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Actually, that was not my intention, nor was it my action. You asked: "Can this work, yes or no." I said: "No, it can't, here is why:"

Since when is that attacking you? You did ask the question, didn't you? Why bother asking if you only will accept things that agree with what you want to hear?

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Singling out things like 10 metres from the ground – Impossible (theoretical remember)….”light”. No, sorry. Steel is enormously heavy.

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So I shouldn't have cited examples of problems I saw? I should have just said: "No, it won't work" and left it at that?

Your 10 meter statement seemed to me like you were neglecting altitude differences on the surface. You corrected me and said that it could follow the surface. I pointed out that doing so makes it even more unstable. You summarily ignored my point as irrelevant and wrong.

I even did the calculations to prove that it isn't light. You did ask me to do that, didn't you? Now I'm being bellicose because I did that for you?

Why bother asking at all?

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And to a degree, used Walter Wrights’ theory to try and discredit me.

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You are referencing him as a qualified source. As a scientist, I looked at what he said and saw absolutely nothing which resembled a viable, testable prediction or formula.

I didn't just say: "That's bunk!", I said: "That's bunk... here's why!"

If you didn't want to discuss it, why did you even bring it up?

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I realise that I’ve got a bit of an attitude myself (just wait till you find my poem), but really, you shouldn’t try to be so pessimistic. It’s almost unbearable.

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I see how the idea will fail, and voice it. That pessimism, now? Did I ever say: "This will never work!"? No. I said:

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this bridge idea of yours cannot work in it's present state.

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I’ve been thinking of starting up another thread on a “whip” tower (I guess you would call it). – Used for….No I won’t go into it here. I hope that you will contribute though, as even criticism can have its rewards. But please try to remember that it is only a theory. I do believe that it will be possible but there could be something overlooked.

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But if people who point out things that you overlook get their posts ignored, what is the point of even asking it?

You asked: "Can this bridge work?" I pointed out: "You overlooked compressive stress." You write it off without even considering even the potential that I know what I'm talking about. Have you ever studied mechanics of materials? Do you know how to obtain the interior stresses of beams or pipes? Have I not learned something that you have? If so, let me know... I'll be happy to look over your facts to determine what's actually going on. I love these far out ideas! Really! I've got a few of my own. Do a search for 'space elevator' on these forums.

If you are going to continue summarily ignoring my points as irrelevant, however, why should I, or anyone else, bother? It seems like you've already got the answer, and you're not leaving till you get it.

If you want, I could try again to explain why the internal stresses will cause the bridge to fail. I could spend some time and draw up visuals explaining the method to determine internal stresses and show why the thought process which you are writing of as absurd is actually valid and used each and every day by structural engineers all over the planet.

If you're going to continue to write off any criticism, I'm not going to waste my time, though. To be honest, if you're going to continue with those methods, I don't see why you should even waste your own time asking.

enigma

On my website there is a page of drawings of models that I have built using pvc conduit and 1 mm piano wire, which is mentioned in the explanations (open web section in messages). So, yes I am very familiar with it after receiving numerous needle pricks in the fingertips. The wire is also very stiff and curved.
Plumb bobs were used in the experiment:

From the page:
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At Calumet, Michigan, in 1901 they took two piano wires 4,250 feet long plumb bobs attached and dropped them down two mine shafts 4,250 feet apart. They expected the pull of gravity, which is supposed to be in the center of the earth, to pull these two plumb bobs closer together. Much to their surprise they found out the wires at the bottom WERE FURTHER APART than they were at the top. This led them to believe that: 'Maybe there is no such thing as MASS ATTRACTION.'
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This is the section that stood out to me. It is the ONLY section that really took my interest! It appears to be separate from Walter Wrights’ section, and I don’t think that he had even once referred to it. - But I did wonder if there could have been other magnetic forces acting around the wires that caused them to repel each other. – Either way I think that the experiment should be done again so that an explanation can be given and the subject FINALISED!! - And I still submit that ANY claim, no matter how bazaar it may sound, should be investigated.
Before I came across this report. A couple of days prior, I had even CONCEDED on the endless bridge theory, due to explanations given during discussion by a well versed engineer.

The discussion:
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If you had a self supporting steel ring around the equator, and provided it with full restraint against buckling, the stress in the steel would be around 56,000ksi (the math is simple: stress=pressure*radius/thickness).
This is about 500 times greater strength than is presently available on the market. Yes, membrane structures such as pipes and soap bubbles are very efficient, but not that efficient. Why did you think that this would be possible?

(REPLY)
The formula of stress Mr Michael has written, to my knowledge, is that of hoop stress which gets induced due to internal pressure of a cylindrical container ( in cross section, it will also look similar to a tube in question). In the situation under discussion, the only stress that will get induced- is external, centripetal, uniformly distributed, all unidirectional and due to earth's gravitational force (self weight) only! How the two can be identical? Can you derive the formula mathematically?

(REPLY)
Yes, stress=pr/t is the hoop stress formula. The reason i used this formula is that a ring all the way around the earth is a hoop with a uniform stress along its radius.

Consider a unit width of pipe. - Applied inward gravitational pressure is proportional to thickness: p =gravity*density*thickness- Therefore stress = d*g*t*r/t = d*g*r
In SI units, a hoop all the way around the world is: r=5000,000m g=9.8m/s2 d=7850kg/m3 (steel)
stress=385GPa

(Separate reply to my question)________________________________________________________________
2. the reason the earth does not implode on itself, and the reason that a ring around the earth will, is mostly due to one basic thing. consider a solid ball of rubber and a tennis ball. which is stronger?
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It was this ‘piano wire’ experiment that started me thinking again, but I needed some way of validating my claim WITHOUT the piano wire statement. – That was when I came to the thought about holding up a length of tubing.
Soon afterwards I posted a poll on the endless bridge as well as the uniform tower to 3.5 km – Yes, No or Not sure. – Mr. Michael voted “Yes” to both questions!)
Surely it must have you (and others) at least wondering about it! – With that one piece of tube, how much compression is there? – The weight of the tubing only! To me it sounds logical enough that, when the tube joins end to end, the total compression will be the total weight of the tubing - plus stabilising method. – Evenly distributed all around the ring! It is an example that is as plain as day!

This claim of an endless bridge, I KNOW is very hard to fathom! Since coming up with my initial discovery, a double layer of webbing instead of single (believe me there were obstacles there that questioned my way of thinking too!), the first thing you have to wonder is “just how far can this thing actually go!!”
That is when you start to REALLY wonder. I’m still not saying that I am absolutely right or without a doubt, but so far, there has been nothing that has been able to convince me otherwise. And believe me if there were, I will be the first to admit that I was wrong. I have busted by brain trying to imagine other examples (and thought processes) with no luck. – And I’m STILL trying! There needs to be a lot better example than the ones given!
Again, I suggest that we are convinced that an endless bridge would not be possible because we are so used to such massive weight pushing into the ground, and distance. It is simply too inconceivable. Any ‘trained’ person will have even more difficulty accepting this theory because they have SEEN these massive weights and they have also accepted (from the book) that it is impossible! – It would be like someone trying to convince me that bricks should be laid upright instead of flat!
I am not trying to discredit anyone who truly believes in his or her understanding as you obviously do, but if I now suggest that you hold up a piece of pipe (or any object for that matter) and think about it, well. - Have a go!! – ‘feel’ how heavy it is. Picture everyone holding up a piece of their own- each with its own weight. Until it all joins up in a circle. And then try to explain why there are these “extra” forces (remembering that it will not buckle because it is fully restrained)!
How about we just “agree to disagree” for now? – Unless you have a better example.

(Anyone reading this message please post your thoughts on the poll (how stuff works segment), so that we can ALL have a better understanding of overall thoughts on the subject. It will never be conclusive, and we could go on arguing forever, but at least we will get a clearer understanding of what the general view is since I have added my thoughts) Thanx.

You sure you’re not referring to ground supported structures when you talk about internal stresses and shears?
This is EXACTLY what I talked about earlier. Total ignorance! – You don’t even have to entertain my thoughts because YOU KNOW….YOU ARE THE EXPERT! You’ve spent many years in the game. Then some “untrained” little “twerp” comes along and this is your big chance to demonstrate your sophisticated knowledge and put this person in their place. Look at me….I’m an engineer! – I’m good. Then you turn around and say you’re a big time space geek! In a couple of years I’ll be designing satellites! You will refuse to back down! If you have made a commitment to yourself to find out how the universe REALLY works then you must also be ASSUMING that you are IMMORTAL. And YOU talk about “lunatic fringe beliefs”!!

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Why did you assume a 5 metre diameter with 50mm walls instead of the 2 metre x 20mm that I am proposing?
(REPLY)
Because you said it would be 5 meter diameter in the thread immediately preceding it:

quote:
Before I came up with this 'understanding' I imagined that the tubing would have to be something like at least 5 metres in diameter. Probably even a lot more!
(REPLY)
I used 1/10th the diameter as the wall thickness because that is the ratio which you can assume a thin walled structure as an approximation.

quote:
And why also did you give the answer in pounds instead of tons? Possibly so that it would be in billions instead of millions? – Sounds a bit better for your argument doesn’t it?
(REPLY)
Now I'm being dishonest, is it? Pounds/tons... 6 of one half dozen of the other. I originally put it in Newtons which is the metric 'pound', but went back and edited it because most people don't have a feel for how much a Newton is. Now I'm being dishonest or manipulating numbers because I didn't convert it again to tons. It still weighs the same last I checked. As long as we're talking about my 'manipulation' of numbers to suit my needs, it does appear that I am the only person here who has done any calculations at all! Did I make any errors? Did I lie anywhere?
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Whatever happened to your original calculation….36000km at 8gm/cm3 (did you not understand at the time that I was suggesting a tube 2m x 20mm?) 5 metres was clearly my assumption BEFORE! – Where did I say that it WOULD be 5 meter diameter?? Selective editing at its best! – Put all of my quotes together and what have you got? – Cheap shots! – And I did not once use the word dishonest!
If anything, it makes it look like you are just trying to score points. Avoiding the REAL issues! Perhaps my explanations might even be starting to make sense to you? – But you’ve come this far….can’t back down now!

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Sigh. So much for trying to explain something. I should have expected that you'd write it off without thinking about it.
Fine Dave. Assume that the device is braced against motion in the lateral direction. Does that make you happier? Seriously. Think about it. If what you are saying is correct, then you could put as much tension as you want and it wouldn't collapse in on itself.
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And still thinking!! – And I won’t be satisfied until I understand what you are trying to tell me! – Did you try my way though? Somehow I doubt it very much!
If what I am saying is correct??? Where did I ever suggest that that you could put as much tension in it as you want? I did however suggest 10 to 20 times before it would collapse – probably even a lot more! And I stand by that statement! – Do you also aspire to be a politician some day? - Now I don’t mind a good debate, and I can put up with a little *****ing and snickering along the way, but this goes beyond! Why do you have to misconstrue every little thing I try to say? Will it ever end??? You’ve got a MAJOR attitude problem!

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If you are willing, Dave, you still haven't gotten me to the point of throwing up my hands in disgust yet.
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That’s good! Even excellent! If you can put aside our differences and concentrate on the real issue. Please TRY to keep the sarcasm out of it though. And PLEASE don’t try to construe my words! By the sound of it I don’t think you even realise you have this attitude, but I’m certain you are very “into” these topics and give you full credit for that. I’ll even let you have the LAST SAY in reply to my comments! It’s almost like this is all a big game to you!
YES, please try to explain why these internal stresses will cause the bridge to fail. I assure you that I AM LISTENING. Also, any information you can pass on. – I might not understand any equations or formulas, but will seek help with them if need be.
I did the search on space elevator. Are they seriously thinking about it? Sounds a bit risky to me! Have a look at my proposal for a “Whip Tower” and see what you think. – I realise that it too sounds a bit crazy, but it should at least be studied. I am certain that the tower itself is workable, and that there will be no damage by curving of the tubing. I think that this subject would really interest you too as you seem to be very “into” formulas and such, so give it a go!
For the moment I would like to propose a “truce” and suggest that we “agree to disagree” on the subject at this stage.
Dave.

(Anyone reading this message please post your thoughts on the poll (how stuff works segment), so that we can ALL have a better understanding of overall thoughts on the subject. It will never be conclusive, and we could go on arguing forever, but at least we will get a clearer understanding of what the general view is since I have added my thoughts)
Thanx.