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Flat Earth Discussion Boards => Flat Earth Theory => Topic started by: pricelesspearl on September 12, 2019, 03:42:47 PM

Title: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 12, 2019, 03:42:47 PM
So I have been making my way through Earth Not A Globe and came across this on page 110

“…If a delicate spirit-level be firmly placed upon a rock or upon the most solid foundation which it is possible to construct, the very curious phenomenon will be observed of constant change in the position of the air-bubble.  However carefully the “level” may be adjusted, and the instrument protected from the atmosphere, the “bubble” will not maintain its position may seconds together…”
 

And it made me wonder how a spirit level could even work on a flat earth when they are designed to indicate “level” as “perpendicular to gravity”.  “Level” is a relative term, so when the bubble is in the middle, what is the spirit level using as a baseline for “level”, if not gravity? And what is the mechanism for determining something is level relative to the baseline?

Anybody have any ideas?
Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 13, 2019, 10:49:52 AM
what is the spirit level using as a baseline for “level”, if not gravity?
UA, broadly speaking.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 13, 2019, 03:52:21 PM
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UA, broadly speaking.

That was my initial thought, but if the low end and the high end are accelerating at the same rate, the bubble won't move whether it is at an angle or not. The only way to get the bubble to move from a tilt to level is if more force is applied to one end.

Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 13, 2019, 04:21:41 PM
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UA, broadly speaking.

That was my initial thought, but if the low end and the high end are accelerating at the same rate, the bubble won't move whether it is at an angle or not. The only way to get the bubble to move from a tilt to level is if more force is applied to one end.

But the force of gravity on either end is the same on both ends too, so what's the difference?
I think this would work fine with UA.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 13, 2019, 04:50:11 PM
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But the force of gravity on either end is the same on both ends too, so what's the difference?
I think this would work fine with UA.

The force of gravity is the same on both ends only if it is level.  The reason the bubble migrates to the low end is because the force of gravity is stronger on the low end.  That is how a spirit level works...the bubble in the middle indicates that the gravitational force is equal across the length of the spirit level. 

With gravity, when the bubble is not in the middle, it indicates an unequal gravitational force across the length of the spirit level. With UA, then, when the bubble is not in the middle, that would mean an unequal force created by acceleration across the length. But if both ends are accelerating at the same rate, how can that be?



Title: Re: Spirit Levels on a Flat Earth
Post by: obiba on September 13, 2019, 04:54:48 PM
So I have been making my way through Earth Not A Globe and came across this on page 110

“…If a delicate spirit-level be firmly placed upon a rock or upon the most solid foundation which it is possible to construct, the very curious phenomenon will be observed of constant change in the position of the air-bubble.  However carefully the “level” may be adjusted, and the instrument protected from the atmosphere, the “bubble” will not maintain its position may seconds together…”
 

And it made me wonder how a spirit level could even work on a flat earth when they are designed to indicate “level” as “perpendicular to gravity”.  “Level” is a relative term, so when the bubble is in the middle, what is the spirit level using as a baseline for “level”, if not gravity? And what is the mechanism for determining something is level relative to the baseline?

Anybody have any ideas?
not gravity but density

Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 13, 2019, 05:07:13 PM
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not gravity but density

It can't be density and/or buoyancy because (among other reasons), those are up/down phenomena. The bubble always stays at the top of the vial no matter if the angle of the spirit level...because its a bubble and that is what bubbles do.  The bubble can only move side to side, along the axis of the vial and density or buoyancy cannot account for the bubble moving side to side.
Title: Re: Spirit Levels on a Flat Earth
Post by: obiba on September 13, 2019, 07:06:05 PM
it is not the bubble but the water that is moving...
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 13, 2019, 07:27:03 PM
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it is not the bubble but the water that is moving...

 ::)     What makes the water move?

And that still wouldn't answer the question of "level relative to what?"
Title: Re: Spirit Levels on a Flat Earth
Post by: obiba on September 14, 2019, 01:49:42 PM
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it is not the bubble but the water that is moving...

 ::)     What makes the water move?

And that still wouldn't answer the question of "level relative to what?"

don t you understand that water density is defferent  from the air density it is why the drops of water fall from the sky when it is raining
Title: Re: Spirit Levels on a Flat Earth
Post by: obiba on September 14, 2019, 01:52:48 PM
and how do you explain that if you take out the azote from atmosphere the supposed gravity stop working?
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 14, 2019, 03:28:44 PM


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don t you understand that water density is defferent  from the air density it is why the drops of water fall from the sky when it is raining

And don’t you understand that the only air in the vial of a spirit level is the bubble, but yet the water never “falls” through it.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 14, 2019, 03:30:00 PM
and how do you explain that if you take out the azote from atmosphere the supposed gravity stop working?

Funny that gravity still works in a vacuum though
Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 14, 2019, 07:19:18 PM
The reason the bubble migrates to the low end is because the force of gravity is stronger on the low end.  That is how a spirit level works...the bubble in the middle indicates that the gravitational force is equal across the length of the spirit level. 
This is not at all how a spirit level works in RET (or in any model, really). The air bubble moves towards the top because the density of air is lower than the density of the alcohol. The reason the bubble moves to the centre as the spirit level becomes level is simple - the inside of the tube is slightly curved.

The differences in gravity on both sides of the level would be miniscule, and absolutely insignificant compared to, say, the surface tension of the liquid.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 14, 2019, 08:13:25 PM
The reason the bubble migrates to the low end is because the force of gravity is stronger on the low end.  That is how a spirit level works...the bubble in the middle indicates that the gravitational force is equal across the length of the spirit level. 
This is not at all how a spirit level works in RET (or in any model, really). The air bubble moves towards the top because the density of air is lower than the density of the alcohol. The reason the bubble moves to the centre as the spirit level becomes level is simple - the inside of the tube is slightly curved.

The differences in gravity on both sides of the level would be miniscule, and absolutely insignificant compared to, say, the surface tension of the liquid.

That’s exactly how a spirit level works.  The bubble is always on the top of the vial because of density, but it’s only in the top of the middle when it’s level.

https://www.leveldevelopments.com/

I am on my phone so it’s hard to cut and paste but go to the section titled “Principles”.  I think you’ll find they specifically say the level works by gravity acting on the fluid in the vial.  Or really just go to any website or book about surveying and how to read a spirit level. The technical term that surveyors use for level is “perpendicular to gravity”.

Gravity is the baseline for level in RE model. What is the baseline in the FE model?





Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 15, 2019, 08:33:42 AM
That’s exactly how a spirit level works.
You're simply mistaken about this. The source you provided does not claim that the spirit level works due to a difference in gravity acting on two points merely an inch apart. This would be miniscule.

To drive the point home, you can use something like https://www.vcalc.com/wiki/KurtHeckman/Gravity+Acceleration+by+Altitude to compare the value of g on the round Earth's surface to the value of g 2.5cm off the ground - the most generous case for what you propose. You will notice that the difference is 0.00000008%20%5Cfrac%7Bm%7D%7Bs%5E2%7D. Knowing this, we can apply basic classical mechanics to estimate the time the bubble would take to traverse the 2.5cm tube if this, and nothing else, were the factor responsible for the bubble's movement.

x%3D%5Cfrac%7B1%7D%7B2%7Dat%5E2

0.025%3D0.5%20%5Ctimes%200.00000008%20%5Ctimes%20t%5E2

0.025%3D0.00000004%20%5Ctimes%20t%5E2

%5Cfrac%7B0.025%7D%7B0.00000004%7D%3Dt%5E2

t%5E2%20%3D%20625000

t%20%3D%20%5Csqrt%7B625000%7D%20%3D%20790.57%5Bs%5D

Since it does not take 13 minutes for the bubble to move from the bottom to top when the level is placed vertically, we can dismiss your proposal as patent nonsense.

While your interpretation of what you read leaves a lot to be desirted, it's obvious that in RET it will be due to gravity acting on the vial (or, well, the liquid and gas inside of it). The denser liquid tends downward, thus the bubble goes up. The reason "up" is in the centre of the tube when the spirit level is level is the curvature of the tube.

To summarise: in RET it's due to gravity (not a difference of gravity throughout the tube). In FET, it's due to UA, a force that's completely analogous in this scenario.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 15, 2019, 10:45:31 PM
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You're simply mistaken about this. The source you provided does not claim that the spirit level works due to a difference in gravity acting on two points merely an inch apart. This would be miniscule.

A level line is a line in a level surface. A level surface has all points perpendicular to the direction of gravity and hence is curved.

https://link.springer.com/chapter/10.1007%2F978-1-4757-1188-2_6

For, if one imagines holding a spirit level near the intruding mass, its extra gravitational pull draws the fluid of the level toward the mass thus forcing the bubble away.

https://history.nasa.gov/SP-4211/ch11-4.htm

“Level Surface …A level surface is a curved surface, every point on which is equidistant from the centre of the earth
https://books.google.com/books?

id=0fUIAAAAIAAJ&pg=PA72&lpg=PA72&dq=%22spirit+level%22+gravity+surveying&source=bl&ots=xhQKkEEHpa&sig=ACfU3U2MFyw7M0Z2wHWi6XpKaCDIZpFxHQ&hl=en&sa=X&ved=2ahUKEwiJpMKEztPkAhWP9Z4KHVD1DqkQ6AEwDXoECAsQAQ#v=onepage&q&f=false

Such a reference height is a level line or level surface and is defined as a surface on which all points are normal to the direction of gravity as defined by a suspended plumb bob. Since the surface of the Earth is curved, level surfaces are also curved, as shown in figure 2.1.
https://link.springer.com/chapter/10.1007/978-1-349-07348-1_2

93. Level Surface- A level surface is a curved surface which at every point is perpendicular to the direction of gravity
https://books.google.com/books?

https://books.google.com/books?id=G6UEAAAAMAAJ&pg=PA72&lpg=PA72&dq=all+points+equal+level+gravity+%22spirit+level%22&source=bl&ots=s6YXL10XzT&sig=ACfU3U1667EJZea_0bTNuyvlioZUPsam4w&hl=en&sa=X&ved=2ahUKEwic1frR5tPkAhU0Pn0KHaF8D_YQ6AEwDnoECAYQAQ#v=onepage&q&f=false

I'll make this as simple as possible.  When all points are perpendicular to gravity, all points are the same distance to the center of gravity and therefore all points are subject to the same gravitational pull.  When all points are not perpendicular to gravity, some points are closer to the center of gravity and are therefore subject to more gravitational pull. Since fluids will respond to any force acting upon it, and fluids are more sensitive to gravitational pull than solids, a fluid will be pulled lower when it is closer to the center of gravity due to the increased level of gravitational pull.

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Knowing this, we can apply basic classical mechanics to estimate the time the bubble would take to traverse the 2.5cm tube if this, and nothing else, were the factor responsible for the bubble's movement.

I have no idea what those calculations are supposed to prove. Gravity doesn't move the bubble at all.  Gravity determines where it falls when it is stationary and not subject to any other force.  Have you ever even used one?  An external force must be applied to move the bubble.

For, if one imagines holding a spirit level near the intruding mass, its extra gravitational pull draws the fluid of the level toward the mass thus forcing the bubble away.To counter this effect the end of the level nearer the mass must be tipped up to recenter the bubble. In other words, the level surface tips upward as one approaches the mass.

https://history.nasa.gov/SP-4211/ch11-4.htm

A fine-pitch tilting screw is turned manually to center the bubble in the vial of the spirit level. Compensator instruments depend on a: pendulous reflecting component, the compensator, within the optical system of the telescope. Responding to the attraction of gravity automatically renders the line of sight horizontal.

https://www.ngs.noaa.gov/PUBS_LIB/GeodeticLeveling_Manual_NOS_NGS_3.pdf        (page 3-11)

The bubble should sit between the graduation marks. Where the bubble sits over or out of the graduation marks, adjust the left or right side. When the left side is too high the bubble will sit on the right side of the graduation marks and vice-versa for the opposite side. Using this as a guide, you can now make the necessary adjustment to create a perfectly level project

https://www.home-dzine.co.za/diy/diy-spiritlevel.htm

The only direction the bubble can move is along the axis of the tube. Once that axis is perpendicular to gravity, gravity does no work on the liquid, so the bubble stays in a fixed location.

https://forums.anandtech.com/threads/so-how-exactly-does-a-level-work.1745763/

To use a spirit level, set the body against the surface that you want to level. Since liquids naturally seek their own level, the air bubble in the capsule will be perfectly centered between the marks on the capsule when the spirit level is level. If the bubble floats to the left, raise the right side, and vice-versa.

https://everything2.com/title/Spirit+level

 
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The reason "up" is in the centre of the tube when the spirit level is level is the curvature of the tube.

The bubble shows "up" whether it is in the middle of the tube or not.  It is always sits at the highest point of tube but only when it is level is the curve the highest point. If the level is tilted down to the right, the highest level will be slightly to the left of the curve and vice versa.

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The reason "up" is in the centre of the tube when the spirit level is level is the curvature of the tube.

So UA causes things to move side to side?  That is the only direction the bubble moves.  As I pointed out above...it is always at the top of the tube and only moves side to side along the axis of tube, but it always at the top of tube.  A spirit level with a barrel vial doesn't even have a curve.. the bubble only moves side to side along the axis of the tube.



Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 15, 2019, 11:54:36 PM
In case my explanation above was not clear enough, I’ll try another way.

If we define level as “perpendicular to gravity”… Gravity is a vertical force, so perpendicular means that level is at a right angle, perfectly horizontal to gravity.  In order to level or “unlevel” something, you can increase or decrease the level of gravitational force by changing the position of the object…by moving closer or farther away from the center of gravity.

If we define level as “perpendicular to UA”… UA is a vertical force, so perpendicular means that level is at a right angle, perfectly horizontal to UA.  In order to level or “unlevel” something, you cannot increase or decrease the level of UA by changing the position of the object.  UA is constant and consistent.  No matter what position the object is in, it will always be subject to the same level of “gravitational force” caused by UA.  Everything would have to level or "unlevel" all the time.  Moving an object makes no difference on the level of force.

So what does level mean on a flat earth with UA? And how is it measured with a spirit level? What changes relative to UA and the level cause the bubble to move?
Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 16, 2019, 05:11:53 AM
UA is constant and consistent.  No matter what position the object is in, it will always be subject to the same level of “gravitational force” caused by UA.  Everything would have to level or "unlevel" all the time.  Moving an object makes no difference on the level of force
I already explained why the difference in gravitational force cannot be the phenomenon responsible for the spirit level's function. Your objection relies on this fundamentally flawed assumption.

There is also the side issue of you completely ignoring celestial gravitation (which renders the product force both not constant and not consistent), but I think we should leave FET out of this when your understanding of the physics at play is so limited.

If we define level as “perpendicular to gravity”… Gravity is a vertical force, so perpendicular means that level is at a right angle, perfectly horizontal to gravity.  In order to level or “unlevel” something, you can increase or decrease the level of gravitational force by changing the position of the object…by moving closer or farther away from the center of gravity.
No, I already provided you with the calculations to explain why this is nonsense. If a change in magnitude of gravitational force was the main factor here, it would take the bubble something in the order of 13 minutes to traverse the tube. This does not occur in reality.

The force can be assumed to be constant for all practical intents and purposes. The change to the vector you should be focusing on is the direction, not magnitude.

I'm sorry, but we cannot meaningfully proceed with this conversation if you refuse to acknowledge how this works. None of the quotes you provided come even close to substantiating your position. All you've done is define "level" within the context of RET, and "explained" the consequences of tilting a spirit level. Meanwhile, your misunderstanding is in understanding how it happens, not that it does.

Statements like "fluids are more sensitive to gravitational pull than solids" only serve to further illustrate your inability to understand simple physics, and that's long before we even start discussing FET.

As always, I suggest an experimental approach if you want to broaden your understanding. Take a spirit level and try using it in a moving elevator, particularly as it accelerates and decelerates. Observe its impact (or lack thereof) on the bubble until you've reached your conclusions.
Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 16, 2019, 09:21:02 AM
Never thought I'd type this phrase but: Pete is right here.
The difference in gravity between two sides of a non-level spirit level are far too small to have an effect here.
Spirit levels do work because of the force of gravity but if gravity was replaced by UA that acceleration would cause an equivalent force which would mean they'd still work.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 16, 2019, 03:40:35 PM
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I'm sorry, but we cannot meaningfully proceed with this conversation if you refuse to acknowledge how this works. None of the quotes you provided come even close to substantiating your position. All you've done is define "level" within the context of RET, and "explained" the consequences of tilting a spirit level. Meanwhile, your misunderstanding is in understanding how it happens, not that it does.

All of the quotes directly addressed, how it happens… I know exactly how the bubble moves… it moves when an external force is applied to it, that is the point the refences make and that make your calculations irrelevant because they are based on

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Knowing this, we can apply basic classical mechanics to estimate the time the bubble would take to traverse the 2.5cm tube if this, and nothing else, were the factor responsible for the bubble's movement.

Your calculations are based on gravity and nothing else working on the level, but as I pointed, gravity is not what moves the bubble. Gravity is what determines where the bubble lands when it is stationary. Your calculations have nothing to do with anything, because it is external force…something other than gravity that actually makes the bubble move.
And the fact that the bubble moves by external force, is the key issue here.  With gravity, when you change the position of the spirit level, the bubble moves because the relative gravitational force changes.  With UA, when you move the level, there shouldn’t be any change in the relative force applied so there should not be any movement to the bubble. 

Not only are your calculations irrelevant, they are also wrong. It is the sensitivity of the level which determines how “fast” the bubble moves.  And the sensitivity is determined by the radius of the vial and to a lesser extent, the length of the level.  Without taking those into account, your calculations are meaningless. They don't even take the most important factors into account.

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The sensitivity of the vial determines how quickly the bubble moves when one end of the spirit level is lifted… Higher and lower sensitivity is achieved by changing the shape of the vial.

http://www.hultafors.com/about-our-products/spirit-levels-a-higher-level/what-is-a-spirit-levels-sensitivity/

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Statements like "fluids are more sensitive to gravitational pull than solids" only serve to further illustrate your inability to understand simple physics, and that's long before we even start discussing FET

Yes, liquids are more sensitive to gravity. Although gravity acts on equal amounts of mass the same way, gravity acting on 1 kg of solid may not be capable of changing its shape or move, whereas the same force on 1 kg of liquid may cause it to flow.

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As always, I suggest an experimental approach if you want to broaden your understanding. Take a spirit level and try using it in a moving elevator, particularly as it accelerates and decelerates. Observe its impact (or lack thereof) on the bubble until you've reached your conclusions.

I know what would happen in an accelerating elevator.  The bubble will always be at the highest level of the vial, but unless I am holding it level, it will not be in the middle.  What's your point? 

Oddly enough, I have the opportunity to “experiment” with levels on a regular basis.  Just did this weekend when we were camping and trying to level the camper.  The battery was dead on the drill so we had to jack it up manually.  The bubble didn’t move at all for about ten minutes and then with one turn of the jack jumped immediately from hardly visible on the left side to directly in the middle.  That’s because we have crappy level.  By the logic of your calculations, and your lack of understanding of why a bubble moves in a spirit level, I guess if we sat there and waited long enough, the bubble would have just moved on its own and the camper would have levelled itself through UA.

And notwithstanding everything I have said, you still have not explained how UA could be responsible for moving the bubble in a spirit level.  Before answering that, keep in mind that the bubble will always migrate to the highest level of the vial, but the highest level is the middle only when it is level.  How does UA act upon a spirit level in such a way that it causes the bubble to move to the middle?

Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 16, 2019, 03:51:14 PM
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The difference in gravity between two sides of a non-level spirit level are far too small to have an effect here

That makes no sense.  If the difference in gravity between two sides of a non-level spirit level were too small to have an effect, then how do you know it is not level?  Something is effecting it enough to show that its not level, and if a spirit level works by gravity then it stands to reason that that "something" is gravity.

When it is not level, what force is keeping the bubble from migrating to the middle? 

Not to mention the fact that NASA, manufacturers and people who use spirit levels as professionals disagree with you. 
Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 16, 2019, 09:36:31 PM
A spirit level does work because of gravity, but that's not what makes the bubble rest in the middle.
If the level is...level then the force of gravity would be the same across the liquid. That's what makes "water find its level".
But why would the bubble be in the middle? That's because the tube is slightly curved so the bubble rests in the middle.
If the level is at an angle then the highest point is no longer in the middle of the tube so the bubble moves.
It's not because a difference in gravity from one side of the level to the other.
This is how I understand it working:

(https://i.ibb.co/0rxFTvQ/Spirit-Level.jpg)

When the level is level the highest point of the tube is in the middle so that's where the bubble goes.
When the level is tilted the highest point of the tube isn't in the middle so the bubble is to one side.

Obviously the curve is exaggerated in that diagram.

This is because of the force of gravity but if the force was replaced by the force of UA then why wouldn't it work just the same?
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 16, 2019, 10:49:10 PM
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When the level is level the highest point of the tube is in the middle so that's where the bubble goes.
When the level is tilted the highest point of the tube isn't in the middle so the bubble is to one side.

Obviously the curve is exaggerated in that diagram.

This is because of the force of gravity but if the force was replaced by the force of UA then why wouldn't it work just the same?

The point that you both seem to be missing is that gravity is not what makes the bubble move...it is what determines where the bubble lands when the level is stationary.  In the RE model, gravity is what determines that the bubble lands at the highest point of vial.  Why would UA do that?  How does UA maintain the bubble in the middle?

And for the record, I am not saying that it wouldn't, I just don't see how it would and so far Pete has only attacked anything that I have said and deflected answering the question.

Try this as a thought experiment.

Imagine a spirit level at an angle accelerating upwards at an angle at the constant rate of UA.  What happens to the bubble?  Nothing.  It will float at the top of the vial, but will never move to the middle.  That would be true of both UA and gravity.

Then imagine accelerating the low end at a faster rate than UA  What happens to the bubble?  It moves to the middle. 

Then imagine returning the low end to the original rate of acceleration (remember again this is a thought experiment  ;))  With gravity, once you have it level, it stays that way until you move it. Once you move it and gravity determines where the bubble falls, it stays there. But what happens with UA?

One of two things...the low end falls again which would indicate that in order to maintain level a force greater than UA is required.  How can that be?

Or it remains level.  What causes it to remain level?  The only thing I can think of is that because the whole thing is accelerating at the same rate,  the UA force is equal along the whole spirit level and maintaining the bubble in the middle.

Two problems with this. First, if that is true, it is no longer analogous to gravity, according to Pete, because in the RE model "level" doesn't mean that the force of gravity is equal across the whole spirit level.  Something else is at work in both models apparently and so far, I haven't been offered any viable alternatives.

Secondly, if equal UA force across the whole spirit level is what maintains it at level, does that mean when it wasn't level, the force was not equal? How can that be if UA is a constant, consistent force that effects everything equally at all times?

Do you see the problem?  I hope that we can all agree at least that in order for the bubble to land in the middle when the level is tilted, you have to move the level.  In the RE model it lands in the middle and stays there because you have changed the level of gravitational pull across the length of the level and made it equal.  In the UA model, you aren't changing the level of “gravitational” pull across the length of level and making it equal...because it already was equal.

Pete wants to have it both ways.  Gravity and UA are analogous but one is a constant consistent force that effects everything equally at all times regardless of position or location and one is not a constant consistent force whose effect on anything is dependent on location and position.

That is not what analogous means.
Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 17, 2019, 07:13:08 AM
The point that you both seem to be missing is that gravity is not what makes the bubble move...it is what determines where the bubble lands when the level is stationary.
We're not "missing" it - you're just wrong when you claim it. Gravity causes the liquid to move, which in turn moves the bubble. Sure, you can apply an external force to briefly move the bubble out of its place, but gravitational forces will soon push it back into equilibrium. That state of equilibrium is the only thing that matters here. A spirit level is largely useless when it's not stationary, save for a few bizarre edge cases.

Two problems with this. First, if that is true, it is no longer analogous to gravity, according to Pete, because in the RE model "level" doesn't mean that the force of gravity is equal across the whole spirit level.
This isn't a problem - the difference you're fixating on is imperceptibly tiny. I already explained to you just how tiny it is, and why it's impossible for it to be of significance here.

But hey, if we're fixating on tiny differences - since the level is straight in shape and a Round Earth is curved, it is impossible for all points of the spirit level to be equidistant from the Earth's centre of gravity. Therefore, the gravitational forces will not be equal across the whole spirit level. Of course, this is of no significance, but it's yet another way in which your claim fails to maintain consistency with RET.

Something else is at work in both models apparently and so far, I haven't been offered any viable alternatives.
I already pointed out you ignored celestial gravitation, but I still don't think that will be very useful to you when you're so confused about mainstream physics. You can't successfully challenge either model without understanding it.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 17, 2019, 11:42:19 PM
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This isn't a problem - the difference you're fixating on is imperceptibly tiny. I already explained to you just how tiny it is, and why it's impossible for it to be of significance here

The difference I am fixated on is the difference between where the bubble is before you move the level and the where the bubble lands after you move the level.  If the difference is visible, then obviously the change is perceptible

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I already pointed out you ignored celestial gravitation

Celestial bodies are in motion and would create a fluctuating level of gravitational force, like the moon on the ocean.  When a level is level at high tide, and it is not moved in the meantime, it is still level at low tide.

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But hey, if we're fixating on tiny differences - since the level is straight in shape and a Round Earth is curved, it is impossible for all points of the spirit level to be equidistant from the Earth's centre of gravity

It's not impossible at all. Take a look at the attachment.


Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 18, 2019, 07:10:57 AM
The difference I am fixated on is the difference between where the bubble is before you move the level and the where the bubble lands after you move the level.  If the difference is visible, then obviously the change is perceptible
I already explained to you why your hypothesis is incorrect. If the difference in magnitude of gravitational force was what causes the bubble's displacement, and we assume RET is correct, it would take at least 13 minutes for it to settle. This does not occur in reality. Either RET is wrong or you're mistaken. Since an explanation that's consistent with RET is readily available, I propose that you're mistaken.

Once again, what's being contested is not that spirit levels work. They do. The problem is that you don't have a clue about why they work, and refuse to accept an explanation or to test your hypothesis.

Oh, and since I apparently missed this before:

It will float at the top of the vial, but will never move to the middle.
The "top of the vial" is "the middle". It is impossible for the bubble to simultaneously float to a position and not do so.

The tube of a spirit level is curved. That's why it works.

It's not impossible at all. Take a look at the attachment.
You were talking about the gravitational force across the whole spirit level, not two points on the spirit level. Swing and a miss.
Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 18, 2019, 08:56:22 AM
In the RE model, gravity is what determines that the bubble lands at the highest point of vial.  Why would UA do that?  How does UA maintain the bubble in the middle?
OK. The key thing is why does water "find its level"?
It's because of gravity.
Let's think about why a ball rolls down a hill.
There are two forces acting on it:

(https://i.ibb.co/1KN4ZNH/Ball-Rolling.jpg)

The downward arrow is gravity, the arrow pointing up the slope is friction.
A component of the downward gravity force acts down the slope, if that force is bigger than the friction force then the ball rolls, otherwise it doesn't.
The ball will roll until the forces are in balance. If the ball is on a level then the only force is gravity, as that is acting perpendiclar to the surface it's on there is no force sideways so it doesn't move. Gravity pulls the ball down, the surface it's resting pushes back up with an equal and opposite force (assuming a solid surface) so the ball is stationary.

Newton's first law - an object will remain at rest or moving at a constant velocity unless acted on by a force.

Water is a liquid. You can think of it as a jumble of balls, molecules, and the fact it's a liquid means the bonds between them are not strong and the molecules can move past one another.

This means that if you tip a container full of liquid you are effectively causing a slope so the same as above happens. The molecules tumble down the slope until the slope levels out and there is no more sideways force acting on them. I'm probably simplifying a bit there but this is why liquid "finds its level", the more viscous a liquid is the longer it will take to settle as the molecules move past one another more slowly.

If the tube in a spirit level was completely cylindrical then there would be no bubble, there'd just be a line of air at the top. The bubble is caused by the curve of the tube as I've shown above. If you tilt the tube the water stays level and because of the curve the bubble moves to the "top" of the inclined tube.

The cause of all this is the force of gravity pointing downwards.
If you replace the force of gravity by a force due to acceleration the same thing would happen. The whole premise of the equivalence principle is that if you're in a stationary lift on earth or a lift in zero g accelerating upwards at 9.8m/s2 you wouldn't be able to tell the difference. Both cause you and everything else to experience a downwards force. That means if you jump then you fall back down and water will find its level - and that's what makes a spirit level work.
Title: Re: Spirit Levels on a Flat Earth
Post by: totallackey on September 18, 2019, 12:07:02 PM
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But the force of gravity on either end is the same on both ends too, so what's the difference?
I think this would work fine with UA.

The force of gravity is the same on both ends only if it is level.  The reason the bubble migrates to the low end is because the force of gravity is stronger on the low end.  That is how a spirit level works...the bubble in the middle indicates that the gravitational force is equal across the length of the spirit level. 

With gravity, when the bubble is not in the middle, it indicates an unequal gravitational force across the length of the spirit level. With UA, then, when the bubble is not in the middle, that would mean an unequal force created by acceleration across the length. But if both ends are accelerating at the same rate, how can that be?
I don't understand this...

Are you claiming the top of any body of water is not being held in place by the same force that is holding the bottom of the body of water in place? Would not the top of the body of water be experiencing more force in order to keep it in place?
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 18, 2019, 03:01:04 PM
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The cause of all this is the force of gravity pointing downwards.
If you replace the force of gravity by a force due to acceleration the same thing would happen. The whole premise of the equivalence principle is that if you're in a stationary lift on earth or a lift in zero g accelerating upwards at 9.8m/s2 you wouldn't be able to tell the difference. Both cause you and everything else to experience a downwards force. That means if you jump then you fall back down and water will find its level - and that's what makes a spirit level work.

I don't disagree with any of that this, but you are missing the point.  The question is why is there no difference?.  The force of gravity on a spirit level depends on its position and location. The reason the bubble moves from off center and lands center when you move it is because when you move the level you are adjusting or "realigning" how the force of gravity is acting on the vial. The force of gravity on the vial has changed.  How gravity is effecting the vial is different because its location is different.

The force of UA upon a spirit level does not depend upon its position or location. The force of UA is constant and consistent on everything at all times.  It never changes.  When you move the spirit level, you are not adjusting or "realigning" how the force of UA is acting on the vial. How UA is effecting the vial is no different just because its location is different. The force of UA on the vial before you move the level is exactly the same.as the force of UA on the vial after you move the level.  The force of UA on the vial never changes no matter where it is at or what position it is in so why does moving the spirit level change where the bubble lands?

Sorry to keep repeating, but it is the central point to the issue and everybody just seems to ignore it.

The changed force of gravity after you move the position of level is why the bubble lands in the middle.  There is no change in the force of UA after you move the position of the level, so there is no reason (that I can think of) that UA should be responsible for the bubble landing in the middle.
Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 18, 2019, 03:19:30 PM
You keep restating your mistake over and over. No one's ignoring it. We told you time and time again why it's wrong.

The significant change is in direction (relative to the spirit level's horizontal plane), not magnitude. The change in direction is analogous between the two models. The change in magnitude is irrelevant (but also analogous thanks to CG). There is no difference because, by definition, the two models are indistinguishable in this context.

Stop saying the same thing over and over and work on understanding what I and AATW have explained to you.
Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 18, 2019, 04:06:21 PM
The question is why is there no difference?.

Because gravity is a force acting downwards. By "downwards" I mean relative to your position, assuming you are standing up.
It's actually towards the centre of mass of the earth and on a globe earth downwards is relative to your position, but to all intents and purposes gravity acts downwards.
Were the earth flat, there was no gravity and it was UA creating the force we call gravity then that force would act downwards and be equivalent.
The headline is both produce a force which acts in a downwards direction relative to your position.

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The reason the bubble moves from off center and lands center when you move it is because when you move the level you are adjusting or "realigning" how the force of gravity is acting on the vial. The force of gravity on the vial has changed.  How gravity is effecting the vial is different because its location is different.

Well, there would be a very slight difference because one end is higher than the other but that difference is so trivial that it's not what causes the bubble to move. Pete has done the maths for you.
The real difference is that the spirit level is no longer parallel to the ground so the force of gravity is no longer perpendicular to the tube - again, see my diagrams.
You have changed the orientation of the tube, the level of the liquid is still parallel to the ground because of the downward force of gravity but because the tube is not level the bubble is now off centre because the top of the tube is not at the centre.
This is true whether the force is caused by gravity or UA.

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Sorry to keep repeating, but it is the central point to the issue and everybody just seems to ignore it.

No-one is ignoring you but Pete actually does have a good grasp of physics - better than me, I think. And he is right here.
It's not the changed force of gravity, it's the changed orientation of the tube. The force acting downwards remains constant whatever is causing the force.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 18, 2019, 05:47:25 PM
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You were talking about the gravitational force across the whole spirit level, not two points on the spirit level. Swing and a miss.

If two points on a straight line are equal distance from a third point, all a points are.  It's inherent in the definition of "straight"., but I've filled it in on a new attachment for your benefit.

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The significant change is in direction (relative to the spirit level's horizontal plane), not magnitude.

In the RE model, a change in direction results in a stronger gravitational pull.  The lower something sits, the stronger the pull. So if lowering one end of the level causes the bubble to visibly move,  the change is gravitational force is perceptible.

But if you want to continue arguing that UA and gravity are analogous, and that "level" with gravity does not mean that that force of gravity is equal across the level, that is fine with me.

That just means that "level" with UA does not mean that that the force of UA is equal across the level.  Congratulations, you just blew a big fat hole in the whole UA theory which requires UA to be constant and consistent.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 18, 2019, 08:15:25 PM
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Were the earth flat, there was no gravity and it was UA creating the force we call gravity then that force would act downwards and be equivalent.
The headline is both produce a force which acts in a downwards direction relative to your position.

The point is that it would never change.  So there would be no reason for something to change due to its effects.  Something  doesn't move unless some force greater than what is already working on it causes it to move.  The UA force always stays the same, there is the same amount of force on the level before you move as there is after you move it, so there should be no reason that UA is what caused the bubble to land in the middle.


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Well, there would be a very slight difference because one end is higher than the other but that difference is so trivial that it's not what causes the bubble to move. Pete has done the maths for you.

Nobody is saying that the gravitational pull between the low end and the high end is what makes the bubble move.  External extra force is what makes the bubble move.  The level of gravitational force is what determines where it lands after you move it.  I have made that same point multiple times.  At any rate, the difference between the low end and the high end is significant enough to keep the bubble on the low end and prevent it from moving.  That is not "trivial"

Pete's math is irrelevant. It is based on the assumption that gravity (and only gravity) is moving the bubble in a stationary vial. It is based on the premise that I am arguing that it is the difference in gravitational pull between the low end and the high end is what makes the bubble move, but as explained above, that is not, nor has it ever been my position. If the vial is stationary and only gravity is working on it, of course bubble is not going to move. The gravitational force remains the same so there is no reason it should. The movement of the bubble I am talking about is the difference between where the bubble begins and where it lands after you move it..  And it makes no sense to say that movement is “trivial” when it is obviously enough to make the bubble move. 

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You have changed the orientation of the tube, the level of the liquid is still parallel to the ground because of the downward force of gravity but because the tube is not level the bubble is now off centre because the top of the tube is not at the centre
This is true whether the force is caused by gravity or UA
.

How does UA "know" what center is"?  What is it about UA that makes it able to detect when the top of the tube is at the center? 

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The force acting downwards remains constant whatever is causing the force.

No, gravitational force is not “constant” It varies depending on location and position. Gravitational force gets stronger the closer you get to the center of the earth. That’s Physics 101 and there is no reason to think that same concept would not apply to a level when you move it in a direction closer the center of the earth. It is subject to the same gravitational laws as everything else.  And again, it makes no sense to say that the change in gravitational force is “trivial”, when you can clearly see the that the bubble moves when you position it differently.

In the RE model, level is defined as when all points are perpendicular to gravity. How is it defined in the FE model?  Can someone please complete this sentence...With UA, something is level when.....???  That is all I am looking for. What does level mean with UA? 

Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 18, 2019, 09:05:48 PM
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The real difference is that the spirit level is no longer parallel to the ground so the force of gravity is no longer perpendicular to the tube - again, see my diagrams.

I get all that.  The bubble will always seek the highest point of the vial, but only when it is level will the highest point be in the middle.  I understand that perfectly. But why does the bubble seek the highest with UA?  In the RE model, it seeks the highest level because the gravitational pull is equal. And it is only equal because you have changed the orientation.

Is that the same with UA...it seeks the highest level because the UA force is equal and it only becomes equal when it is in the "correct" orientation?  If so, that begs the question was the UA force unequal before it was in the correct orientation?

That is the question Pete does not want to answer.
Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 19, 2019, 11:54:33 AM
If two points on a straight line are equal distance from a third point, all a points are.  It's inherent in the definition of "straight".
No. That's the definition of a "circular arc". Instead of drawing lines of different lengths and marking them as "4.25in", grab a ruler and draw a few points equidistant from a central point.

In the RE model, it seeks the highest level because the gravitational pull is equal. And it is only equal because you have changed the orientation.
This continues to be incorrect. Saying it many times won't make you less wrong. In case you forgot - if you were right about this, and the change in magnitude was the significant factor, the process of the spirit level reaching equilibrium would take at least 13 minutes. It does not do that.

If so, that begs the question was the UA force unequal before it was in the correct orientation?
That's not what "begging the question" means. Also, once again, the significant change here is that in direction, not in magnitude.

I also answered your question multiple times, despite pointing out that it's inconsequential: you're looking for celestial gravitation.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 19, 2019, 02:16:28 PM
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No. That's the definition of a "circular arc". Instead of drawing lines of different lengths and marking them as "4.25in", grab a ruler and draw a few points equidistant from a central point.

I didn’t draw anything.  I used an editing program that automatically measures.  If any two points on a straight line are equal distance from a third point, then by definition all points in between are also equal.  If that were not the case, at least one point in between would have to be higher or lower than the initial points…and it would no longer be a straight line.  Look at the most recent iteration.  That line does not look like an arc to me.   Feel free to measure the distances yourself.  It should be easier to do when the exact endpoints are visible.

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This continues to be incorrect. Saying it many times won't make you less wrong. In case you forgot - if you were right about this, and the change in magnitude was the significant factor, the process of the spirit level reaching equilibrium would take at least 13 minutes. It does not do that.

So your calculations show that when an eternal force is applied to a level, which causes the bubble to move, it takes 13 minutes for the bubble to stop moving?  Is that what your calculations show?
Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 19, 2019, 02:59:21 PM
The UA force always stays the same, there is the same amount of force on the level before you move as there is after you move it

That is also true with gravity. What has changed is the orientation of the tube

The level of gravitational force is what determines where it lands after you move it.

The direction of the gravitational force is what determines where it lands.

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The movement of the bubble I am talking about is the difference between where the bubble begins and where it lands after you move it..  And it makes no sense to say that movement is “trivial” when it is obviously enough to make the bubble move.

This and your comment that "why does the bubble seek the highest with UA?" makes me think maybe your error is you're too fixated on the bubble moving. It's not really the bubble that moves, it's the liquid. The bubble is simply the part of the tube the liquid isn't in. As I said before were the tube straight there wouldn't be a bubble, there would just be a line of air. It's not that the bubble moves to the top, more that the liquid moves to the bottom, The bubble is simply the bit where the liquid isn't. It moves as a consequence of the liquid moving.

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How does UA "know" what center is"?  What is it about UA that makes it able to detect when the top of the tube is at the center?
UA doesn't know anything, nor does gravity. Both simply produce a force which (for the purpose of this conversation) acts in a downwards direction.
When you move the tube it's not the gravity (or UA) which changes, it's the orientation of the tube. Again, see my diagrams. The liquid is pulled downwards, the surface of the liquid forms a straight line - that straight line is perpendicular to the force pulling the liquid down.

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No, gravitational force is not “constant” It varies depending on location and position. Gravitational force gets stronger the closer you get to the center of the earth. That’s Physics 101

It is but irrelevant for the purpose of this discussion. What's relevant is that gravity points downwards. As does the force caused by UA in FET

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In the RE model, level is defined as when all points are perpendicular to gravity. How is it defined in the FE model?  Can someone please complete this sentence...With UA, something is level when.....???  That is all I am looking for. What does level mean with UA?
With UA, something is level when all points are perpendicular to the force created by UA. UA accelerates the earth upwards, the force points downwards. As it does with gravity. Yes yes, technically it's towards the centre of mass of the earth but that is to all intents and purposes downwards.
Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 19, 2019, 03:19:19 PM
I used an editing program that automatically measures
I don't care how you did it - you're contradicting basic geometry. Fix it. The fact that you're spitting out PDFs out of Nitro Pro and that you can't even center your lines properly does not make you look better - it makes you look worse.

For the avoidance of doubt - a set of all equidistant points from another point, for a given distance, is a circle (https://en.wikipedia.org/wiki/Circle). A subset of that is a circular arc. Neither of those are straight. Therefore, your claim that a straight line will have all its points be equidistant from another point cannot be true.

So your calculations show that when an eternal force is applied to a level, which causes the bubble to move, it takes 13 minutes for the bubble to stop moving?  Is that what your calculations show?
No. I already told you what they show.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 19, 2019, 03:42:43 PM
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With UA, something is level when all points are perpendicular to the force created by UA. UA accelerates the earth upwards, the force points downwards. As it does with gravity. Yes yes, technically it's towards the centre of mass of the earth but that is to all intents and purposes downwards

Why is that true?  The amount of UA force on the level is the same whether it is perpendicular or not. 
Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 19, 2019, 04:03:49 PM
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With UA, something is level when all points are perpendicular to the force created by UA. UA accelerates the earth upwards, the force points downwards. As it does with gravity. Yes yes, technically it's towards the centre of mass of the earth but that is to all intents and purposes downwards

Why is that true?  The amount of UA force on the level is the same whether it is perpendicular or not.
It's true because of what level means, or rather what the consequence of something being on a level surface is.
I showed this above:

(https://i.ibb.co/1KN4ZNH/Ball-Rolling.jpg)

Why does the ball roll down the slope? Because the force acts downwards.
The surface the ball is on is not perpendicular to that force. That means there is a component of the force acting down the slope.
If that force is greater than the friction force then the ball will roll.
If the ball was on a level - I'm defining that as perpendicular to the direction of the force acting downwards - then because the force is perpendicular to the surface the ball is on there is no sideways component of the force. So the ball remains stationary, assuming the surface the ball is on is solid and able to bear the weight of the ball.

Yes?

Now, notice above I haven't used the term gravity or UA. I've just said there's a force acting downwards.
The mechanism which causes that force is left as an exercise to the reader...
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 19, 2019, 04:14:53 PM
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I don't care how you did it - you're contradicting basic geometry. Fix it. The fact that you're spitting out PDFs out of Nitro Pro and that you can't even center your lines properly does not make you look better - it makes you look worse.

When two points on a straight line are equal distance from a third…all points in between are also equal distance.  A circle is when all points are equidistant on a curved line.  A given point can be equidistant from points on either a straight or curved line and I specifically said “straight line”

And for the avoidance of doubt...Circle:  noun 1a closed plane curve consisting of all points at a given distance from a point within it called the center. Equation: x2 + y2 = r2.n. 

A straight line is neither a closed plane or a curve.

Arc: Geometry. any unbroken part of the circumference of a circle or other curved line

2 the portion of a plane bounded by such a curve.

Again...that word curve.

www.dictionary.com


If you don’t like how I did it, I’d be happy to look at something you have drawn up.

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No. I already told you what they show

Yes you did.  You mentioned that they show the rate of movement when nothing but gravity is working on the level.  But since I have never suggested that it is only gravity that works on the level, your 13 minutes is meaningless…and by the way, when only gravity is working on something…it doesn’t move at all…so even your 13 minutes is wrong.
Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 19, 2019, 04:41:45 PM
When two points on a straight line are equal distance from a third…all points in between are also equal distance.
Nope. Once again, I invite you to test your hypothesis with a ruler.

You're doing an excellent job illustrating my points about RE zealots, by the way.

You mentioned that they show the rate of movement when nothing but gravity is working on the level.
Perhaps unsurprisingly at this point, that's not at all what I said. You're welcome to re-read my explanation (https://forum.tfes.org/index.php?topic=15343.msg199499#msg199499) at your leisure, including a description of how you can verify your hypothesis experimentally.

But since I have never suggested that it is only gravity that works on the level
Awesome, let's hear it. What other forces "work on the level" when it's stationary relative to the ground? Choose whichever orientation you'd like.

…and by the way, when only gravity is working on something…it doesn’t move at all…
That's "falling" you're talking about. You're saying that objects falling is not a thing that happens.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 19, 2019, 05:06:13 PM
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Perhaps unsurprisingly at this point, that's not at all what I said. You're welcome to re-read my explanation at your leisure, including a description of how you can verify your hypothesis experimentally.
I believe what you said was...

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if this, and nothing else, were the factor responsible for the bubble's movement .

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Awesome, let's hear it. What other forces "work on the level" when it's stationary relative to the ground? Choose whichever orientation you'd like.

I specifically said, on multiple occasions and in multiple different ways…that it is not gravity that makes the bubble move.  It is gravity that determines where it lands.  And that it takes external force on the level to move bubble.  Once the bubble has landed and is stationary, then gravity holds it where it lands and is the only force impacting it. But I never suggested that gravity is what makes the bubble move when it is stationary on the ground. 

Specifically, I said
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I have no idea what those calculations are supposed to prove. Gravity doesn't move the bubble at all.  Gravity determines where it falls when it is stationary and not subject to any other force.  Have you ever even used one?  An external force must be applied to move the bubble.
Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 19, 2019, 05:17:05 PM
I believe what you said was...

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if this, and nothing else, were the factor responsible for the bubble's movement .
Indeed. Of course, now you need to read the context before to remind yourself what "this" is.

I specifically said, on multiple occasions and in multiple different ways…that it is not gravity that makes the bubble move.
The question you were just asked concerns what you think does cause it to move, not what doesn't.

But I never suggested that gravity is what makes the bubble move when it is stationary on the ground.
Yes, that's part of the problem. ;)
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 19, 2019, 10:42:51 PM
Here is the context
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To drive the point home, you can use something like https://www.vcalc.com/wiki/KurtHeckman/Gravity+Acceleration+by+Altitude to compare the value of g on the round Earth's surface to the value of g 2.5cm off the ground - the most generous case for what you propose. You will notice that the difference is "results offormula for difference between high and low level"..(it wouldn't let me insert the image). Knowing this, we can apply basic classical mechanics to estimate the time the bubble would take to traverse the 2.5cm tube if this, and nothing else, were the factor responsible for the bubble's movement.

“This” refers to  results of formula for difference between high and low level"..( …the difference between the gravitational on the low end and high of the level.  So when you refer to “it” it implies that I am suggested that the gravitational difference is what moves the bubble, even though I never said that. I don't see how adding "context" changes my original comment.

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The question you were just asked concerns what you think does cause it to move, not what doesn't.
And I answered it when I said…
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And that it takes external force on the level to move bubble.
in response to the question.

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Yes, that's part of the problem.

Only for you, because apparently you and AATW have both been operating on the misunderstanding that I had suggested that gravity is what makes the bubble move when it is stationary on the ground, despite repeating multiple time that was not what I said.

That misunderstanding conveniently allowed you to deflect from the actual argument I have been making all along.  Which is...

The bubble in the level will always seek the highest point of the tube.  The highest point is only in the middle when level.  In the RE model, when you change the position, the bubble will land according to the gravitational pull.  If it is equal, it will land in the middle.

In the FE model, when you change the position, does the bubble land according to the force of UA?  If it does, the bubble should land in the exact same place it was before you moved the level… because the force of UA should be the same.
 
With gravity, the only reason that moving the level more horizontal causes the bubble to land in the middle is because you are “equalizing” the gravitational force across the level. Moving the level more horizontal with UA doesn’t do that.  The force of UA is always equal across the level so moving it horizontally shouldn’t have any effect…if the bubble is landing according to the degree of UA force.



Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 20, 2019, 07:18:07 AM
“This” refers to  results of formula for difference between high and low level"..( …the difference between the gravitational on the low end and high of the level. 
Thank you for correcting yourself. One down, $BIGNUM to go!

Only for you, because apparently you and AATW have both been operating on the misunderstanding that I had suggested that gravity is what makes the bubble move when it is stationary on the ground, despite repeating multiple time that was not what I said.
In RET, gravity is what moves the bubble once the level is stationary. The problem is precisely that you keep claiming the opposite.

Your assertion is that "an external force" is responsible instead. Which force, specifically? Name it, identify its source, and give us an idea of the magnitude and direction.

In the RE model, when you change the position, the bubble will land according to the gravitational pull.  If it is equal, it will land in the middle.
This continues to be false, and you already had it explained by two people, in a variety of ways. It is not the magnitude of gravity that changes (in any meaningful way for the purpose of this discussion), but the direction, relative to the level's horizontal plane.
Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 20, 2019, 09:01:31 AM
With gravity, the only reason that moving the level more horizontal causes the bubble to land in the middle is because you are “equalizing” the gravitational force across the level. Moving the level more horizontal with UA doesn’t do that.  The force of UA is always equal across the level so moving it horizontally shouldn’t have any effect…if the bubble is landing according to the degree of UA force.
Once more for the cheap seats: It's not the magnitude of the force which determines where the bubble ends up, it's the direction of the force.
That is true whatever the mechanism causing the force is.
I've explained this above and I reiterate you're focusing too much on the bubble. You need to understand that it's the liquid that moves.
The result of the liquid moving is the bubble does.

On earth the surface of a liquid will always be perpendicular to the force acting downwards on it. I have explained why above.
Otherwise the surface of the liquid would be sloping - no longer perpendicular to the force.
This would cause sideways forces which makes the liquid "level" again - I'm defining level as "perpendicular to the downwards force".
With a more viscous liquid you could see this happening.
Note that this doesn't happen in space, it only happens on earth because there is a downwards force acting on the liquid.

The mechanism which causes that downwards force is not relevant.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 20, 2019, 10:19:06 AM
Quote
This continues to be false, and you already had it explained by two people, in a variety of ways. It is not the magnitude of gravity that changes (in any meaningful way for the purpose of this discussion), but the direction, relative to the level's horizontal plane.

https://www.studocu.com/en/document/university-of-johannesburg/surveying-3b21/lecture-notes/surveying-3b-chapter-4-introduction-to-vertical-distance-measurement-leveling/3878251/view


Is that stated clearly and plainly enough for you to understand?

How about this?

Quote
The principle of operation is that the bubble will move to the highest point of the radius as gravity acts on the liquid inside the vial

Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 20, 2019, 10:25:44 AM
Yes, that's wonderfully simple. Now you just need to read it and take the information in. None of what you cited comes even close to substantiating your claims, and the specific quote you provided indicated that it is gravity that moves the bubble - the opposite of the claim you're supposed to be defending.

Perhaps unsurprisingly, it also states that "A Level surface (plane) is one which is normal to the direction of gravity at all points in its length." Compare and contrast to your own claim: "level" with gravity means that that force of gravity is equal across the level

Note how your source discusses the direction (as we did), and not the magnitude (as you're trying to). Note how it doesn't talk about any forces being "equal".

Your source also does a fantastic job of explaining why the line you were discussing cannot be straight - despite you insisting that it was the very definition of "straight".

Ultimately, the issue here is that you think we don't understand you, and that you just need to keep clarifying your meaning until it sinks in. We understand what you're saying, it's just that what you're saying is laughably wrong, and every single source you provided to date ended up flat out contradicting you. This discussion cannot meaningfully continue until you develop a basic understanding of physics (to understand how a spirit level works), geometry (to understand that circles are not straight lines, and the significance of a direction and magnitude of any given vector), and the English language (so that you stop taking sources that directly contradict you and present them as something that helps your case).


Also, you forgot to answer the question:

Your assertion is that "an external force" is responsible instead. Which force, specifically? Name it, identify its source, and give us an idea of the magnitude and direction.
:)
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 20, 2019, 10:49:52 AM
How about this?

Quote
The performance of the spirit level is governed by the geometrical relationship between the bubble and the two references. That is –
The first reference is an effect of gravity and the second one is a scale against which the bubble is read.

Translation: As the geometric relationship (the relative position to each other) between the level and  is what governs the performance of the level.  When you change the position of the level, it changes the way gravity acts on the level and determines where the bubble lands in reference to the scale.

https://gaugehow.com/spirit-level/

I will address your other comments in a bit, I need to get to work.







Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 20, 2019, 10:57:57 AM
Quote
Once more for the cheap seats: It's not the magnitude of the force which determines where the bubble ends up, it's the direction of the force.
That is true whatever the mechanism causing the force is

No matter what position the level is in, with UA it is still accelerating at the same rate and in the same direction.

Quote
The mechanism which causes that downwards force is not relevant.

That is correct.  It is the relationship between the level and the force that is relevant.   Moving the level makes no difference in the relationship between UA an the level, so moving the level should  have no effect on how it performs.
Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 20, 2019, 11:00:12 AM
No matter what position the level is in, with UA it is still accelerating at the same rate and in the same direction.
No - the direction relative to the spirit level does change. That's the whole point.
Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 20, 2019, 12:32:18 PM
No matter what position the level is in, with UA it is still accelerating at the same rate and in the same direction.

UA is still accelerating in the same direction. What has changed is the orientation of the level relative to that direction.

When you change the position of the level, it changes the way gravity acts on the level and determines where the bubble lands in reference to the scale.

Also correct. The level is no longer perpendicular to the direction of gravity, that changes the way gravity acts on it.

Moving the level makes no difference in the relationship between UA an the level, so moving the level should  have no effect on how it performs.

Oh dear. You were doing so well, too.
Dude, come on. You're nearly there...
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 20, 2019, 01:43:42 PM
Quote
No - the direction relative to the spirit level does change. That's the whole point.

The direction is always "up".

When the level is at 45 degree angle, the low end is accelerating up at 9.80665 m/s2 and the high end is accelerating up 9.80665 m/s2.  The low end is accelerating in the same direction and subject to the same amount of force as the high end and the bubble is not level.

When the level is at 90 degree angle the left side is accelerating up at 9.80665 m/s2 and the right side is accelerating up at 9.80665 m/s2.  The left side and the right side are accelerating in the same  direction and subject to the same amount force.  Why is the bubble in the middle at a 90 degree angle and not a 45 degree angle when in both cases, they are accelerating in the same direction and subject to the same amount of force?

Quote
Your assertion is that "an external force" is responsible instead. Which force, specifically? Name it, identify its source, and give us an idea of the magnitude and direction.

It could be any force....the wind or whatever, but in general it would be somebody physically moving it...see my references below.

Quote
Your source also does a fantastic job of explaining why the line you were discussing cannot be straight - despite you insisting that it was the very definition of "straight".

Ok, let's think about it for a minute.  I think we can safely assume the source would agree that the earth is round and I think we can also safely assume that the source would agree that a level is straight.

The source clearly says that "level" means that all points are equal distance from gravity, so it would follow that the source would also agree that a straight level can indicate all points an equal distance from gravity on a round earth.  It wouldn't make much sense for a surveyor to use a spirit level if that surveyor didn't believe that a straight level could indicate all points are equal distance from gravity if the earth is round.

Quote
In RET, gravity is what moves the bubble once the level is stationary. The problem is precisely that you keep claiming the opposite.
No, it isn’t the RET position that what moves the bubble once the level is stationary is gravity.  I have already offered several references to prove that, but here are some of the more clear ones again. 

Quote
When the left side is too high the bubble will sit on the right side of the graduation marks and vice-versa for the opposite side. Using this as a guide, you can now make the necessary adjustment to create a perfectly level project.
Translation: In order for the level the bubble, you have to adjust the level
https://www.home-dzine.co.za/diy/diy-spiritlevel.htm

Quote
If the bubble floats to the left, raise the right side, and vice-versa.
Translation: In order to move the bubble, you have to manually raise or lower the level.
https://everything2.com/title/Spirit+level

Quote
To counter this effect the end of the level nearer the mass must be tipped up to recenter the bubble. In other words, the level surface tips upward as one approaches the mass.
Translation:  You have to tip the level in order to center the bubble.
https://history.nasa.gov/SP-4211/ch11-4.htm

Quote
For example, if a bubble is off to the right, then your surface rises to the right. Conversely, that same surface could be described as sloping down to the left. It’s a matter of perspective. Adjust your area or the object as necessary and repeat until you get a level reading you desire.
Translation: You have to adjust the object you are leveling relative to the level for the bubble to read level
https://www.keson.com/how-to-read-a-spirit-level/

Quote
Now, looking at the vial which is at right angle to the base of the spirit level – if the bubble is between the marks, the surface is vertical. If the bubble sits outside the marks, move the level until the bubble is centrally placed.
That one really shouldn’t need any translation.
https://www.actavodirect.com/blog/how-to-use-spirit-levels/

Neither should the next one.
Quote
Where the bubble sits over or out of the graduation marks, adjust the spirit level to the left or right.
https://www.property24.com/articles/how-to-use-a-spirit-level/17759

Let me know if these are not enough.

Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 20, 2019, 01:46:17 PM
Quote
Oh dear. You were doing so well, too.
Dude, come on. You're nearly there...

I will simply repeat the question I asked Pete...

When the level is at 45 degree angle, the low end is accelerating up at 9.80665 m/s2 and the high end is accelerating up 9.80665 m/s2.  The low end is accelerating in the same direction and subject to the same amount of force as the high end and the bubble is not level.

When the level is at 90 degree angle the left side is accelerating up at 9.80665 m/s2 and the right side is accelerating up at 9.80665 m/s2.  The left side and the right side are accelerating in the same direction and subject to the same amount force and the bubble is in the middle.

When you move the level from 45 degrees to 90 degrees you have not changed the relationship between the UA force and the level relative to the direction it is moving or the amount of force on it.  It is always accelerating up at 9.80665 m/s2, always accelerating up at the same rate all the way across the level, and always subject to the same amount of force all across the level.  One end or side is not subject to any more force and is not accelerating at a faster rate, no matter the position of the level.

Why is the bubble in the middle at a 90 degree angle and not a 45 degree angle when in both cases, they are accelerating in the same direction and subject to the same amount of force?


Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 20, 2019, 02:50:49 PM
The direction is always "up".
There are only so many times I can say the same thing over and over.

The magnitude doesn't have any effect here.

The direction of the force, relative to the spirit level, is not always up. Not only because it changes, but also because "up" is meaningless in this context.

You lack the ability to understand fundamental maths and physics. This conversation will not proceed until you resolve that. You cannot meaningfully defend RET without understanding its basics.
Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 20, 2019, 03:06:05 PM
Why is the bubble in the middle at a 90 degree angle and not a 45 degree angle when in both cases, they are accelerating in the same direction and subject to the same amount of force?
In both cases the bubble is at the top of the tube. And that's because the water is at the bottom.
Again, it's not the bubble that moves, it's the liquid. The downward force acting on the liquid makes it "find its level", the surface of the liquid remains perpendicular to the force acting on it.
Try this diagram. It's the same as one I posted above but in this one I've drawn arrows which indicate the direction of the downward force acting on the level.

(https://i.ibb.co/zfSzG6Y/Level2.jpg)

The water stays at the bottom because of the downward force, that means the bubble stays at the top.
It's only when the level is at a 90 degree angle (to the downward force) that the middle of the tube and the top of the tube are in the same place.
That's how you know the tube is level.

Again, the source of the downward force is irrelevant.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 20, 2019, 04:45:40 PM
Quote
The water stays at the bottom because of the downward force, that means the bubble stays at the top
.

If the downward force is strong enough to keep the water on the bottom when it’s not level, why isn’t it strong enough to keep it on the bottom when it is level?  The downward force doesn’t change.

It is simple logic
Downward force @ 9.8m/s2  = water level at bottom
Water level at bottom=unlevel
Downward force=unlevel

Downward force @ 9.8m/s2  = bubble at top
bubble at top=level
Downward force=level
Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 20, 2019, 04:46:57 PM
If the downward force is strong enough to keep the water on the bottom when it’s not level, why isn’t it strong enough to keep it on the bottom when it is level?
It is.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 20, 2019, 05:04:55 PM
Quote
It is.

Sorry, I was in too big a hurry.  I meant to ask If the downward force is strong enough to keep the water on the bottom and the bubble uncentered when it is unlevel..why isn't it strong enough the keep the water on the bottom and the bubble uncentered when it is level?

The downward force is the same on the water, whether it is level or not.  So if that amount of force is sufficient to keep the bubble uncentered when unlevel, it should be sufficient to keep the bubble uncentered when it is level.
Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 20, 2019, 05:39:18 PM
Quote
It is.
why isn't it strong enough the keep the water on the bottom and the bubble uncentered when it is level?
How do you think the water can be at the bottom and it could be level and the bubble could be anywhere other than the centre?
Again, the bubble is just the bit where the water isn’t. If the water is at the bottom then the bubble is at the top. When it’s level the top is the centre, where else could the bubble be? ???
Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 20, 2019, 05:52:22 PM
I meant to ask If the downward force is strong enough to keep the water on the bottom and the bubble uncentered when it is unlevel..why isn't it strong enough the keep the water on the bottom and the bubble uncentered when it is level?
Once again, you're confused. The magnitude (or "strength", if you insist) of the force is irrelevant. It's the direction that matters.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 20, 2019, 07:19:20 PM

Quote
Once again, you're confused. The magnitude (or "strength", if you insist) of the force is irrelevant. It's the direction that matters.


If the downward force is enough to keep the bubble and/or water in whatever position it is in at 45 degrees, it should be strong enough to keep it at that same position at 90 degrees.

It is a basic principle of motion that a body at rest, which would include bubbles and water, will stay at rest unless some force acts upon it.  So when you move the move the level, the only way the bubble and water can move is if you are applying additional force over and above what was already impacting it which means you are not just changing the direction or orientation of the level when you move it.  Secondly, only an unbalanced force can change the direction of an object.  UA is a balanced force, so to change the direction, some additional force must be applied.

Which is completely consistent with both UA and gravity.  But as I suggested earlier, the question becomes what happens when you stop applying the additional force?
Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 21, 2019, 06:53:34 AM
Ok. Try this.

Take 2 beakers.
Half fill them with water.
Put one on a table and one in the freezer upright and wait till the water is frozen.

Take the beaker out of the freezer and put it on a table next to the on one which hasn’t been in the freezer.

Note how the level of the water and the level of the ice is parallel with the surface of the table (assuming the table is level and the beaker was level in the freezer).

Now tilt the two beakers.
What happens to the level of the water and the level of the ice?
Is it the same?
If it’s different, why is it different?

Understanding this is your key to understanding what happens in a spirit level when you change its orientation.

It’s not that an additional force is being applied, it’s that you have changed the orientation of the level with respect to the direction of the force acting on it.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 21, 2019, 04:57:36 PM
 1.   Level is when all points are normal to the direction of gravity across its length.

Quote
A level surface (plane) is one which is normal to the direction of gravity at all points in its length
https://www.studocu.com/en/document/university-of-johannesburg/surveying-3b21/lecture-notes/surveying-3b-chapter-4-introduction-to-vertical-distance-measurement-leveling/3878251/view


2.   Therefore, when a surface is not level, not all points are normal to the direction of gravity at all points in its length.

3.   When all points are not normal to the direction of gravity, the points experience differing degrees of gravitational pull because the normal force is always equal between gravity and the points in an object when the points in the object are normal to the direction of gravity.

Quote
In a simple case such as an object resting upon a table, the normal force on the object is equal but in opposite direction to the gravitational force
https://en.wikipedia.org/wiki/Normal_force


4.   Therefore, when you adjust a spirit level from unlevel to level, you are adjusting it from not normal to the direction of gravity to normal to the direction of gravity and from all points not being under the same gravitational pull to all points being under the same gravitational pull.

Now if UA is analogous to gravity, we should be able to just substitute the “gravity” for “UA”.  This is what we get.

1.   Level is when all points are normal to the direction of UA force across its length.
2.   Therefore, when a surface is not level, not all points are normal to the direction of UA force at all points in its length.
3.   When all points are not normal to the direction of the force of UA, the points experience differing degrees of UA force because the normal force is always equal between the UA force and the points in an object when the points in the object are normal to the direction of the UA force.
4.   Therefore, when you adjust a spirit level from unlevel to level, you are adjusting it from not normal to the direction of UA force to normal to the direction of UA force and from all points not being under the same UA force to all points being under the same UA force..

Which of those points is incorrect?


Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 21, 2019, 09:31:26 PM
Which of those points is incorrect?
Its point 3.
The orientation of the object or part of an object doesn't affect the magnitude of the gravitational force on it in any meaningful way.
It simply means the force acts in a different direction.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 21, 2019, 10:46:19 PM
Quote
Its point 3.
The orientation of the object or part of an object doesn't affect the magnitude of the gravitational force on it in any meaningful way.
It simply means the force acts in a different direction.

If the difference in gravitational pull among the points is enough to make the spirit level unlevel, eliminating the difference in gravitational pull is enough to make it level.  It is simple logic.

force in a different direction= level
level=all points equal gravitational force
force in a different direction=all points equal gravitational force



Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 22, 2019, 07:24:49 AM
There isn’t a difference in gravitational pull among the points. This is the point you are repeatedly failing to understand.
The only difference when you change the orientation of the level is the direction the force acts. The magnitude of the force remains the same at all points of the level.
There is a tiny, tiny difference because one end of the level is higher and thus further from the centre of mass of earth but that is not what causes the liquid to move. It’s the difference in direction the force is acting in. And that’s why the cause of the force doesn’t matter.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 22, 2019, 12:26:03 PM
Quote
There isn’t a difference in gravitational pull among the points

Yes there is. Again, it is simple logic.

Level= normal to the direction of gravity
Normal to the direction of gravity=equal gravitational pull
Level = equal gravitational pull

Unlevel= not normal to the direction of gravity
Not normal to the direction of gravity = unequal gravitational pull
Unlevel= unequal gravitational pull

If level means equal gravitational pull and unlevel means unequal gravitational pull, there is a difference in the level of gravitational pull between level and unlevel.
Title: Re: Spirit Levels on a Flat Earth
Post by: AllAroundTheWorld on September 22, 2019, 01:32:34 PM
If level means equal gravitational pull and unlevel means unequal gravitational pull, there is a difference in the level of gravitational pull between level and unlevel.
Indeed. If that’s what level means.
But that isn’t what level means.
You should know this.
You defined level correctly yourself above:

Level is when all points are normal to the direction of gravity across its length

Yes. That’s what level means. Changing the orientation of something which is level doesn’t mean the gravitational force becomes unequal, it just means the direction of the force is different. Still equal across the object, still the same magnitude as when the object was level just in a different direction, no longer normal to the object.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 22, 2019, 04:00:39 PM
Quote
Yes. That’s what level means. Changing the orientation of something which is level doesn’t mean the gravitational force becomes unequal

If you change the orientation from level to not level, that is exactly what it means.

You apparently don’t understand what the normal force is.  It is the force that opposes gravity.  When you are standing on the ground, gravity is pulling you down and the normal force of the ground is pushing you up. 

When something is “normal to the direction of gravity” it means that the normal force pushing it up is equal to the gravitational force pulling it down.
When you are standing normal to the direction of gravity, you don’t fall.  If you lean over far enough, eventually the gravitational force will be stronger than the normal force exerted by the ground and you fall down.

When a spirit level is level…when it is “normal to the direction of gravity”…the gravitational force on the bubble, which is pulling the bubble down, is equal to the normal force produced by the level, which is pushing it up.  If you tilt the level far enough, the gravitational force on the bubble becomes greater than the normal force produced by level…and the bubble “falls”.

In other words, saying that an object is level when all points are normal to the direction of gravity is just another way of saying that there is equal gravitational force on all points of the object. When something is not “normal to the direction of gravity” and is therefore not level is just another way of saying there the gravitational force is not equal.
Title: Re: Spirit Levels on a Flat Earth
Post by: garygreen on September 22, 2019, 05:00:23 PM
When a spirit level is level…when it is “normal to the direction of gravity”…the gravitational force on the bubble, which is pulling the bubble down, is equal to the normal force produced by the level, which is pushing it up.  If you tilt the level far enough, the gravitational force on the bubble becomes greater than the normal force produced by level…and the bubble “falls”.

imagine a spirit level in which the 'air bubble' is evacuated.  there is no air in the tube, only liquid and a small bubble of vacuum.  now there is nothing inside the bubble for gravity to act on.  it can only act on the liquid.  how do you expect the spirit level to behave?  will it still work?  why or why not?
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 23, 2019, 12:12:29 AM
Quote
imagine a spirit level in which the 'air bubble' is evacuated.  there is no air in the tube, only liquid and a small bubble of vacuum.  now there is nothing inside the bubble for gravity to act on.  it can only act on the liquid.  how do you expect the spirit level to behave?  will it still work?  why or why not?

What you are suggesting is a non-sequitur and it is impossible for any logical conclusion to follow from it.

The bubble is just the air left in the vial as a result of it being incompletely filled. The bubble is just the absence of fluid.  What you are asking is "imagine there is no absence of fluid in the vial".  If there is no lack of fluid in the vial, the vial is completely full and will not move at all because it would be constrained by the walls of the vial.
Title: Re: Spirit Levels on a Flat Earth
Post by: garygreen on September 23, 2019, 01:16:13 AM
Quote
imagine a spirit level in which the 'air bubble' is evacuated.  there is no air in the tube, only liquid and a small bubble of vacuum.  now there is nothing inside the bubble for gravity to act on.  it can only act on the liquid.  how do you expect the spirit level to behave?  will it still work?  why or why not?

What you are suggesting is a non-sequitur and it is impossible for any logical conclusion to follow from it.

The bubble is just the air left in the vial as a result of it being incompletely filled. The bubble is just the absence of fluid.  What you are asking is "imagine there is no absence of fluid in the vial".  If there is no lack of fluid in the vial, the vial is completely full and will not move at all because it would be constrained by the walls of the vial.

no i'm saying imagine that there are no particles of any kind in the bubble.  imagine that the vial has liquid and a small bubble of vacuum.  now there is nothing in the bubble for gravity to act upon.  does the spirit level still work?
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 23, 2019, 03:43:11 PM
Quote
no i'm saying imagine that there are no particles of any kind in the bubble.  imagine that the vial has liquid and a small bubble of vacuum.  now there is nothing in the bubble for gravity to act upon.  does the spirit level still work?

I know what you are asking and you are asking me to speculate on what "nothing" would do in a particular circumstance.  A bubble without anything inside of it is, literally, nothing. 

For the sake of argument, however, no the spirit level would not work. The bubble rises to the top because of gravity and if there is nothing for the gravity to work on, it will not rise to the top of the vial.  Where the top of the vial is completely dependent on the position of the level and the fluid has nothing to do with it.
Title: Re: Spirit Levels on a Flat Earth
Post by: ChrisTP on September 23, 2019, 04:04:32 PM
Quote
no i'm saying imagine that there are no particles of any kind in the bubble.  imagine that the vial has liquid and a small bubble of vacuum.  now there is nothing in the bubble for gravity to act upon.  does the spirit level still work?

I know what you are asking and you are asking me to speculate on what "nothing" would do in a particular circumstance.  A bubble without anything inside of it is, literally, nothing. 

For the sake of argument, however, no the spirit level would not work. The bubble rises to the top because of gravity and if there is nothing for the gravity to work on, it will not rise to the top of the vial.  Where the top of the vial is completely dependent on the position of the level and the fluid has nothing to do with it.
or the liquid falls the the bottom because of gravity, the bubble is just a lack of liquid. not really an entity of its own.
Title: Re: Spirit Levels on a Flat Earth
Post by: pricelesspearl on September 23, 2019, 04:21:21 PM
Quote
or the liquid falls the bottom because of gravity, the bubble is just a lack of liquid. not really an entity of its own.

Correct, I told him the exact same thing.  What he asking is....what would air do if there is not air in it? ::)
Title: Re: Spirit Levels on a Flat Earth
Post by: Pete Svarrior on September 23, 2019, 05:02:43 PM
Correct, I told him the exact same thing.
And yet, somehow, you reached a conclusion that's precisely opposite to "the exact same thing". If the bubble is just "a lack of liquid", then it does not matter whether it's air, helium, or vacuum.