The Flat Earth Society

Flat Earth Discussion Boards => Flat Earth Theory => Topic started by: edby on November 11, 2018, 11:45:23 AM

Title: Increased gravity at the poles?
Post by: edby on November 11, 2018, 11:45:23 AM
From the Wikipedia article on Clairaut's theorem:
Quote
https://en.wikipedia.org/wiki/Clairaut%27s_theorem Although it had been known since antiquity that the Earth was spherical, by the 17th century evidence was accumulating that it was not a perfect sphere. In 1672 Jean Richer found the first evidence that gravity was not constant over the Earth (as it would be if the Earth were a sphere); he took a pendulum clock to Cayenne, French Guiana and found that it lost 2 ½ minutes per day compared to its rate at Paris. This indicated the acceleration of gravity was less at Cayenne than at Paris. Pendulum gravimeters began to be taken on voyages to remote parts of the world, and it was slowly discovered that gravity increases smoothly with increasing latitude, gravitational acceleration being about 0.5% greater at the poles than at the equator.
How would FE theory explain this result? As usual there are two questions (i) whether the observation is correct and (ii) if correct, how would FE theory explain the difference in gravity?

This is different from the height effect, whereby gravity decreases with height. This is explained by Celestial Gravitation (https://wiki.tfes.org/Celestial_Gravitation). The Clairaut phenomenon, by contrast, is a surface effect, dependent only on latitude.
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 11, 2018, 09:38:39 PM
Firstly, in specific to your quote about the pendulum clock, it seems difficult to trust that a pendulum clock would maintain its constant rate when being moved and jostled over such a great distance.

Secondly, to address your point, the reason advanced by the wider Flat Earth movement for why there is more weight at the poles is due to two factors:

1. The atmosphere has weight, and atmospheric pressure "pushes down" on us.

See the following illustration:

(https://i.imgur.com/zfY80bZ.png)

2. The barometric pressure is higher at the poles

See  https://en.wikipedia.org/wiki/Polar_High

Quote
Polar High

The polar highs are areas of high atmospheric pressure around the north and south poles; the north polar high being the stronger one because land gains and loses heat more effectively than sea. The cold temperatures in the polar regions cause air to descend to create the high pressure (a process called subsidence), just as the warm temperatures around the equator cause air to rise to create the low pressure intertropical convergence zone.

Ergo, if there is more pushing pressure, due to the Polar Highs, we will weigh more at the poles.
Title: Re: Increased gravity at the poles?
Post by: edby on November 12, 2018, 09:21:38 AM
1. The atmosphere has weight, and atmospheric pressure "pushes down" on us.
2. The barometric pressure is higher at the poles

See  https://en.wikipedia.org/wiki/Polar_High
[…]
Ergo, if there is more pushing pressure, due to the Polar Highs, we will weigh more at the poles.
Interesting. This could easily be measured and tested. If my weight goes up and down with atmospheric pressure, we could draw up a scatter chart showing the correlation.

Doesn't this conflict with the standard 'scientific' view that weight goes down with pressure? This is why humans float in water, for instance.
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 12, 2018, 03:59:16 PM
I don't see why weight would go down with pressure. You are talking about buyancy and density of objects, which is a different subject.

Will a boulder feel more weight on the beach or on the bottom of the ocean?
Title: Re: Increased gravity at the poles?
Post by: Boots on November 12, 2018, 04:03:56 PM
A rock underwater will weigh 2/3 of what a rock on the beach weighs.
Title: Re: Increased gravity at the poles?
Post by: edby on November 12, 2018, 05:02:03 PM
I don't see why weight would go down with pressure. You are talking about buyancy and density of objects, which is a different subject.

Will a boulder feel more weight on the beach or on the bottom of the ocean?

Quote
https://www.soest.hawaii.edu/GG/ASK/weight.html
Would a person weigh more in a denser atmosphere than in a less dense atmosphere? Does the pressure exerted by a column of air cause changes in a person's weight?
 
Actually, a person would weigh less in a denser atmosphere. "Weight" is how much you push down on a scale - which is different from "mass" which is how much matter you contain (which wouldn't change). The formula is: weight= mass*(gravitational acceleration). The pressure exerted by a column of air is the same in all directions, so a heavy atmosphere does not have weight since it pushes just as much up as it does down. What makes your weight be less in a heavy atmosphere is the buoyancy effect - your volume is taking up space that would normally be taken by the heavy air, and the mass of the displaced air is subtracted from your mass when calculating weight: your weight=(your mass-displaced air mass)*(acceleration of gravity). Note that if the mass of displaced air is equal to your mass, you will weigh nothing (neutral buoyancy), and if you weigh less than the displaced air (as you do in water) you will float.

Dr. Fred Duennebier, Professor
Department of Geology and Geophysics
University of Hawaii, Honolulu
Title: Re: Increased gravity at the poles?
Post by: Bobby Shafto on November 12, 2018, 05:38:04 PM
I don't see why weight would go down with pressure.

I think the confusion stems from the erroneous belief that air pressure has a vector: i.e. "pushing down."

Air pressure is not measured like weight. It's not additive to weight as your proposed FET solution to the OP question presumes.

If the earth's atmosphere suddenly disappeared, you'd weigh the same. (Or, if have the ability to measure very precisely, you'd find your weight increased ever so slightly due to the loss of buoyancy.)
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 12, 2018, 06:04:37 PM
It is not an "FE belief":

http://www.weatherquestions.com/How_much_does_air_weigh.htm

Quote
How much does air weigh?

It might not seem like it, but air has weight. Anything with mass has weight, and we know air has mass because (for example) we can feel it when the wind blows. The total weight of the atmosphere exerts a pressure of about 14.7 pounds per square inch at sea level.
Title: Re: Increased gravity at the poles?
Post by: edby on November 12, 2018, 06:13:27 PM
http://www.weatherquestions.com/How_much_does_air_weigh.htm
The total weight of the atmosphere exerts a pressure of about 14.7 pounds per square inch at sea level.

Correct, and so it exerts that pressure on the bathroom scales even when no one is standing on them. When I now stand on them, the result is my additional weight, i.e. my weight in a vacuum.
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 12, 2018, 06:58:54 PM
I don't see why weight would go down with pressure. You are talking about buyancy and density of objects, which is a different subject.

Will a boulder feel more weight on the beach or on the bottom of the ocean?

Quote
https://www.soest.hawaii.edu/GG/ASK/weight.html
Would a person weigh more in a denser atmosphere than in a less dense atmosphere? Does the pressure exerted by a column of air cause changes in a person's weight?
 
Actually, a person would weigh less in a denser atmosphere. "Weight" is how much you push down on a scale - which is different from "mass" which is how much matter you contain (which wouldn't change). The formula is: weight= mass*(gravitational acceleration). The pressure exerted by a column of air is the same in all directions, so a heavy atmosphere does not have weight since it pushes just as much up as it does down. What makes your weight be less in a heavy atmosphere is the buoyancy effect - your volume is taking up space that would normally be taken by the heavy air, and the mass of the displaced air is subtracted from your mass when calculating weight: your weight=(your mass-displaced air mass)*(acceleration of gravity). Note that if the mass of displaced air is equal to your mass, you will weigh nothing (neutral buoyancy), and if you weigh less than the displaced air (as you do in water) you will float.

Dr. Fred Duennebier, Professor
Department of Geology and Geophysics
University of Hawaii, Honolulu

As it says in that quote: it does not equal out to be zero.

"Actually, a person would weigh less in a denser atmosphere."

Also:

"Note that if the mass of displaced air is equal to your mass, you will weigh nothing (neutral buoyancy), and if you weigh less than the displaced air (as you do in water) you will float."

And it follows form that if the mass weighs more than the displaced air the mass will sink and be 'heavier'.

When he says that humans would weigh less in a high pressure environment he is talking about human density specifically, which is not the densest material, exemplified by the fact that human bodies easily float in water.

If we consider a lead weight on a scale at the bottom of a swimming pool it is a fundamentally different scenario when compared with a human on a scale at the bottom of a swimming pool.
Title: Re: Increased gravity at the poles?
Post by: stack on November 12, 2018, 07:00:07 PM
If we consider a lead weight on a scale at the bottom of a swimming pool it is a fundamentally different scenario when compared with a human on a scale at the bottom of a swimming pool.

Is it fundamentally different or just that the two have different densities?
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 12, 2018, 07:01:10 PM
If we consider a lead weight on a scale at the bottom of a swimming pool it is a fundamentally different scenario when compared with a human on a scale at the bottom of a swimming pool.

Is it fundamentally different or just that the two have different densities?

Being pushed up is fundamentally different than being pushed down, yes.
Title: Re: Increased gravity at the poles?
Post by: edby on November 12, 2018, 07:06:50 PM
Once again. Suppose there is a 1 kg weight on the bathroom scales. I remove the weight, and while still carrying it, I now stand on the scales. By how much will the weighed amount increase?

So it is with the air. There is a big column of air on the bathroom scales. As soon as I step on the scales, I remove the direct effect of the air, but it remains because it is sitting on my head, as it were.

Buoyancy, as Tom rightly says, is something else. However, buoyancy would cause my weight on average to decrease at the poles, not increase, as Tom claims. I say 'on average' because the daily change in atmospheric pressure in London is far greater than the average difference between London and the poles.

My questions remain. (1) Do things weigh more at the poles and if so (2) why is that? 
Title: Re: Increased gravity at the poles?
Post by: edby on November 12, 2018, 07:21:05 PM
As it happens, the pressure in London (http://resource.npl.co.uk/pressure/pressure.html) is greater than at the South Pole (http://tgftp.nws.noaa.gov/weather/current/NZSP.html), at least today.
Title: Re: Increased gravity at the poles?
Post by: Bobby Shafto on November 12, 2018, 07:23:22 PM
It is not an "FE belief"
If you are saying (incorrectly) that barometric pressure is the "weight of air" to make a flat earth argument that greater air pressure increases weight, then that's a flat earth belief.

You are conflating earth-shape agnostic truths to arrive at an erroneous conclusion.
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 12, 2018, 07:24:59 PM
My questions remain. (1) Do things weigh more at the poles and if so (2) why is that?

I believe that your source answered it. If the mass of the object is equal to the air it displaced it is neither pushed upwards or downwards, if the mass of the object is less than the air it displaces, it is pushed upwards/lighter and if the mass of the object is more than the air it displaces it is pushed downwards/heavier.

Since the poles are generally of higher pressure, those effects will manifest greater there.
Title: Re: Increased gravity at the poles?
Post by: edby on November 12, 2018, 07:37:18 PM
My questions remain. (1) Do things weigh more at the poles and if so (2) why is that?

I believe that your source answered it. If the mass of the object is equal to the air it displaced it is neither pushed upwards or downwards, if the mass of the object is less than the air it displaces, it is pushed upwards/lighter and if the mass of the object is more than the air it displaces it is pushed downwards/heavier.

Since the poles are generally of higher pressure, those effects will manifest greater there.
So things will be (slightly) lighter at the poles, if it were only down to atmospheric pressure. But they are heavier. Why?
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 12, 2018, 07:50:56 PM
Quote
So things will be (slightly) lighter at the poles, if it were only down to atmospheric pressure. But they are heavier. Why?

It's only lighter at the poles if it's an object that is of low density, and lighter than the air it displaces. If the object is of high density, heavier than the air it displaces, the opposite effect will occur. If the object is at equal density to the air it displaces it will be neigher lighter or heavier.

From what I looked at the from the experiments, they are measuring metallic weights on scales.
Title: Re: Increased gravity at the poles?
Post by: markjo on November 12, 2018, 07:51:58 PM
"Note that if the mass of displaced air is equal to your mass, you will weigh nothing (neutral buoyancy), and if you weigh less than the displaced air (as you do in water) you will float."

And it follows form that if the mass weighs more than the displaced air the mass will sink and be 'heavier'.
Tom, in a nutshell, Archimedes Principle says:  "Every object is buoyed upwards by a force equal to the weight of the fluid the object displaces."  This means that dense objects will always become lighter as the density of the fluid displaced increases.

This link provides a pretty good explanation of buoyancy and points out a few things that may be confusing:
Quote from: https://www.khanacademy.org/science/physics/fluids/buoyant-force-and-archimedes-principle/a/buoyant-force-and-archimedes-principle-article
Surprisingly the buoyant force doesn't depend on the overall depth of the object submerged. In other words, as long as the can of beans is fully submerged, bringing it to a deeper and deeper depth will not change the buoyant force. This might seem strange since the pressure gets larger as you descend to deeper depths. But the key idea is that the pressures at the top and bottom of the can will both increase by the same amount and therefore cancel, leaving the total buoyant force the same.
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 12, 2018, 07:57:56 PM
Tom, in a nutshell, Archimedes Principle says:  "Every object is buoyed upwards by a force equal to the weight of the fluid the object displaces."  This means that dense objects will always become lighter as the density of the fluid displaced increases.

That is not what that quote means. It means that if the weight of the object is equal to the fluid it displaces it will pulled neither lower or higher.

But if the object is lighter than the fluid it displaces it will be pulled higher. Just the same, if the object is heavier than the fluid it displaces it will be pushed lower.
Title: Re: Increased gravity at the poles?
Post by: edby on November 12, 2018, 07:59:00 PM
This link provides a pretty good explanation of buoyancy and points out a few things that may be confusing:
True, but in his original reply to the OP, Tom claimed (1) that the atmosphere has weight, and atmospheric pressure "pushes down" on us and (2) The barometric pressure is higher at the poles, therefore (3) we will weigh more at the poles.

This argument is totally fallacious, as I pointed out above. It is true that the atmosphere has great weight, and pushes down on us, but it pushes down with the same weight on the bathroom scales even when I am not standing on them. When I do stand on them, I remove the weight from the scales themselves, but the weight remains pushing on my head. Net difference is my weight alone, atmospheric weight makes no difference.
Title: Re: Increased gravity at the poles?
Post by: edby on November 12, 2018, 08:00:39 PM
Tom, in a nutshell, Archimedes Principle says:  "Every object is buoyed upwards by a force equal to the weight of the fluid the object displaces."  This means that dense objects will always become lighter as the density of the fluid displaced increases.

That is not what that quote means. It means that if the weight of the object is equal to the fluid it displaces it will pulled neigher lower or higher.

But if the object is lighter than the fluid it displaces it will be pulled higher. Just the same, if the object is heavier than the fluid it displaces it will be pushed lower.
Very true, but in your original reply you claimed that the increase in our weight at the poles was due to the greater weight pushing down on our head. This is fallacious.

What is the true reason for the increased weight at the poles?
Title: Re: Increased gravity at the poles?
Post by: markjo on November 12, 2018, 08:21:52 PM
Tom, in a nutshell, Archimedes Principle says:  "Every object is buoyed upwards by a force equal to the weight of the fluid the object displaces."  This means that dense objects will always become lighter as the density of the fluid displaced increases.

That is not what that quote means. It means that if the weight of the object is equal to the fluid it displaces it will pulled neither lower or higher.

But if the object is lighter than the fluid it displaces it will be pulled higher. Just the same, if the object is heavier than the fluid it displaces it will be pushed lower.
Gravity always pushes the object down and buoyancy always pushes the object up.  Whether the object rises, floats or sinks depends on whether the buoyant force is greater than, equal to or less than the gravitational force.
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 12, 2018, 09:07:05 PM
Very true, but in your original reply you claimed that the increase in our weight at the poles was due to the greater weight pushing down on our head. This is fallacious.

What is the true reason for the increased weight at the poles?

Air, like water, does have weight to it. The thread just got nitpicky about buyancy.

Take a glass jar and fill it 1/4th of the way with sand.

Now fill the rest of the glass with water.

Are you to say that the sand does not feel the weight of the water upon it?

How is it possible to argue, as markjo does above, that this water is not pushing the sand down?
Title: Re: Increased gravity at the poles?
Post by: Bobby Shafto on November 12, 2018, 09:11:54 PM
Because downward force is not isolated from the upward buoyant force.

if the object is lighter than the fluid it displaces it will be pulled higher. Just the same, if the object is heavier than the fluid it displaces it will be pushed lower.

If the object doesn't change its volume, it's displacing the same amount of air regardless of pressure.

So, say location A has low pressure atmosphere and an object displaces X cubic whatevers of rarer, lower pressure air.

Location B has high pressure atmosphere and the object there displaces the same X cubic whatevers of denser air.

Which locations' displaced volume of air weighs more?

Location B, right?

At which location does the object with X volume experience a greater buoyant force?

Same answer. Location B.  Right?

Yes, higher pressure air "pushes down" more from above, but the buoyant force also "pushes up" more.

This is a key principle in scuba diving. Buoyancy compensators adjust the diver's volume to manage the amount of water being displaced as water density/pressure changes with depth. Great pressure with greater depth squeezes the diver and his neoprene, making him less voluminous and less buoyant. But adding air to the BCD increases volume and increases buoyancy by displacing more of the higher pressure water. If an object is non-compressible, its buoyancy will increase with increase in water pressure. The same is true of the atmosphere. High pressure air increases buoyancy, as long as volume remains constant.

The error is believing that fluid pressure is just a vector force in one direction. Bouyancy isn't "something else." It's part of the pressure force equation.
Title: Re: Increased gravity at the poles?
Post by: Dr Van Nostrand on November 12, 2018, 09:19:10 PM
Tom, in a nutshell, Archimedes Principle says:  "Every object is buoyed upwards by a force equal to the weight of the fluid the object displaces."  This means that dense objects will always become lighter as the density of the fluid displaced increases.

That is not what that quote means. It means that if the weight of the object is equal to the fluid it displaces it will pulled neigher lower or higher.

But if the object is lighter than the fluid it displaces it will be pulled higher. Just the same, if the object is heavier than the fluid it displaces it will be pushed lower.
Very true, but in your original reply you claimed that the increase in our weight at the poles was due to the greater weight pushing down on our head. This is fallacious.

What is the true reason for the increased weight at the poles?

Air, like water, does have weight to it. The thread just got nitpicky about buyancy.

Take a glass jar and fill it 1/4th of the way with sand.

Now fill the rest of the glass with water.

Are you to say that the sand does not feel the weight of the water upon it?

How is it possible to argue, as markjo does above, that this water is not pushing the sand down?


Ambient pressure is distributed in all directions. As someone pointed out upthread, it has no vector.

The weight of the water surrounds each sand grain from all directions.  It does not push 'down.'


The barometric pressure does not affect how much we weigh otherwise we'd see our weight fluctuate when the barometer changes.


However, we can be affected by the buoyancy of the atmosphere. We are less dense than air so we sink in air. We are comparable to the density of water so we float or sink based on how much fat (floats) or how much muscle (sinks) we have.  We are much less dense than liquid mercury so we float high is a body of mercury. However, the difference in buoyancy for a human in a low pressure atmosphere and a high pressure atmosphere is negligible.   
Title: Re: Increased gravity at the poles?
Post by: markjo on November 12, 2018, 09:31:53 PM
Very true, but in your original reply you claimed that the increase in our weight at the poles was due to the greater weight pushing down on our head. This is fallacious.

What is the true reason for the increased weight at the poles?

Air, like water, does have weight to it. The thread just got nitpicky about buyancy.

Take a glass jar and fill it 1/4th of the way with sand.

Now fill the rest of the glass with water.

Are you to say that the sand does not feel the weight of the water upon it?

How is it possible to argue, as markjo does above, that this water is not pushing the sand down?

Tom, the effect of buoyancy on dense objects is easy enough to test for yourself.
https://www.youtube.com/watch?v=ROXYr_SzNW4
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 12, 2018, 09:42:45 PM
Ambient pressure is distributed in all directions. As someone pointed out upthread, it has no vector.

The weight of the water surrounds each sand grain from all directions.  It does not push 'down.'

You are basically suggesting that if you were burried two feet under the sand of the deepest ocean that you would not be crushed, since as you argue, that sand is not feeling the downward weight of the ocean.

I think you are mistaken. My position is that you would be crushed.
Title: Re: Increased gravity at the poles?
Post by: Dr Van Nostrand on November 12, 2018, 09:45:52 PM
Ambient pressure is distributed in all directions. As someone pointed out upthread, it has no vector.

The weight of the water surrounds each sand grain from all directions.  It does not push 'down.'

You are basically suggesting that if you were burried two feet under the sand of the deepest ocean that you would not be crushed, since that sand is not feeling the weight of the ocean.

I think you are mistaken. My position is that you would be crushed.


You would be crushed by the ambient pressure crushing you in all directions. You would not be crushed flat.
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 12, 2018, 10:06:00 PM
You guys are a bit off.  Take a look at some back of the envelope calculations.  Forget water for now.  It's mostly considered to be non-compressible, but it slightly is.  Now consider AIR.  At an air pressure of 1018 hPa the density of air is about 1.2260 kg/cubic meter.  If you increase air pressure the density of air increases because air IS highly compressible.  Air at a pressure of 3000 hPa is 3.622 kg/cubic meter.  Now if you were to take a cubic meter block of balsa wood to the north pole and assumed it was in a vacuum it would weigh about 160 kg.  Now if you took that block of balsa wood out of the vacuum and put it in the air at 1018 hPa the effect of buoyancy would lighten the block by 1.226 kg.  Now the starting weight of the block would be about 158.774 kg.  If you INCREASE the air pressure to an unreasonable 3000 hPa then the same block would actually weigh less because the more dense area would 'float' a little more of the balsa block and it would then weigh 156.378 kg.  Of course the density of the air depends on the temperature and the dew point as well, but you get the point.  An increase in air pressure will actually cause something to weigh a little LESS because air compresses leading to a higher density and a little more buoyant effect.  As far as the argument that air doesn't have any mass, I better tell all the wind farm folks in the area that fact.  They seem to think that the horizontal flow of air decelerating against the fan blades produces a force that can be turned into electrical power.  Newton was kind enough to give us the equation F=MA.  Of course that also means that water has mass as well, otherwise a ship's propeller just wouldn't work either.  Shall we argue that the whole earth must have mass? 
Title: Re: Increased gravity at the poles?
Post by: Baby Thork on November 13, 2018, 12:23:19 AM
This thread is a bloodbath of scientific illiteracy.

Watch the video below. You should understand the difference between something in water and something on water.

If something is in water it displaces its volume of water.
If something is on water, it displaces its weight in water.

A scuba diver is in water. The atmosphere is on water. They are not analogous.

https://www.youtube.com/watch?v=E1W72yddW64

Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 13, 2018, 01:20:17 AM
Very true, but in your original reply you claimed that the increase in our weight at the poles was due to the greater weight pushing down on our head. This is fallacious.

What is the true reason for the increased weight at the poles?

Air, like water, does have weight to it. The thread just got nitpicky about buyancy.

Take a glass jar and fill it 1/4th of the way with sand.

Now fill the rest of the glass with water.

Are you to say that the sand does not feel the weight of the water upon it?

How is it possible to argue, as markjo does above, that this water is not pushing the sand down?

Tom, the effect of buoyancy on dense objects is easy enough to test for yourself.
https://www.youtube.com/watch?v=ROXYr_SzNW4 (https://www.youtube.com/watch?v=ROXYr_SzNW4)

Marjo, it depends how you weigh it. If you have a jar of sand on a scale and add water to the jar, it will weigh more than just the jar and sand alone. The sand now has more weight on top of it.

This link provides a pretty good explanation of buoyancy and points out a few things that may be confusing:
True, but in his original reply to the OP, Tom claimed (1) that the atmosphere has weight, and atmospheric pressure "pushes down" on us and (2) The barometric pressure is higher at the poles, therefore (3) we will weigh more at the poles.

This argument is totally fallacious, as I pointed out above. It is true that the atmosphere has great weight, and pushes down on us, but it pushes down with the same weight on the bathroom scales even when I am not standing on them. When I do stand on them, I remove the weight from the scales themselves, but the weight remains pushing on my head. Net difference is my weight alone, atmospheric weight makes no difference.

Detecting the difference in atmospheric weight depends on the type of scale and calibration.

If you take an old fashioned bathroom scale and drill holes through the exterior and put it on the bottom of a swimming pool so that it's interior is filled, then it will read zero. If you wrap the scale it in seran wrap and put it on the bottom of the pool then it is feeling the tremendous weight of the water above it.

Subjectively, the water is much heavier than the air, but it is possible to calibrate the difference to zero. Depending on the type of scale and the procedure, the difference may be felt.
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 13, 2018, 03:59:08 AM
For many years there have been many different entities that have been surveying and mapping the gravity field of the earth.  There has been established a reference gravity field called the 'Geodetic Reference System' and that reference is being constantly updated with corrections as conditions change on the earth.  Gravity is a force and is a vector quantity.  Things inside the earth and on top of the earths surface can change the gravity force vector.  You can be sure that with all the volcanic activity in Hawaii a short time ago there has been changes to the local gravitational field in that area as a bunch of lava flowed out of the earth onto the earth's surface.  The Geodetic Survey folks call the earth an ellipsoid and have detailed equations that show the nominal variation of the gravity vector at different latitudes.  You would expect that as the distance to the earth's center is a bit further at the equator than at the poles.  It is interesting to note that as part of the measurement system a correction is made for the buoyancy due to air.  The answer to the original question on this thread is yes, you can expect a difference in weight the further North you go.  The survey folks have well calibrated instruments that are used on land, at sea and in the air to map the gravity field of the earth.  Unfortunately, since 'gravity' on the earth isn't an "FE belief" I don't know what else to say.  There are countless scientists and engineers working for universities and governments, worldwide, that study, survey, and chart the gravity of the earth.  Are they all just wasting time & money?
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 13, 2018, 04:41:44 AM
As a follow up to my last post, look at this:

http://physicstasks.eu/930/spring-scale-on-the-pole-and-on-the-equator

Quote
We calibrated a spring scale on the North Pole and then we moved the scale to the Equator.

Does the spring scale give the same readings as on the pole?

The experiment is about taking a spring scale that is calibrated at the North Pole and moving it to the Equator.

This is a different experiment than weighing a mass in two different areas with scales that have been calibrated for their local areas.
Title: Re: Increased gravity at the poles?
Post by: edby on November 13, 2018, 08:42:21 AM
As a follow up to my last post, look at this:

http://physicstasks.eu/930/spring-scale-on-the-pole-and-on-the-equator

Quote
We calibrated a spring scale on the North Pole and then we moved the scale to the Equator.

Does the spring scale give the same readings as on the pole?

The experiment is about taking a spring scale that is calibrated at the North Pole and moving it to the Equator.

This is a different experiment than weighing a mass in two different areas with scales that have been calibrated for their local areas.
The conclusion is that the difference in weight is nothing to do with atmospheric pressure, but rather of difference in centrifugal force. This answers my question.
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 13, 2018, 01:11:10 PM
As a follow up to my last post, look at this:

http://physicstasks.eu/930/spring-scale-on-the-pole-and-on-the-equator

Quote
We calibrated a spring scale on the North Pole and then we moved the scale to the Equator.

Does the spring scale give the same readings as on the pole?

The experiment is about taking a spring scale that is calibrated at the North Pole and moving it to the Equator.

This is a different experiment than weighing a mass in two different areas with scales that have been calibrated for their local areas.
The conclusion is that the difference in weight is nothing to do with atmospheric pressure, but rather of difference in centrifugal force. This answers my question.

If this were the case, why do they specifically not calibrate the scale again at the equator or use a different scale that is calibrated? If the weight were truly heavier in one location, this difference should appear on calibrated scales.

The experiment is specifically about taking a scale calibrated for the North Pole to the Equator, and so the idea that this must be measuring weight difference of the mass and nothing more is fallacious.

Where are the controls in this experiment to show what is and is not being measured? Since you are presenting this as fact, you should be expected to defend these experiments.
Title: Re: Increased gravity at the poles?
Post by: AllAroundTheWorld on November 13, 2018, 01:33:46 PM
This is confusing. Are you now claiming that weight doesn’t vary between the pole and equator?
You’ve spent the last page saying that it does because of air pressure difference.
Wrongly of course, but are you now saying it doesn’t?
Far as I understand the weight variation is more to do with the earth’s rotation, not because of earth’s oblateness
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 13, 2018, 01:38:48 PM
This is confusing. Are you now claiming that weight doesn’t vary between the pole and equator?
You’ve spent the last page saying that it does because of air pressure difference.
Wrongly of course, but are you now saying it doesn’t?
Far as I understand the weight variation is more to do with the earth’s rotation, not because of earth’s oblateness

Different areas have different air pressures and therefore different weights to their atmosphere. They took a scale calibrated for an area of higher pressure to an area of lower pressure and are measuring the difference seen on that scale.
Title: Re: Increased gravity at the poles?
Post by: edby on November 13, 2018, 01:38:58 PM
This is confusing. Are you now claiming that weight doesn’t vary between the pole and equator?
You’ve spent the last page saying that it does because of air pressure difference.
Wrongly of course, but are you now saying it doesn’t?
Far as I understand the weight variation is more to do with the earth’s rotation, not because of earth’s oblateness

Different areas have different air pressures and therefore different weights to their atmosphere. They took a scale calibrated for an area of higher pressure to an area of lower pressure and are measuring the difference seen on that scale.

Quote
https://en.wikipedia.org/wiki/Gravimetry
An instrument used to measure gravity is known as a gravimeter, or gravinometer. For a small body, general relativity predicts gravitational effects indistinguishable from the effects of acceleration by the equivalence principle. Thus, gravimeters can be regarded as special-purpose accelerometers. Many weighing scales may be regarded as simple gravimeters. In one common form, a spring is used to counteract the force of gravity pulling on an object. The change in length of the spring may be calibrated to the force required to balance the gravitational pull. The resulting measurement may be made in units of force (such as the newton), but is more commonly made in units of gals.

Researchers use more sophisticated gravimeters when precise measurements are needed. When measuring the Earth's gravitational field, measurements are made to the precision of microgals to find density variations in the rocks making up the Earth. Several types of gravimeters exist for making these measurements, including some that are essentially refined versions of the spring scale described above. These measurements are used to define gravity anomalies.

Besides precision, stability is also an important property of a gravimeter, as it allows the monitoring of gravity changes. These changes can be the result of mass displacements inside the Earth, or of vertical movements of the Earth's crust on which measurements are being made: remember that gravity decreases 0.3 mGal for every metre of height. The study of gravity changes belongs to geodynamics.

The majority of modern gravimeters use specially-designed metal or quartz zero-length springs to support the test mass. Zero-length springs do not follow Hooke's Law, instead they have a force proportional to their length. The special property of these springs is that the natural resonant period of oscillation of the spring-mass system can be made very long - approaching a thousand seconds. This detunes the test mass from most local vibration and mechanical noise, increasing the sensitivity and utility of the gravimeter. Quartz and metal springs are chosen for different reasons; quartz springs are less affected by magnetic and electric fields while metal springs have a much lower drift (elongation) with time. The test mass is sealed in an air-tight container so that tiny changes of barometric pressure from blowing wind and other weather do not change the buoyancy of the test mass in air.

Spring gravimeters are, in practice, relative instruments which measure the difference in gravity between different locations. A relative instrument also requires calibration by comparing instrument readings taken at locations with known complete or absolute values of gravity. Absolute gravimeters provide such measurements by determining the gravitational acceleration of a test mass in vacuum. A test mass is allowed to fall freely inside a vacuum chamber and its position is measured with a laser interferometer and timed with an atomic clock. The laser wavelength is known to ±0.025 ppb and the clock is stable to ±0.03 ppb as well. Great care must be taken to minimize the effects of perturbing forces such as residual air resistance (even in vacuum), vibration, and magnetic forces. Such instruments are capable of an accuracy of about two parts per billion or 0.002 mGal[1] and reference their measurement to atomic standards of length and time. Their primary use is for calibrating relative instruments, monitoring crustal deformation, and in geophysical studies requiring high accuracy and stability. However, absolute instruments are somewhat larger and significantly more expensive than relative spring gravimeters, and are thus relatively rare.
Title: Re: Increased gravity at the poles?
Post by: Curious Squirrel on November 13, 2018, 01:41:03 PM
This is confusing. Are you now claiming that weight doesn’t vary between the pole and equator?
You’ve spent the last page saying that it does because of air pressure difference.
Wrongly of course, but are you now saying it doesn’t?
Far as I understand the weight variation is more to do with the earth’s rotation, not because of earth’s oblateness

Different areas have different air pressures and therefore different weights to their atmosphere. They took a scale calibrated for an area of higher pressure to an area of lower pressure and are measuring the difference seen on that scale.
Can you show evidence the North Pole is an area of higher pressure? This air pressure map (at least during July) suggest this is not necessarily the case.

https://www.mapsofworld.com/world-maps/image/wether/wind-and-pressure-july-enlarge.jpg
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 13, 2018, 01:42:32 PM
Edby, the experiment says nothing about using a device with a vaccum chamber in it, or dropping the object in a vaccum chamber. It says and depicts in the article that the device is a regular spring scale.

(http://physicstasks.eu/media/00930/spring_scale.page.tagged.jpg)\

Can you show evidence the North Pole is an area of higher pressure? This air pressure map (at least during July) suggest this is not necessarily the case.

https://www.mapsofworld.com/world-maps/image/wether/wind-and-pressure-july-enlarge.jpg

Look up the Polar High.
Title: Re: Increased gravity at the poles?
Post by: edby on November 13, 2018, 01:46:47 PM
Note particularly the bit in bold.
Quote
The majority of modern gravimeters use specially-designed metal or quartz zero-length springs to support the test mass. Zero-length springs do not follow Hooke's Law, instead they have a force proportional to their length. The special property of these springs is that the natural resonant period of oscillation of the spring-mass system can be made very long - approaching a thousand seconds. This detunes the test mass from most local vibration and mechanical noise, increasing the sensitivity and utility of the gravimeter. Quartz and metal springs are chosen for different reasons; quartz springs are less affected by magnetic and electric fields while metal springs have a much lower drift (elongation) with time. The test mass is sealed in an air-tight container so that tiny changes of barometric pressure from blowing wind and other weather do not change the buoyancy of the test mass in air.
Title: Re: Increased gravity at the poles?
Post by: Bobby Shafto on November 13, 2018, 01:48:04 PM
Different areas have different air pressures and therefore different weights to their atmosphere. They took a scale calibrated for an area of higher pressure to an area of lower pressure and are measuring the difference seen on that scale.
I don't understand. That's what I would do. Or, calibrate it at the equator and take it to the north pole. Or calibrate it in Helsinki and take it to the equator and north pole.

If you recalibrate, between each location, you're nullifying the very point of the experiment.

Aren't you? Or am I completely lost here?
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 13, 2018, 01:48:36 PM
Note particularly the bit in bold.
Quote
The majority of modern gravimeters use specially-designed metal or quartz zero-length springs to support the test mass. Zero-length springs do not follow Hooke's Law, instead they have a force proportional to their length. The special property of these springs is that the natural resonant period of oscillation of the spring-mass system can be made very long - approaching a thousand seconds. This detunes the test mass from most local vibration and mechanical noise, increasing the sensitivity and utility of the gravimeter. Quartz and metal springs are chosen for different reasons; quartz springs are less affected by magnetic and electric fields while metal springs have a much lower drift (elongation) with time. The test mass is sealed in an air-tight container so that tiny changes of barometric pressure from blowing wind and other weather do not change the buoyancy of the test mass in air.

That wiki quote is not the procedure that is described in the link. It is depicting measuring the weight in an open environment with a regular spring scale.
Title: Re: Increased gravity at the poles?
Post by: edby on November 13, 2018, 01:50:44 PM
Different areas have different air pressures and therefore different weights to their atmosphere. They took a scale calibrated for an area of higher pressure to an area of lower pressure and are measuring the difference seen on that scale.
I don't understand. That's what I would do. Or, calibrate it at the equator and take it to the north pole. Or calibrate it in Helsinki and take it to the equator and north pole.

If you recalibrate, between each location, you're nullifying the very point of the experiment.

Aren't you? Or am I completely lost here?
I think Tom is still under the impression that the changes in the 'weight of air' cause a change in the measured weight.
Title: Re: Increased gravity at the poles?
Post by: Curious Squirrel on November 13, 2018, 01:55:23 PM
Can you show evidence the North Pole is an area of higher pressure? This air pressure map (at least during July) suggest this is not necessarily the case.

https://www.mapsofworld.com/world-maps/image/wether/wind-and-pressure-july-enlarge.jpg

Look up the Polar High.
Average mean sea level pressure over the last 15 years both during the months of June, July, and August (top) and December, January, and February (bottom)

(https://upload.wikimedia.org/wikipedia/commons/1/17/Mslp-jja-djf.png)

The Polar Highs occur *above* sea level. Usually on the order of km above sea level. They would not have an affect on an experiment performed on the ground.
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 13, 2018, 02:06:42 PM
That is incorrect:

https://www.pmfias.com/pressure-belts-pressure-systems-equatorial-low-sub-tropical-high-sub-polar-low-polar-high/

Quote
World Distribution of Sea Level Pressure

The atmosphere exerts a pressure of 1034 gm per square cm at sea level. This amount of pressure is exerted by the atmosphere at sea level on all animals, plants, rocks, etc.

Near the equator the sea level pressure is low and the area is known as equatorial low. Along 30° N and 30° S are found the high-pressure areas known as the subtropical highs. Further pole wards along 60° N and 60° S, the low-pressure belts are termed as the sub polar lows. Near the poles the pressure is high and it is known as the polar high.

and further down:

Quote
Polar High Pressure Belt

- The polar highs are small in area and extend around the poles.
- They lie around poles between 80 – 90° N and S latitudes.

Formation

- The air from sub-polar low pressure belts after saturation becomes dry. This dry air becomes cold while moving towards poles through upper troposphere.
- The cold air (heavy) on reaching poles subsides creating a high pressure belt at the surface of earth.
Title: Re: Increased gravity at the poles?
Post by: Bobby Shafto on November 13, 2018, 02:08:05 PM
Different areas have different air pressures and therefore different weights to their atmosphere. They took a scale calibrated for an area of higher pressure to an area of lower pressure and are measuring the difference seen on that scale.
I don't understand. That's what I would do. Or, calibrate it at the equator and take it to the north pole. Or calibrate it in Helsinki and take it to the equator and north pole.

If you recalibrate, between each location, you're nullifying the very point of the experiment.

Aren't you? Or am I completely lost here?
I think Tom is still under the impression that the changes in the 'weight of air' cause a change in the measured weight.
I know, but if you recalibrate between measurements, how do you know? The point is to measure the change due to location. If you recalibrate at the new location, what are you recalibrating to? You're negating being able to measure what you suspect might cause measurement to change.
Title: Re: Increased gravity at the poles?
Post by: Curious Squirrel on November 13, 2018, 02:11:38 PM
At present there is only a 10 hPa difference between the North Pole, and a low point on the equator. These 'Polar Highs' at any rate do not appear to create a very large difference. Could anyone do the math on the difference in pressure between 1015 hPa and 1005 hPa? Would it be enough to produce what is noted in the experiment link?

https://earth.nullschool.net/#current/wind/surface/level/overlay=mean_sea_level_pressure/winkel3/loc=-7.931,88.751
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 13, 2018, 02:23:44 PM
Of course the OP was about the subject of Clairaut's Theorem.  The idea was that you could show that the earth had a bit shorter distance to the center at the poles than at the equator.  The arguments about the air pressures and water pressures pretty much just cloud the main argument (which is a standard tactic).  At one time you might have needed to know the air pressure to use as a correction factor (because of buoyancy) but all that is irrelevant now.  You have a different weight at different latitudes and because of local anomalies due to the fact that the earth is not perfectly spherical or homogeneous throughout.  A large number of people from many countries  spend countless hours surveying and mapping these gravitational fields just like they do with a standard topographical map of the earths surface.  Of course FE doesn't do gravity or spherical so the whole argument is moot here anyway.   
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 13, 2018, 02:24:27 PM
At present there is only a 10 hPa difference between the North Pole, and a low point on the equator. These 'Polar Highs' at any rate do not appear to create a very large difference. Could anyone do the math on the difference in pressure between 1015 hPa and 1005 hPa? Would it be enough to produce what is noted in the experiment link?

https://earth.nullschool.net/#current/wind/surface/level/overlay=mean_sea_level_pressure/winkel3/loc=-7.931,88.751

Those weather map air pressure estimates are not based on direct measurement of the atmosphere. They do not have barometers spaced out every mile. Those numbers are loose model transformations, based on cloud, precipitation, and weather movement, as estimated by weather radar.
Title: Re: Increased gravity at the poles?
Post by: markjo on November 13, 2018, 02:26:56 PM
As a follow up to my last post, look at this:

http://physicstasks.eu/930/spring-scale-on-the-pole-and-on-the-equator

Quote
We calibrated a spring scale on the North Pole and then we moved the scale to the Equator.

Does the spring scale give the same readings as on the pole?

The experiment is about taking a spring scale that is calibrated at the North Pole and moving it to the Equator.

This is a different experiment than weighing a mass in two different areas with scales that have been calibrated for their local areas.
The conclusion is that the difference in weight is nothing to do with atmospheric pressure, but rather of difference in centrifugal force. This answers my question.

If this were the case, why do they specifically not calibrate the scale again at the equator or use a different scale that is calibrated? If the weight were truly heavier in one location, this difference should appear on calibrated scales.

The experiment is specifically about taking a scale calibrated for the North Pole to the Equator, and so the idea that this must be measuring weight difference of the mass and nothing more is fallacious.

Where are the controls in this experiment to show what is and is not being measured? Since you are presenting this as fact, you should be expected to defend these experiments.
Tom, the the scale being calibrated at the north pole and reference mass being measured are the controls in the experiment.  Changes in the weight of the reference mass at different locations is what is being measured.   

Another example of this type of experiment is the Kern Gnome experiment where a precision scale is calibrated in one location and then is used to weigh a ceramic garden gnome at various locations around the world.  The results were consistent with previously mapped gravitational variations.
https://www.campaignlive.co.uk/article/kern-gnome-experiment/1191121
http://gnome-experiment.com/
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 13, 2018, 02:39:46 PM
Tom, the the scale being calibrated at the north pole and reference mass being measured are the controls in the experiment.  Changes in the weight of the reference mass at different locations is what is being measured.   

Another example of this type of experiment is the Kern Gnome experiment where a precision scale is calibrated in one location and then a ceramic garden gnome is weighed at various locations around the world.  The results were consistent with previously mapped gravitational variations.
https://www.campaignlive.co.uk/article/kern-gnome-experiment/1191121
http://gnome-experiment.com/

These are not controlled experiments. If the gnome device is being calibrated at the tropics, and then taken to the antarctic where the pressure is higher, and the atmosphere is heavier, we should expect a different result there.
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 13, 2018, 02:54:27 PM
I love the Gnome experiment.  If anything, the colder, high pressure, more dense air would actually make the Gnome weigh very slightly less.  That would actually be in favor of FE.  Please consult a text book on fluid mechanics to see just why this would be true. 
Title: Re: Increased gravity at the poles?
Post by: Bobby Shafto on November 13, 2018, 02:55:24 PM
Tom, the the scale being calibrated at the north pole and reference mass being measured are the controls in the experiment.  Changes in the weight of the reference mass at different locations is what is being measured.   

Another example of this type of experiment is the Kern Gnome experiment where a precision scale is calibrated in one location and then a ceramic garden gnome is weighed at various locations around the world.  The results were consistent with previously mapped gravitational variations.
https://www.campaignlive.co.uk/article/kern-gnome-experiment/1191121
http://gnome-experiment.com/

These are not controlled experiments. If the gnome device is being calibrated at the tropics, and then taken to the antarctic where the pressure is higher, and the atmosphere is heavier, we should expect a different result there.
The way you composed that makes it sound as if results being different from what you expect means the experiment wasn’t controlled.
Title: Re: Increased gravity at the poles?
Post by: edby on November 13, 2018, 03:02:04 PM
Tom, the spring device will have a platform on which to place the object measured. The platform will have a top and a bottom surface. If the air flows freely, the force acting upwards on the bottom will be exactly equal to the force acting downwards at the top. Increase in atmospheric pressure will affect both equally, and will cancel out. If of course the air does not flow freely, and the pressure at the bottom is different from the top, this will affect the apparent weight. This will not normally happen.
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 13, 2018, 03:22:03 PM
Take a look at the Kern Precision Scales website.  They show the Gnome and the precision scale in a nice case.  These folks make scales for a living and you can be sure that the experiment left very little to chance.  They ship scales from scientist to scientist worldwide.  The whole idea was to show the differences of gravity due to the location on the earth.  My quick, back of the envelope, calculations of the differences of weight due to changes in atmospheric pressures and temperatures at the various places in the world would be very, very small.  Forget everything about the weather corrections.  Think the differences in weight (mass) due to the variations in the gravity on the earth.  Clairaut is probably rolling over in glee as the results come in.
Title: Re: Increased gravity at the poles?
Post by: edby on November 13, 2018, 06:33:06 PM
Think the differences in weight (mass) due to the variations in the gravity on the earth. 
I think you will find the mass doesn't change, although the weight does.
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 13, 2018, 06:53:54 PM
You are indeed 100% correct.  An object's mass (it's resistance to acceleration) wouldn't change (my bad).  It's weight, the force of attraction between 2 masses would change in this case.  If you believe in the universal law of gravitation you would expect an object of any mass to weigh a bit more at the earth's poles because they are just a bit closer to the center of the earth's mass.  That was the whole idea of the original Clairaut experiment to show that the earth's shape wasn't quite a perfect sphere.  Modern day equipment has been used to verify that theory countless times.   
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 13, 2018, 07:11:42 PM
Tom, the spring device will have a platform on which to place the object measured. The platform will have a top and a bottom surface. If the air flows freely, the force acting upwards on the bottom will be exactly equal to the force acting downwards at the top. Increase in atmospheric pressure will affect both equally, and will cancel out. If of course the air does not flow freely, and the pressure at the bottom is different from the top, this will affect the apparent weight. This will not normally happen.

Neither the spring scale experiment or the gnome experiment are described as using a box enclosure or a vacuum sealed enclosure.
Title: Re: Increased gravity at the poles?
Post by: edby on November 13, 2018, 07:57:37 PM
Tom, the spring device will have a platform on which to place the object measured. The platform will have a top and a bottom surface. If the air flows freely, the force acting upwards on the bottom will be exactly equal to the force acting downwards at the top. Increase in atmospheric pressure will affect both equally, and will cancel out. If of course the air does not flow freely, and the pressure at the bottom is different from the top, this will affect the apparent weight. This will not normally happen.

Neither the spring scale experiment or the gnome experiment are described as using a box enclosure or a vacuum sealed enclosure.
Both will have a platform to support the weighed object, and the platform will have a top and bottom. The upward force on the bottom equals downward force on top.
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 13, 2018, 09:20:57 PM
Tom, the spring device will have a platform on which to place the object measured. The platform will have a top and a bottom surface. If the air flows freely, the force acting upwards on the bottom will be exactly equal to the force acting downwards at the top. Increase in atmospheric pressure will affect both equally, and will cancel out. If of course the air does not flow freely, and the pressure at the bottom is different from the top, this will affect the apparent weight. This will not normally happen.

Neither the spring scale experiment or the gnome experiment are described as using a box enclosure or a vacuum sealed enclosure.
Both will have a platform to support the weighed object, and the platform will have a top and bottom. The upward force on the bottom equals downward force on top.

Do you see a box or container on these scales?

(https://physicstasks.eu/media/00930/spring_scale.page.tagged.jpg)

(https://img.purch.com/w/660/aHR0cDovL3d3dy5saXZlc2NpZW5jZS5jb20vaW1hZ2VzL2kvMDAwLzAyNS82MTcvb3JpZ2luYWwva2Vybi1nb2xkZW4tZ2F0ZS0xMjAzMjEuanBn)
Title: Re: Increased gravity at the poles?
Post by: edby on November 13, 2018, 09:29:21 PM
Do you see a box or container on these scales?
I used the term 'platform'.
Title: Re: Increased gravity at the poles?
Post by: markjo on November 13, 2018, 09:30:28 PM
Tom, the spring device will have a platform on which to place the object measured. The platform will have a top and a bottom surface. If the air flows freely, the force acting upwards on the bottom will be exactly equal to the force acting downwards at the top. Increase in atmospheric pressure will affect both equally, and will cancel out. If of course the air does not flow freely, and the pressure at the bottom is different from the top, this will affect the apparent weight. This will not normally happen.

Neither the spring scale experiment or the gnome experiment are described as using a box enclosure or a vacuum sealed enclosure.
High precision gravimeters are designed to be much more accurate than spring scales or the gnome experiment.  The spring scale and gnome experiments can act as poor man's gravimeters that can detect gravitational variations, just not as accurately as a dedicated gravimeter.  Gravitational variations are why scales must be calibrated locally using known reference masses. 

To borrow an argument from Thork, if air pressure was a factor in an object's weight, then you could get rich by buying precious metals on a cold stormy day when air pressure is low and selling on a bright sunny day when the air pressure is higher.
Title: Re: Increased gravity at the poles?
Post by: edby on November 13, 2018, 09:48:20 PM
This would make a good Flat Earth experiment. I have a barometer with me (currently reading 1036mb), and I can buy a digital weighing machine. Place 1 kg weight on the machine and plot the weight against different daily pressures. Any predictions on the result?
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 13, 2018, 10:23:02 PM
Yea, my predictions would be a variation in the micro-grams category, assuming you used a kg of gold as your weight.  Where did you say you lived?
Title: Re: Increased gravity at the poles?
Post by: edby on November 13, 2018, 10:25:11 PM
This is also a very strong test for the UA hypothesis. If the surface of the earth is a rigid plane and accelerating upwards at 9.8 m/s^2, it must be accelerating at the same rate at every point in the surface (otherwise it would deform). But this is inconsistent with the difference in weight that we seem to observe.

Yea, my predictions would be a variation in the micro-grams category, assuming you used a kg of gold as your weight.  Where did you say you lived?
I think the lead weight from the old clock will do just as well (unless you can lend me the gold).
Title: Re: Increased gravity at the poles?
Post by: Bobby Shafto on November 13, 2018, 10:26:46 PM
Yea, my predictions would be a variation in the micro-grams category, assuming you used a kg of gold as your weight.  Where did you say you lived?
My prediction would be any variation would not correlate with changes in air pressure.
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 13, 2018, 10:35:27 PM
Maybe I can lend you some kryptonite.
The problems with a flat earth are even worse that that.  If you have UA, then you also have to find a way of accelerating the sun and moon as well.  They also need to be rotating which will require another energy source to keep everything moving in a circle (or maybe a pole with a cable).  That is, unless you want to forget Newton altogether.     
Title: Re: Increased gravity at the poles?
Post by: edby on November 14, 2018, 09:50:17 AM
FYI this (http://resource.npl.co.uk/pressure/pressure.html) shows the pressure variation close to London. Currently around 1020. By contrast, the history of pressure at McMurdo (https://www.weatheronline.co.uk/weather/maps/city?LANG=en&SI=mph&CEL=C&WMO=89664&TIME=std&CONT=aris&R=0&LEVEL=140&REGION=0022&LAND=AC&ART=luftdruck&NOREGION=1&PLZ=&PLZN=&SORT=__&TEMP=___&WETTER=__&&TYP=__&SEITE=0) shows a current range between 970 and 980, so pressure at the moment is much lower at high southerly latitudes.

Note also the range in London for the past two years is 980-1040, or about 6%. If Tom’s theory is correct, this should correspond to a 6% variation in weight. However we do not observe this in the gnome experiment, where the variation is more like 0.5%, close to Clairaut’s prediction.
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 14, 2018, 03:28:13 PM
I did some quick calculations.  I SWAGed it (Scientific Wild Ass Guess) and said that the volume of the Gnome was about 61.6 cm cubed.  I could have had Archeimedes give it a bath, but he isn't around anymore.  That means that the difference in weight due to the buoyancy of air at different densities due to change in atmospheric pressure would be about 4 millionths of a gram.  You wouldn't be able to see it on the Kern scale as good as it is.  Now the weight difference due to the measured difference in gravity at the poles and at the equator is a different story.  You can also apply the Somigliana equation to compensate for the effect of centrifugal force at different latitudes and you still come out with around a half percent difference in weight between the poles and the equator.  That's close to the measured difference in the weight observed in the traveling Gnome.  I suppose you could try to say that the flat earth is tumbling, but that doesn't even work.  As much as I hate to do it I'll give Tom a huge box of ammunition with the link: https://en.wikipedia.org/wiki/Spherical_cow.  I just thought that it applies to this situation.   
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 14, 2018, 05:59:23 PM
https://www.arlynscales.com/scale-knowledge/factors-can-affect-scales-accuracy/

Quote
Factors That Can Affect Your Scale’s Accuracy

...

Differences in air pressure – Scales can provide inaccurate measurements if the air pressure from the calibration environment is different than the operating environment.

Shocking. Both the spring scale experiment and the gnome experiment scales were calibrated for one environment and taken to another.
Title: Re: Increased gravity at the poles?
Post by: edby on November 14, 2018, 06:55:29 PM
https://www.arlynscales.com/scale-knowledge/factors-can-affect-scales-accuracy/

Quote
Factors That Can Affect Your Scale’s Accuracy

...

Differences in air pressure – Scales can provide inaccurate measurements if the air pressure from the calibration environment is different than the operating environment.

Shocking. Both the spring scale experiment and the gnome experiment scales were calibrated for one environment and taken to another.
Causing an error of 4 micrograms, according to Ron above.
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 14, 2018, 07:01:15 PM
The link you gave was for Arlyn Scales.  Of course, the Gnome was measured with a Kern scale.  The superior Kern scales can be compensated for your local conditions either at the factory before your item is shipped, or you can do it yourself.  All of that is irrelevant in this case anyway.  You are confusing the idea of mass and weight.  A mass standard is universal, at least on the planet earth, and is the resistance of that mass to being accelerated by a force.  There is an international standard for mass here on the earth.  Weight on the other hand is a measurement of the gravitational force on a given mass by the mass of the earth (usually).  The Kern scales can be compensated for your individual location before it’s shipped.  The whole idea of the Gnome exercise would be to explain that the earth’s gravitational force is different in different locations and is the reason that Kern should be paid extra to compensate your precision scale to your exact location.  Mass is much more difficult to measure than is weight.  If you have a compensated scale, then your weight and mass should be the same anywhere you measure it.  Shocking.
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 14, 2018, 07:12:07 PM
Causing an error of 4 micrograms, according to Ron above.

And according to you there can be a 6% difference:

Quote from: edby
Note also the range in London for the past two years is 980-1040, or about 6%. If Tom’s theory is correct, this should correspond to a 6% variation in weight.

Which expert opinion should we believe?
Title: Re: Increased gravity at the poles?
Post by: edby on November 14, 2018, 07:13:52 PM
Causing an error of 4 micrograms, according to Ron above.

And according to you there can be a 6% difference:

Quote from: edby
Note also the range in London for the past two years is 980-1040, or about 6%. If Tom’s theory is correct, this should correspond to a 6% variation in weight.

Which expert opinion should we believe?

We should not believe experts. We should do the test ourselves. According to you, the 6% variation in pressure should lead to a 6% variation in weight. Is that your hypothesis? Yes or no?

(If you state the hypothesis clearly, I will buy some precision scales and calibrate them, then test against observed atmospheric pressure).
Title: Re: Increased gravity at the poles?
Post by: edby on November 14, 2018, 07:17:15 PM
And according to you there can be a 6% difference:
Quote from: edby
Note also the range in London for the past two years is 980-1040, or about 6%. If Tom’s theory is correct, this should correspond to a 6% variation in weight.
Also, where did I say that there was a 6% difference in WEIGHT?? The '980-1040' range refers to atmospheric pressure, not the object weighed.
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 14, 2018, 07:21:00 PM
There is some confusion here.  The 4 micrograms difference was just my estimation of the compensation needed due to the changes of atmospheric pressures.  The 6% variation in weights were due to the differences in the gravitational attraction of the standardized mass of the Gnome.  Probably 6% is a bit too high, it's probably closer to 5%, but it's still significant and still implies that the earth is not under a worldwide constant acceleration of 9.81 meters per second squared.  It also implies that the earth is not perfectly spherical and was the whole idea behind the experiment in the first place. 
Title: Re: Increased gravity at the poles?
Post by: edby on November 14, 2018, 07:25:50 PM
There is some confusion here.  The 4 micrograms difference was just my estimation of the compensation needed due to the changes of atmospheric pressures.  The 6% variation in weights were due to the differences in the gravitational attraction of the standardized mass of the Gnome.  Probably 6% is a bit too high, it's probably closer to 5%, but it's still significant and still implies that the earth is not under a worldwide constant acceleration of 9.81 meters per second squared.  It also implies that the earth is not perfectly spherical and was the whole idea behind the experiment in the first place.
Actually the 6% I was referring to was the 980-1040mb seasonal variation in pressure in London, which Tom confused with variation in weight, so there is a lot of confusion here, as usual.
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 14, 2018, 07:32:35 PM
Besides that, if the earth were under a constant acceleration (UA) Kern wouldn't have to compensate their equipment for different locations.  I'm thinking that this isn't another government conspiracy.  I think the bigger worry would be that when I buy the next batch of unobtainium at the hardware store I'll have to watch that the salesman doesn't have his thumb on the scale.
Title: Re: Increased gravity at the poles?
Post by: edby on November 14, 2018, 07:37:19 PM
Besides that, if the earth were under a constant acceleration (UA) Kern wouldn't have to compensate their equipment for different locations.  I'm thinking that this isn't another government conspiracy.  I think the bigger worry would be that when I buy the next batch of unobtainium at the hardware store I'll have to watch that the salesman doesn't have his thumb on the scale.
Right, but Tom thinks the compensation is necessary because of the difference in atmospheric pressure between different locations. Presumably we even need to compensate for the same location. E.g. if it was 980mb in London last week, and if it is 1040mb in London this week, my weight will increase by 6%. Thus if you weighed 170lb last week, you will weigh 180lb this week. Does that make more sense?
Title: Re: Increased gravity at the poles?
Post by: stack on November 14, 2018, 07:38:39 PM
Which expert opinion should we believe?

I'm thinking a neutral neighbor.

Apparently the Canadians take their scales and gravity tolerance/compensation/calibration very seriously. They have a whole government application process to make sure specific location gravity is taken into account:

"Calculate gravity tolerance for scales

The gravity tolerance application calculates the change in gravity between two locations in Canada. This helps you find out whether a non-automatic weighing device can be inspected in one geographic location in Canada, and then put into service in another without requiring readjustment."

https://www.ic.gc.ca/eic/site/mc-mc.nsf/eng/lm04890.html
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 14, 2018, 07:51:16 PM
Probably some consumer group got mad and thought that they were being screwed somewhere along the line so the government had to step in an establish a standard that could be enforced. That's one of the reasons the Somigliana Formula is important and is used by people to compensate their equipment for a change in latitude.   

All the 'confusion' perpetrated by an 'unknown' entity on here can really stir the pot and get the posts flying.  Do you suppose that is really an accident?
   
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 14, 2018, 08:11:49 PM
A scale that measures the weight of the atmosphere has already been invented. It is called the "barometer".

Air pressure does not affect the scale trivially. See the following illustration and text:

https://www.artofmanliness.com/articles/fair-or-foul-how-to-use-a-barometer/

Quote
(https://content.artofmanliness.com/uploads/2015/07/what-is-atmospheric-pressure.gif)

Air pressure decreases as altitude increases.

Atmospheric pressure — or barometric pressure — is simply the weight of the air at ground level. It’s a little easier to understand when you think about the concept of water pressure first. As you get deeper in water, the pressure increases. This is because as you descend, the built up weight of the water on top of you increases. In 1 foot of water, you have the weight of that foot of water pressing down on you. In 2 feet of water, you have the weight of an extra foot of water pressing on you. It’s quite logical, really.
Title: Re: Increased gravity at the poles?
Post by: stack on November 14, 2018, 08:26:38 PM
A scale that measures the weight of the atmosphere has already been invented. It is called the "barometer".

Air pressure does not affect the scale trivially.

Sure, but are we talking about being at 18,000' versus sea level or at a pole versus the equator?
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 14, 2018, 08:45:40 PM
A scale that measures the weight of the atmosphere has already been invented. It is called the "barometer".

Air pressure does not affect the scale trivially.

Sure, but are we talking about being at 18,000' versus sea level or at a pole versus the equator?

The difference between those two locations isn't necessarily as radical.

The point is that farcical promotional stunts are being presented as fact, without control for other variables.
Title: Re: Increased gravity at the poles?
Post by: edby on November 14, 2018, 09:01:22 PM
The point is that farcical promotional stunts are being presented as fact, without control for other variables.
How is this relevant to your claim that change in atmospheric pressure is the primary cause of the 0.5% increase in weight at the pole? And how do you meet the objection that the same change in atmospheric pressure in London has no such impact on weight? Something has to give here, Tom.
Title: Re: Increased gravity at the poles?
Post by: Bobby Shafto on November 14, 2018, 09:07:19 PM
A scale that measures the weight of the atmosphere has already been invented. It is called the "barometer".
Not quite, but it's a good point. You can derive a measure of weight of the atmosphere from a barometer reading. You can also derive a buoyant force figure from a barometer reading.

When air pressure goes up, the weight of the atmosphere does too. But then so does the buoyant force.
When air pressure goes down, the weight of the atmosphere is less, but then so is the buoyant force.

It's an error to apply the weight of the atmosphere alone. Air pressure (measured by a barometer) is in all directions. There's a vector down (weight from above pushing down) and a vector up (buoyancy pushing up from below). It's the net that contributes to an object's weight.

Forces from the side cancel out, but if they (and above/below forces) cause changes in volume of the object, then that changes the net air pressure equation also.

Flatly stating air pressure is the reason for an object having greater measured weight at the poles than at the equator as the 2nd post in this topic claims is flawed because it ignores buoyancy (as does stating that a barometer measures weight of the atmosphere without acknowledging it measures the opposing forces as well). 

Title: Re: Increased gravity at the poles?
Post by: RonJ on November 14, 2018, 10:05:49 PM
Let’s say you take a friendly Gnome to the South Pole and weigh him.  You get the reading of 309.82 grams.  Now you are a total skeptic and are worried about the air pressure altering the real reading, so you wave your magic wand and suck out all the air in the atmosphere.  Now the effects of buoyancy of the air go away and the friendly Gnome now only weighs 309.74 grams. You are not measuring the Gnome against a vacuum anyway, only against the earth’s gravity and a small variation in atmospheric pressure.   You can do all the ‘rope-a-doping’ you want, but the observed facts will remain the same.  The biggest effects on the weight of the Gnome will be the uneven force of gravity on the earth.  Atmospheric effects are negligible and is like the water level effects of ‘pissing in a pool’.   Of course if you don’t believe in the earth’s gravity the whole thing is moot and you have to come up with another explanation for the well documented and observed measurements. 
Title: Re: Increased gravity at the poles?
Post by: LoveScience on November 15, 2018, 11:17:31 AM
Basing my answer purely on the text of the original question, yes you would experience an increased gravitational effect at the poles because the effect of centrifugal force (acting to oppose gravity which gives us our impression of weight) diminishes.

Therefore your weight would be greatest at the equator and least at the poles.
Title: Re: Increased gravity at the poles?
Post by: LoveScience on November 15, 2018, 11:21:15 AM
Sorry! disregard previous.  I got distracted while typing.  Your weight would be greatest at the poles (due to a lack of centrifugal force since you are effectively spinning on the spot if standing exactly on rotation axis) and least at the equator because the effect of centrifugal force is greatest at the equator.
Title: Re: Increased gravity at the poles?
Post by: edby on November 15, 2018, 11:50:40 AM
Sorry! disregard previous.  I got distracted while typing.  Your weight would be greatest at the poles (due to a lack of centrifugal force since you are effectively spinning on the spot if standing exactly on rotation axis) and least at the equator because the effect of centrifugal force is greatest at the equator.
Well it would be on the globe-earth hypothesis. However on the FE Universal Acceleration hypothesis, where the world's surface is an approximately flat plane, accelerating upwards at 9.81 ms^2, 'gravity' would be constant at all locations.

Tom's hypothesis above is that the measured differences are due to changes in atmospheric pressure, not gravity.
Title: Re: Increased gravity at the poles?
Post by: edby on November 15, 2018, 11:59:15 AM
Let’s for the moment concede Tom’s objection to relative (i.e. spring based) gravimeters, and consider how absolute gravimeters work. This (https://scintrexltd.com/wp-content/uploads/2017/03/MgL_A10-Brochure.pdf) outlines how an absolute gravimeter works.

Quote
The A10 operates by using a free-fall method. An object is dropped inside a vacuum chamber and its position is monitored very accurately using a laser interferometer.

Note that if the object is dropped in a vacuum, any objection about air pressure is irrelevant.

If you look at research using the A10, it is accurate to within a few microgals. A gal (named after Galileo) is a unit of acceleration defined as 1 centimeter per second squared (1 cm/s2). One microgal is clearly a very small amount, so absolute gravimeters are extremely high precision instruments.
Relative gravimeters are mostly used for work in the field, due to expense and portability. However they can be calibrated to an absolute gravimeter, as the paper below explains.
Quote
https://www.geos.ed.ac.uk/~hcp/gravity/grav_intro.pdf It is possible to build an instrument that measures g directly. Such an instrument is called an absolute gravity meter and is large, unwieldy and expensive. For field surveys it is more usual to use a relative gravity meter. These are cheaper, smaller and more robust. But they do not measure the absolute value of g. They can only measure the differences in g between one place and another. Relative gravity meters are essentially a mass hung on a spring: if you go to somewhere where gravity is a bit larger, the spring stretches a bit more. The extra stretch is tiny: to measure it, we pull on the spring with a micrometer screw to restore the mass to the original position. Levers are used to make the system more sensitive and the whole mechanism is enclosed in a temperature-controlled box to prevent changes in temperature from affecting the results.

If Tom is correct, we have to make implausible assumption that while masses of research has been done using both forms of gravimeter, no one has bothered to check whether acceleration due to gravity is higher at the poles.
Title: Re: Increased gravity at the poles?
Post by: LoveScience on November 15, 2018, 01:25:17 PM
Quote
Well it would be on the globe-earth hypothesis. However on the FE Universal Acceleration hypothesis, where the world's surface is an approximately flat plane, accelerating upwards at 9.81 ms^2, 'gravity' would be constant at all locations.


Well in that case that is another point in favour of the globe-earth hypoethesis then. I guess it all depends on your own point of view. Ignoring Earth rotation and any effects due to the atmosphere. On a body of the mass of the Earth, gravitational acceleration is a constant as it only depends on mass (F=mg) to quote Newtons 2nd Law.
Title: Re: Increased gravity at the poles?
Post by: edby on November 15, 2018, 04:45:47 PM
See the table below which I sourced from http://www.physics.montana.edu/demonstrations/video/1_mechanics/demos/localgravitychart.html

There are a couple of anomalies, but it follows a straight line trend implying a difference of 0.5% between observed acceleration at equator and poles.

I don't know how the numbers were computed. If using a relative gravimeter, then perhaps Tom is right, although it defies belief that the smart people who devised these experiments missed something as obvious as atmospheric pressure. If an absolute gravimeter, then Tom is flat out wrong, and UA with it.

City, Acceleration, Abs lat
Quito, 9.7724, 0.1807
Singapore, 9.7814, 1.3521
Bogota, 9.7799, 4.711
Djakarta, 9.7814, 6.1805
Caracas, 9.7829, 10.4806
Lima, 9.7829, 12.0464
Manila, 9.7844, 14.5995
Guatemala City, 9.7844, 14.6349
Brasilia, 9.7889, 15.8267
La Paz, 9.7844, 16.4897
Mexico City, 9.7799, 19.4326
Port Louis, 9.7859, 20.1609
Hong Kong, 9.8099, 22.3964
Riyad, 9.7904, 24.7136
Taipei, 9.7904, 25.033
Johannesburg, 9.7919, 26.2041
Manamah, 9.7904, 26.2285
Kuwait, 9.7919, 29.3117
Panama City, 9.7814, 30.1588
Dallas, 9.7949, 32.7767
Baghdad, 9.7964, 33.3152
Santiago, 9.7979, 33.4489
Atlanta, 9.7964, 33.749
Sydney, 9.7979, 33.8688
Beirut, 9.7964, 33.8938
Rabat, 9.7964, 33.9716
Los Angeles, 9.7979, 34.0522
Buenos Aires, 9.7979, 34.6037
Montevideo, 9.7964, 34.9011
Mishima, 9.7979, 35.1184
Nicosia, 9.7979, 35.1856
Tunis, 9.7799, 36.8065
San Jose, 9.7829, 37.3382
Seoul, 9.7994, 37.5665
San Francisco, 9.7994, 37.7749
Athens, 9.8009, 37.9838
Lisbon, 9.8039, 38.7223
Ankara, 9.8024, 39.9334
Philadelphia, 9.8024, 39.9526
Madrid, 9.8024, 40.4168
New York, 9.8024, 40.7128
Wellington, 9.8039, 41.2865
Chicago, 9.8024, 41.8781
Detroit, 9.8039, 42.3314
Boston, 9.8039, 42.3601
Toronto, 9.8054, 43.6532
Bucharest, 9.8054, 44.4268
Ottawa, 9.8069, 45.4215
Montreal, 9.8069, 45.5017
Bern, 9.8084, 46.948
Budapest, 9.8069, 47.4979
Vienna, 9.8099, 48.2082
Vancouver, 9.8099, 49.2827
Prague, 9.8114, 50.0755
Brussels, 9.8114, 50.8503
Dusseldorf, 9.8129, 51.2277
London, 9.8144, 51.5074
Swider, 9.8159, 51.8986
Amsterdam, 9.8129, 52.368
Copenhagen, 9.8159, 55.6761
Stockholm, 9.8189, 59.3293
Oslo, 9.8189, 59.911491
Helsinki, 9.8189, 60.1699
Anchorage, 9.8189, 61.2181



Title: Re: Increased gravity at the poles?
Post by: RonJ on November 15, 2018, 05:32:46 PM
A relative or absolute gravimeter really doesn't matter.  In the worst case the measurements obtained are down in the millionths category of whatever measurement units you happen to be talking about.  There are gravimeters used on ships and on aircraft.  All this equipment has been designed and used by scientists and engineers and all the possible corrections have been accounted for.  The oil companies use this equipment in their prospecting efforts along with the mining companies.  If the technology didn't work they wouldn't be buying this equipment.  Now with the new MEMS technology I would expect to see some useful equipment available in you iPhone sometime in the future.  I don't know what it would be used for, however.  A story I saw was that a company had a absolute gravimeter so sensitive that they could tell when the snow was removed off the roof of the building they were in.  The bottom line is everything is down to a 'gnats ass' and all you are arguing about is how many pimples are on that ass.  The Kern scale experiment was a promotional thing and not a real scientific experiment.  That doesn't mean that the results are not valid.  The results are just are not anywhere as accurate as they could be if the proper equipment was brought to the scene. Many absolute gravimeters (from many countries) were brought together at a single location and the results compared.  The arguments were down to a millionth of a millionth.  These gravimeters are spread out all over the world and are producing readings on a regular basis.  No matter what UA, is not a viable argument unless it can be reworked to explain all the well documented results from scientists from countless countries that have measured a variation in the earth's gravity and can be explained by the rotating round earth paradigm. 
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 15, 2018, 05:41:36 PM
If you want to claim accuracy on an experiment then you need to demonstrate that all variables were accounted for, and that it was properly controlled. All variables were not accounted for with the gnome and spring scale experiment.

Nonetheless, no gravimetric discrepancy would disprove UA. You would need to show that there are no slight gravimetric disturbances above or below the earth. This is why this topic is a dead end discussion-wise.
Title: Re: Increased gravity at the poles?
Post by: edby on November 15, 2018, 05:43:08 PM
If you want to claim accuracy on an experiment then you need to demonstrate that all variables were accounted for. All variables were not accounted for with the gnome and spring scale experiment.

Nonetheless, no gravimetric discrepancy would disprove UA. You would need to show that there are no slight gravimetec disturbances above or below the earth, and this is why this topic is a dead end discussion-wise.
This is what logicians call the 'nuclear option'. Whatever carefully observed observation is produced, will always be open to the objection that there is some completely unknown force which distorts the observations. It could be leprechauns, for example.

What evidence if any would you accept as 'disproving' UA then Tom? Also, if you would refuse to accept any evidence whatsoever o/a of your faith in UA, how is your belief distinguishable from a religious or superstitious belief?
Title: Re: Increased gravity at the poles?
Post by: JCM on November 15, 2018, 05:47:55 PM
If you want to claim accuracy on an experiment then you need to demonstrate that all variables were accounted for. All variables were not accounted for with the gnome and spring scale experiment.

Nonetheless, no gravimetric discrepancy would disprove UA. You would need to show that there are no slight gravimetric disturbances above or below the earth. This is why this topic is a dead end discussion-wise.

You are going to dismiss Edby’s data showing a straight trend line with latitude just like that?  It’s a trend line to 4 decimals! What possible other variations could create that trend line? You are the one discounting the data, you need to show what’s wrong with that data. 
Title: Re: Increased gravity at the poles?
Post by: inquisitive on November 15, 2018, 05:50:15 PM
If you want to claim accuracy on an experiment then you need to demonstrate that all variables were accounted for, and that it was properly controlled. All variables were not accounted for with the gnome and spring scale experiment.

Nonetheless, no gravimetric discrepancy would disprove UA. You would need to show that there are no slight gravimetric disturbances above or below the earth. This is why this topic is a dead end discussion-wise.
Have you discussed your concerns with any scientific institutions?
Title: Re: Increased gravity at the poles?
Post by: edby on November 15, 2018, 05:59:31 PM
Sadly Tom has pressed the nuclear button, but here is some other data I have worked on anyway, now that I have done it. The graph below charts acceleration against latitude from about 153,000 locations in the UK, published by the British Geological Society. Includes free air adjustments (for height) and Bouguer correction (for terrain).

Like the data above, it is consistent with an 0.5% (actually 0.7%) increase in acceleration per 90 degrees.

(http://www.logicmuseum.com/w/images/3/3a/Geo_survey_acceleration.jpg)

However, any data or evidence whatsoever can be rejected on one simple assumption, namely that it contradicts UA.
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 15, 2018, 06:24:11 PM
No one said that all the variables were accounted for in gnome experiment.  It was just a promotional thing for Kern.  What isn't a promotional thing is all the measurements (world wide) made in a laboratory by scientists with all the variables accounted for down to a gnat's ass.  The absolute gravimeters used have been constructed in various ways by engineers and scientists from countless countries.  Many of those instruments were brought to a common location and their readings compared.  Differences were in the category of a few millionths of a millionth.  How much closer do you want to get?  If you don't believe these facts please tell us all the variables you need accounting for, the standards and the desired accuracy you need.  My guess is that the existing gravimeters already meet those specifications and the data is available.  Would it help if you could personally witness an actual measurement.  If that wouldn't help please tell us what would.
Title: Re: Increased gravity at the poles?
Post by: edby on November 15, 2018, 06:27:06 PM
No one said that all the variables were accounted for in gnome experiment.  It was just a promotional thing for Kern.  What isn't a promotional thing is all the measurements (world wide) made in a laboratory by scientists with all the variables accounted for down to a gnat's ass.  The absolute gravimeters used have been constructed in various ways by engineers and scientists from countless countries.  Many of those instruments were brought to a common location and their readings compared.  Differences were in the category of a few millionths of a millionth.  How much closer do you want to get?  If you don't believe these facts please tell us all the variables you need accounting for, the standards and the desired accuracy you need.  My guess is that the existing gravimeters already meet those specifications and the data is available.  Would it help if you could personally witness an actual measurement.  If that wouldn't help please tell us what would.
You are missing Tom's point, which is that the observed variation is explained by some other unknown force above or below the earth. You start with the assumption that UA is true. It follows that any observation apparently contradicting UA must have some unknown explanation that removes the contradiction. For example, the observed increase in acceleration as we move to the poles could be explained by Dark Matter at the perimeter.
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 15, 2018, 06:45:27 PM
Ok, I went off the deep end and answered too quickly.  Let's try this;  Forget gravity altogether. FET doesn't allow gravitational effects of the earth itself anyway.  The measurements made were of the actual acceleration due to UA, not gravity.  Of course all the variables have been accounted for and everything was done in a laboratory setting. The problem is that these laboratories are located all over the world and not just at the poles.  Under the UA theory you can't tolerate too much of any variance in acceleration world wide or the earth would fold in on itself.  Of course that isn't what has been measured.  If you want to play the 'dark matter' card then that can be measured as well.  Anything that has the power to accelerate a mass can be measured.  I don't think anyone has seen any anomalous effects in this regard.
Title: Re: Increased gravity at the poles?
Post by: edby on November 15, 2018, 06:58:03 PM
Ok, I went off the deep end and answered too quickly.  Let's try this;  Forget gravity altogether.  The measurements made were of the actual acceleration due to UA, not gravity.  Of course all the variables have been accounted for and everything was done in a laboratory setting. The problem is that these laboratories are located all over the world and not just at the poles.  Under the UA theory you can't tolerate too much of any variance in acceleration world wide or the earth would fold in on itself.  Of course that isn't what has been measured.  If you want to play the 'dark matter' card then that can be measured as well.  Anything that has the power to accelerate a mass can be measured.  I don't think anyone has seen any anomalous effects in this regard.
Roughly correct, but strictly speaking the data simply measures observed acceleration at different points in the UK (and the world). Perhaps I shouldn't have included the adjustments, since those require an element of theory.

The question is how to explain the functional relationship between observed acceleration and latitude. Globe-earth theory is the simplest. UA on its own doesn't work, given its basis in the earth's being approximately a flat and rigid plane. So we need an addition to UA, namely some unknown force, perhaps Dark Energy, which acts increasingly as objects approach the poles. Or leprechauns.

The problem with the Dark Energy hypothesis is it requires the very phenomenon that UA was designed to avoid, namely action at a distance. If we accept that, why not ditch UA altogether and make Dark Energy explain everything? Or why not just call it 'gravity'?
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 15, 2018, 07:16:45 PM
I could see that a single measurement point of one of the gravimeters could get some kind of an anomalous reading that couldn't be accounted for.  With all the measurement labs out there (worldwide) making frequent measurements, any variations in readings would be seen and any small disturbances in the earths gravity due to transient events would be seen.  No it's just not possible to dismiss the theory of gravity for such a minor reason.  Besides, the differences in the readings between spaced out gravimeters are NOT slight for an instrument that can measure the force down to a millionth of a millionth.   If you hit me with a grain of rice, I might not even feel it.  I believe that if a gnat got hit with that same grain of rice the it would be knocked silly or killed.  You have to keep everything in perspective.

I believe that the idea to avoid gravity in the FET paradigm is to avoid another problem.  If the earth were flat and you had gravity then a plum bob wouldn't be at right angles to the earth anywhere except at the North Pole.  The further out you got, the more the bob would be out of level.  All the other problems are flowing from the first flat earth assumption.  Like the old saying 'what a tangled web we weave when we first try to deceive'. 
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 15, 2018, 07:26:18 PM
The problem with the Dark Energy hypothesis is it requires the very phenomenon that UA was designed to avoid, namely action at a distance. If we accept that, why not ditch UA altogether and make Dark Energy explain everything? Or why not just call it 'gravity'?

Neither of those solutions answer the astronomical coincidence that inertial equivalence is exactly equal to gravitational mass equivalence.

https://arxiv.org/ftp/physics/papers/0004/0004027.pdf

(https://i.imgur.com/2WkcP5Z.png)

Also watch this video at the 3h4m16s mark for 15 minutes:

https://www.youtube.com/watch?v=DmGwZeSP5WY&feature=youtu.be&t=3h4m16s
Title: Re: Increased gravity at the poles?
Post by: markjo on November 15, 2018, 08:30:23 PM
If you want to claim accuracy on an experiment then you need to demonstrate that all variables were accounted for, and that it was properly controlled. All variables were not accounted for with the gnome and spring scale experiment.

Nonetheless, no gravimetric discrepancy would disprove UA. You would need to show that there are no slight gravimetric disturbances above or below the earth. This is why this topic is a dead end discussion-wise.

Actually, there are slight gravimetric variations below the earth that correspond to the varying densities of various geologic formations.  As mentioned before, surveys of these slight gravitmetric variations have real world applications in mineral and resource mining.  This is a real world application that GR explains quite nicely, but UA can't.
Quote from: https://www.geologyforinvestors.com/gravity-surveys/
The ability for rock density to be detected using gravity variations is the basis for the use of Gravity Surveys in mineral exploration.  Rock below the earth’s surface is not homogeneous. It is composed of material of different densities, both horizontally  and vertically. The density of rock varies with the amount of mass contained within them. Denser rocks contain more mass and therefore exert a greater force of gravitational attraction.
Title: Re: Increased gravity at the poles?
Post by: Tom Bishop on November 15, 2018, 09:26:47 PM
If you want to claim accuracy on an experiment then you need to demonstrate that all variables were accounted for, and that it was properly controlled. All variables were not accounted for with the gnome and spring scale experiment.

Nonetheless, no gravimetric discrepancy would disprove UA. You would need to show that there are no slight gravimetric disturbances above or below the earth. This is why this topic is a dead end discussion-wise.

Actually, there are slight gravimetric variations below the earth that correspond to the varying densities of various geologic formations.  As mentioned before, surveys of these slight gravitmetric variations have real world applications in mineral and resource mining.  This is a real world application that GR explains quite nicely, but UA can't.
Quote from: https://www.geologyforinvestors.com/gravity-surveys/
The ability for rock density to be detected using gravity variations is the basis for the use of Gravity Surveys in mineral exploration.  Rock below the earth’s surface is not homogeneous. It is composed of material of different densities, both horizontally  and vertically. The density of rock varies with the amount of mass contained within them. Denser rocks contain more mass and therefore exert a greater force of gravitational attraction.

Those companies who promise to be able to use gravimeters to discover oil and mineral deposits on your property are actually snake oil men. Look up the "Great Oil Sniffer Hoax".  These days they use multiple methods to search for oil and mineral deposits, some valid and some not. Gravimeters were never proven to be valid for that purpose.

https://www.researchgate.net/publication/326920804_The_Great_Oil_Sniffer_Hoax

Quote
The Great Oil Sniffer Hoax

Since the early days of petroleum exploration, the industry has met diviners and dowsers who, by using esoteric techniques, simple devices or sophisticated artifacts designed by themselves, have tried to fool companies by claiming they were able to detect oil in the subsurface. In France, during the late 1970s, two eccentric inventors claimed they could directly detect oil in the subsurface from an exceptional device mounted on board an airplane, resulting in one of the most famous frauds in petroleum exploration history.

Of course, these forms of divination are not exclusive of oil exploration and they have been a subject of discussion and controversy for many years.

From your article "The ability for rock density to be detected using gravity variations is the basis for the use of Gravity Surveys in mineral exploration"

This is a promotional piece designed to promoting tools of the diviners and dowsers, whose science is very much controversial. They promise get rich quick mineral and resource finding schemes for a small investment... Just look at the url of your article: geologyforinvestors.com

We have had this discussion a number of times before, and you continue to link to these cons.
Title: Re: Increased gravity at the poles?
Post by: HorstFue on November 15, 2018, 09:37:57 PM
E.g. if it was 980mb in London last week, and if it is 1040mb in London this week, my weight will increase by 6%. Thus if you weighed 170lb last week, you will weigh 180lb this week. Does that make more sense?
That does not make more sense at all, unless nonsense.
According good old Archimedes (https://en.wikipedia.org/wiki/Archimedes%27_principle):
"the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces"
Don't argue about "fluid", later in the article the same is applied to a dirigible in air.

What is the volume of a human body? Density of a human body is close to water, 1000kg/m³. A human with 100kg so has a volume of about 0.1m³.
Air density is 1.225kg/m³. Air density changes directly proportional to pressure (p*V = const.). So increasing pressure by 6%, increases density by 6%. So the total weight change, the change of the weight of the displaced air, is 1.225kg/m³*0.1m³*0.06 = 0.007kg.
Title: Re: Increased gravity at the poles?
Post by: edby on November 15, 2018, 10:09:55 PM
E.g. if it was 980mb in London last week, and if it is 1040mb in London this week, my weight will increase by 6%. Thus if you weighed 170lb last week, you will weigh 180lb this week. Does that make more sense?
That does not make more sense at all, unless nonsense.
I was paraphrasing an argument made by Tom, who claims that increasing atmospheric pressure increases weight. Are you saying his argument is nonsense?
Title: Re: Increased gravity at the poles?
Post by: edby on November 15, 2018, 10:20:23 PM
Nonetheless, no gravimetric discrepancy would disprove UA.
No gravimetric discrepancy would disprove it was caused by leprechauns.

Science does not and cannot prove or disprove anything. Science proffers the most economical hypothesis to explain the observations.
Title: Re: Increased gravity at the poles?
Post by: edby on November 15, 2018, 10:28:09 PM
And as Tom says, gravimetrics has indeed been discussed here before.

https://forum.tfes.org/index.php?topic=2175.0

https://forum.tfes.org/index.php?topic=7639.0

Title: Re: Increased gravity at the poles?
Post by: RonJ on November 15, 2018, 10:36:44 PM
From the Wiki:
Celestial Gravitation is a part of some Flat Earth models which involve an attraction by all objects of mass on earth to the heavenly bodies. This is not the same as Gravity, since Celestial Gravitation does not imply an attraction between objects of mass on Earth. Celestial Gravitation accounts for tides and other gravimetric anomalies across the Earth's plane.

I am surprised that Celestial Gravitation wasn’t cited as a cause for some of the gravimetric anomalies that were measured by the absolute gravimeters.  The citation also implies that there is no gravitational attraction between two masses on the earth.  Any gravitational attraction will only be between an earthly mass, like water, and an unspecified heavenly body at an unspecified distance.  This would mean that the ‘heavenly body’ would have to be endowed with a property of gravitational attraction between itself and a mass on the earth.  Is this hypothesis correct?

It would then be logical to assume that these ‘heavenly bodies’ are in motion since there is a variable attraction causing the variation of tides on the earth.  Since the tide are on a regular schedule that means the heavenly body must be on a regular schedule as well.  Given all that you should then be able to put a gravimeter in a fixed location on the earth as see a regular and significant reading change that would coincide roughly with the change in tides.  Of course, this isn’t what is being observed here on earth.    Where did my thesis go wrong?
Title: Re: Increased gravity at the poles?
Post by: edby on November 15, 2018, 11:03:46 PM
From the Wiki:
Celestial Gravitation is a part of some Flat Earth models which involve an attraction by all objects of mass on earth to the heavenly bodies. This is not the same as Gravity, since Celestial Gravitation does not imply an attraction between objects of mass on Earth. Celestial Gravitation accounts for tides and other gravimetric anomalies across the Earth's plane.

I am surprised that Celestial Gravitation wasn’t cited as a cause for some of the gravimetric anomalies that were measured by the absolute gravimeters.  The citation also implies that there is no gravitational attraction between two masses on the earth.  Any gravitational attraction will only be between an earthly mass, like water, and an unspecified heavenly body at an unspecified distance.  This would mean that the ‘heavenly body’ would have to be endowed with a property of gravitational attraction between itself and a mass on the earth.  Is this hypothesis correct?

It would then be logical to assume that these ‘heavenly bodies’ are in motion since there is a variable attraction causing the variation of tides on the earth.  Since the tide are on a regular schedule that means the heavenly body must be on a regular schedule as well.  Given all that you should then be able to put a gravimeter in a fixed location on the earth as see a regular and significant reading change that would coincide roughly with the change in tides.  Of course, this isn’t what is being observed here on earth.    Where did my thesis go wrong?
Clearly then the force which is a function of latitude must be different from the force which causes tides, for the reasons you suggest. Why not a pool of Dark Energy surrounding the earth behind the ice wall? Or is there a problem here that the force does not act in a North-South direction? (I am assuming the monopole map here).

This is proving quite a challenge but I am thinking about it.

Another explanation could be that the disc-earth really is accelerating faster at the rim than at the centre, but we don't notice this because of a distortion of space-time. The earth appears flat, but is really the inside surface of an enormous cup-shaped object, ever-increasing in height, with light curving around the inside surface. It looks flat, but isn't.
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 16, 2018, 01:01:06 AM
Since according to the Wiki a property of Celestial Gravitation that allows an attraction of things on the earth to the unspecified Heavenly body (moon and the stars I see in another part of the wiki), can I use the standard universal gravitation equation to measure that attractive force?  Do you believe in the Davis Model?  If that is an invalid equation for Celestial Gravitation is there a specified equation for this force?  If there’s no gravitational attraction between any two objects on earth, then the Clairaut experiment is invalid and either the measuring equipment is malfunctioning, or the Heavenly bodies are the cause of the difference in force measured.  Since there are hundreds of absolute gravimeters in service and they have all been checked and compared extensively I am going to hypothesize that not all of them are defective and most of them are providing valid readings of some kind of force. 

Since Universal Acceleration provides for a constant acceleration of 9.8 meters per second squared, you can just subtract that from any reading you get on a gravimeter because that is the part measured due exclusively to UA.  If you do that you will find some negative numbers.  Readings are a bit higher at the poles and a bit lower at the equator.  Since the earth is flat and non-rotating there can’t be a factor due to centrifugal force.  Is maybe the wiki figure for UA of 9.8 a bit too high?  Is there some kind of Celestial Repulsive force at work?  Is dark energy causing the anomalous readings?  All I’m trying to do is answer some basic questions abut the earth and the heavenly bodies.  I can see how you could use the variations of the gravimeter readings along with their position to get a reading on at least the center of mass of the Heavenly bodies causing the reading anomalies.   
Title: Re: Increased gravity at the poles?
Post by: edby on November 17, 2018, 03:30:14 PM
Here is a tidier chart of the same data (from the British Geological Survey)

(http://www.logicmuseum.com/w/images/4/46/Geo_survey_acceleration_2.jpg)

I used all of the data this time. Instead of taking intervals on the data set, I used all of it but averaged bucketed over 0.01 degrees of latitude, giving just 1,000 data points. I also used a proper x-y chart. Finally I added a trend line using least squares method. This suggests an 0.84% change in gravity from equator to N pole, but remember that is an extrapolation from UK data only, within UK latitudes.

The trend line does not fit perfectly – note the significant deviation around 57o latitude.
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 17, 2018, 06:20:55 PM
The readings above pretty much matches the Somigliana formula.  I put a sampling of the numbers into my MathCad program and everything matches up closely.  Of course there are gravitational survey results from all over the globe conducted by countless countries each conducting independent investigations.  Results are available for a lot of them and will show a correlation between measured gravitation and latitude.  Anything that matches the Somigliana formula would indicate that the earth is rotating and is not a perfect spheroid.  The acceleration due to rotation, height, and the earth not being a perfect sphere are all accounted for.  You can be sure that the vast majority of the gravimeters used were well calibrated and used by trained people.  My opinion is that in order to believe FET they will have to come up with a viable story that will account for a huge amount of actual measurements made by observers from all over the world. 
Title: Re: Increased gravity at the poles?
Post by: LoveScience on November 17, 2018, 11:54:04 PM
And no doubt they will.... one way or another!
Title: Re: Increased gravity at the poles?
Post by: junker on November 17, 2018, 11:56:05 PM
And no doubt they will.... one way or another!

Refrain from low-content posting in the upper fora (this includes “me too” posts where it’s just an agreement with a previous post). No warning yet, but please read the rules.
Title: Re: Increased gravity at the poles?
Post by: edby on November 18, 2018, 10:30:25 AM
And here is the same type of data for Africa between latitudes of 35 and 17 South. Note I have NOT corrected for elevation so far. As we know, celestial gravitation (the attraction of earthly bodies to sun, moon or stars) will interfere with universal acceleration.

Note again how acceleration increases as we move from the equator. The cause of this phenomenon is as yet unknown. Tom Bishop says it could be a form of gravitation arising from objects above or below the earth. I have surmised it is caused by a form of Dark Energy.

(http://www.logicmuseum.com/w/images/3/3c/Africa_acceleration.jpg)

Data provided by National Centers for Environmental Information.
Title: Re: Increased gravity at the poles?
Post by: AllAroundTheWorld on November 18, 2018, 04:56:00 PM
If you want to claim accuracy on an experiment then you need to demonstrate that all variables were accounted for, and that it was properly controlled.
Would you say that Rowbotham’s experiments are rigorous enough to make that claim for?
Title: Re: Increased gravity at the poles?
Post by: RonJ on November 18, 2018, 06:07:57 PM
The graph of all the data points are about what I would expect.  The works of Somigliana outlines the mathematical expected differences in gravity at different latitudes.  Corrections for the differences between the surface of the earth and the center of gravity in the oblate spheroid are accounted for.  Additionally there are also corrections for the expected differences in centrifugal forces as well.   Of course the data is a bit noisy because it hasn't been corrected for the differences in altitude yet.  The graph is an example of good scientific methods.  Formulate a hypothesis for the shape of the earth.  Develop an equation based upon the expected variables.  Make thousands of measurements in the field and collect all the data being as careful as you can to reduce error.  Compare that data with the expected values based upon the equations you have. If there is a good match, then it is a good indication that your thesis has some merit.  Of course if another theory and mathematical equation can be developed that also will matched the actual observed data then there will be a strong basis for a debate.  If there is another theory and equation for the flat earth paradigm now is the time to bring it forth so it can be compared with the actual collected data to see if there's also a reasonable match.
Title: Re: Increased gravity at the poles?
Post by: LoveScience on November 19, 2018, 10:20:46 PM
Entirely agree with all of the above.
Title: Re: Increased gravity at the poles?
Post by: junker on November 19, 2018, 10:45:19 PM
Entirely agree with all of the above.

Please refrain from "me too" posts in the upper fora. They do not add anything to the discussion and are considered low-content. Warned.
Title: Re: Increased gravity at the poles?
Post by: LoveScience on November 19, 2018, 11:41:07 PM
Are we not allowed to state when we agree with the comments from another member then.  Or just not when it happens to not correspond with the views of the FES?  All part of free speech in my view but if that contravenes your rules then by all means cancel my membership!
Title: Re: Increased gravity at the poles?
Post by: junker on November 20, 2018, 12:08:31 AM
Are we not allowed to state when we agree with the comments from another member then.  Or just not when it happens to not correspond with the views of the FES?  All part of free speech in my view but if that contravenes your rules then by all means cancel my membership!

You are allowed to agree with anyone you want to. Just add something more to the post so it actually contributes to the conversation (and therefore is not a low-content post). I am not sure why this recent batch of new users (you included) seem to struggle with following a few simple rules without suggesting you are being oppressed, or acting like your free speech is being inhibited.

Also, you can cancel your own membership at any time. Anyway, if you are going to post again, I suggest you stick to the topic. I'll refrain from additional warnings for now.
Title: Re: Increased gravity at the poles?
Post by: LoveScience on November 20, 2018, 07:51:24 AM
Well my sincere apologies if I have been in breach of any of your rules. I will ensure I read them again and make every effort to abide. I have no knowledge about any other users for reasons that are obvious but I have only come on here and offer my side of any discussions that I contribute to. 

What I say is based on my 35+ years experience as an amateur astronomer and all I say is true to the best of my knowledge and experience. I will say no more in this particular thread or topic.
Title: Re: Increased gravity at the poles?
Post by: edby on November 24, 2018, 01:09:09 PM
Given the arguments about gravimeter accuracy in another (https://forum.tfes.org/index.php?topic=11397.msg174168) thread, I am posting the theoretical correspondence between latitude and local gravity at height zero at the given latitude.
The point is to highlight how large is the theoretical difference between local gravity at the equator and at the pole, in terms of the units used in gravimetry.

The figures are in microGal, i.e. one millionth of 1 cm per secsq. Note centimetres not metres, hence the usually quoted number of 9.81 is 981 Gal.
Then note the difference in microG between equator and pole, which is of the order of 5 million, so it is false to say that there is a ‘slight difference’ between gravity at equator and pole.

Modern machines have an error of about 5-10 microG. If you compare actual observations against the theoretical values below, you will find a close correspondence.

I have the formula if anyone is interested.

Latitude   ,   Local gravity microG   ,   Difference
90   ,   983 218 620.6   ,   5 185 920.6
85   ,   983 179 056.6   ,   5 146 356.6
80   ,   983 061 582.4   ,   5 028 882.4
75   ,   982 869 811.6   ,   4 837 111.6
70   ,   982 609 639.3   ,   4 576 939.3
65   ,   982 289 054.2   ,   4 256 354.2
60   ,   981 917 886.0   ,   3 885 186.0
55   ,   981 507 495.9   ,   3 474 795.9
50   ,   981 070 421.6   ,   3 037 721.6
45   ,   980 619 987.7   ,   2 587 287.7
40   ,   980 169 895.9   ,   2 137 195.9
35   ,   979 733 806.6   ,   1 701 106.6
30   ,   979 324 925.7   ,   1 292 225.7
25   ,   978 955 608.7   ,   922 908.7
20   ,   978 636 993.7   ,   604 293.7
15   ,   978 378 672.7   ,   345 972.7
10   ,   978 188 411.1   ,   155 711.1
5   ,   978 071 921.8   ,   39 221.8
0   ,   978 032 700.0   ,   0.0