Offline edby

  • *
  • Posts: 1066
    • View Profile
Re: The Circularity Objection
« Reply #40 on: June 08, 2018, 09:21:19 AM »
I will repeat. So the killer objection from the Flat Earth side is: the method is flawed on account of the earth being a spheroid??
« Last Edit: June 08, 2018, 09:28:05 AM by edby »

Offline Tontogary

  • *
  • Posts: 431
    • View Profile
Re: The Circularity Objection
« Reply #41 on: June 08, 2018, 10:28:22 AM »
I will repeat. So the killer objection from the Flat Earth side is: the method is flawed on account of the earth being a spheroid??

I wouldn’t like to assume what objections the Re supporters might put up, but that is one of the objections that i have seen used a number of times.

If the method/results that you are trying to show are dependent on the world being spherical, then the results must be flawed, and therefore are suspect, and not admissible.

However i may be wrong, and as we have not seen many RE supporters on this thread for a while, it is hard to guess what the objection might be. But I would suggest that in order to get any agreement then it would be important to show that the outcome in not reliant upon the earth being a globe in the first place.

Also, if you haven't heard of bronies before, that reflects poorly on your understanding of the world that surrounds you. It's practically impossible not to know about them.

Offline edby

  • *
  • Posts: 1066
    • View Profile
Re: The Circularity Objection
« Reply #42 on: June 08, 2018, 10:41:37 AM »
I will repeat. So the killer objection from the Flat Earth side is: the method is flawed on account of the earth being a spheroid??

I wouldn’t like to assume what objections the Re supporters might put up, but that is one of the objections that i have seen used a number of times.

If the method/results that you are trying to show are dependent on the world being spherical, then the results must be flawed, and therefore are suspect, and not admissible.

However i may be wrong, and as we have not seen many RE supporters on this thread for a while, it is hard to guess what the objection might be. But I would suggest that in order to get any agreement then it would be important to show that the outcome in not reliant upon the earth being a globe in the first place.

I think this confuses two things. (1) The result depends or is reliant on the assumption that the earth is spheroid (2) The results are what they are because the earth is spheroid.

Suppose I take a large beach ball, and mark an ‘equator’ and a ‘north pole’ on it. Then I draw two ‘lines of longitude’ from the pole to the equator line. I measure the angle at the pole, and it is 15 degrees. Then I measure the angles at the equator and find that they are both 90 degrees. So to my astonishment the three angles add up to more than 180 degrees! Shock!

The ‘flat beach ball’ supporter beside me leaps up and down with joy. This proves that my measurement was incorrect or contained an error etc because it ‘was reliant upon’ the assumption that the beach ball was a ball. So I have proved nothing!
« Last Edit: June 08, 2018, 10:44:09 AM by edby »

Offline Tontogary

  • *
  • Posts: 431
    • View Profile
Re: The Circularity Objection
« Reply #43 on: June 08, 2018, 11:00:45 AM »
If the method of measuring distance on the earth requires that the earth be a globe, then that method will be rejected as being flawed, as the earth is not a globe (as shown by EnaG)

It’s hard to find any method which does not have an element of the globe nature of the earth as part of its method, or an adjustment due to the earths shape.

However i think quantifying the adjustment, and therefore the final differences might help


Also, if you haven't heard of bronies before, that reflects poorly on your understanding of the world that surrounds you. It's practically impossible not to know about them.

Offline hexagon

  • *
  • Posts: 192
    • View Profile
Re: The Circularity Objection
« Reply #44 on: June 08, 2018, 11:07:04 AM »
The problem is not to measure a given distance between two points, the problem is to give this measurement a meaning in terms mapping.

Take this example. You measure the distance between two points A and B with a chain. The area between the two points is flat, in the sense that every part of the chain is always perpendicular to a plumb bop.

Now you take a laser at point A at height h above the ground. And you measure the distance to a correspondent point at height h above the ground at B.

On a flat earth both measurements would give the same result. On a spherical earth not. And the discrepancy increases with distance and height.

Now assume you go with your chain to another place, that is equally flat, but about h higher than the first area. Now you will get again a different result on globe earth but not on flat-earth.   

You see, on a flat-earth surveying is quite simple, because a flat-earth follows Euclidean geometry and all our measurement methods are Euclidean. They measure straight lines or assume to measure straight lines.

But a globe follows spherical geometry, therefor you have to correct your measurements to account for that.     

*

Offline Tumeni

  • *
  • Posts: 1379
    • View Profile
Re: The Circularity Objection
« Reply #45 on: June 08, 2018, 11:07:18 AM »
If the method of measuring distance on the earth requires that the earth be a globe, then that method will be rejected as being flawed, as the earth is not a globe (as shown by EnaG)

..but if more than one method is used, and the results from each tally with each other, within reasonable limits of error, and they are all based on globe mechanics .....
==============================
==============================
Pete Svarrior "We are not here to directly persuade anyone ... You mistake our lack of interest in you for our absence."

Tom Bishop "We are extremely popular and the entire world wants to talk to us. We have better things to do with our lives than have in depth discussions with every single curious person. You are lucky to get one sentence dismissals from us"

Offline hexagon

  • *
  • Posts: 192
    • View Profile
Re: The Circularity Objection
« Reply #46 on: June 08, 2018, 11:11:42 AM »
If the method of measuring distance on the earth requires that the earth be a globe, then that method will be rejected as being flawed, as the earth is not a globe (as shown by EnaG)

It’s hard to find any method which does not have an element of the globe nature of the earth as part of its method, or an adjustment due to the earths shape.

However i think quantifying the adjustment, and therefore the final differences might help

But the flaw is in the end not a flaw, it's the solution. All surveys took the shape of the earth into account, the result is a perfectly working map of the world. If they would have taken a flat-earth into account (meaning no spherical corrections), the resulting map would be full of inconsistency and contradictions.

   

Offline Tontogary

  • *
  • Posts: 431
    • View Profile
Re: The Circularity Objection
« Reply #47 on: June 08, 2018, 11:19:30 AM »
I know all that, and i agree with all you say, i am only playing devils advocate a bit here, and trying to think of the objections that may be raised.

As they will.

If there has to be an adjustment made to account for the spherical earth, I agree with it. It will make the spherical earth map more accurate, and confirm our knowledge of the round earth, but I am not the one you need to convince!

Also, if you haven't heard of bronies before, that reflects poorly on your understanding of the world that surrounds you. It's practically impossible not to know about them.

Offline edby

  • *
  • Posts: 1066
    • View Profile
Re: The Circularity Objection
« Reply #48 on: June 08, 2018, 11:21:38 AM »
But a globe follows spherical geometry, therefor you have to correct your measurements to account for that.     
No you don't have to correct your measurements in any way.

I agree that if we want to represent these measurements on a flat surface, we will have to 'correct' them. But the measurements in themselves are perfectly correct.

There seems to be a logical confusion here between

(A) We get result y on the assumption that x is true, therefore x is true

(B) We get result y because x is true, therefore x is true

(A) is clearly invalid, (B) is not.
« Last Edit: June 08, 2018, 11:26:49 AM by edby »

Offline edby

  • *
  • Posts: 1066
    • View Profile
Re: The Circularity Objection
« Reply #49 on: June 08, 2018, 11:22:47 AM »
But the flaw is in the end not a flaw, it's the solution. All surveys took the shape of the earth into account, the result is a perfectly working map of the world. If they would have taken a flat-earth into account (meaning no spherical corrections), the resulting map would be full of inconsistency and contradictions.
Agree, although it wasn't a flaw in the first place. The measurements were correct all along.

If there has to be an adjustment made to account for the spherical earth, I agree with it. It will make the spherical earth map more accurate, and confirm our knowledge of the round earth, but I am not the one you need to convince!
No adjustment required. The measurements are what they are. They have to be 'adjusted' in order to represent them on a flat map, of course.

But a globe follows spherical geometry, therefor you have to correct your measurements to account for that.     
Again, no 'correction' needed, unless the results need to be interpreted on a flat surface.
« Last Edit: June 08, 2018, 11:25:30 AM by edby »

Offline hexagon

  • *
  • Posts: 192
    • View Profile
Re: The Circularity Objection
« Reply #50 on: June 08, 2018, 11:37:55 AM »
But the flaw is in the end not a flaw, it's the solution. All surveys took the shape of the earth into account, the result is a perfectly working map of the world. If they would have taken a flat-earth into account (meaning no spherical corrections), the resulting map would be full of inconsistency and contradictions.
Agree, although it wasn't a flaw in the first place. The measurements were correct all along.

If there has to be an adjustment made to account for the spherical earth, I agree with it. It will make the spherical earth map more accurate, and confirm our knowledge of the round earth, but I am not the one you need to convince!
No adjustment required. The measurements are what they are. They have to be 'adjusted' in order to represent them on a flat map, of course.

But a globe follows spherical geometry, therefor you have to correct your measurements to account for that.     
Again, no 'correction' needed, unless the results need to be interpreted on a flat surface.

I partly disagree. But maybe only, because for me some words have a slightly different meaning.

For me the single measurements as such are obviously correct. If I measure 100m, then this are 100m within the accuracy of the method applied. There is no doubt.

But as soon as you try to combine all your single measurements to a map, you need corrections, if the earth is spherical. It's triangulation, and the angles of triangles only sum up to 180° if the earth is flat.   

Offline edby

  • *
  • Posts: 1066
    • View Profile
Re: The Circularity Objection
« Reply #51 on: June 08, 2018, 11:41:37 AM »
But as soon as you try to combine all your single measurements to a map, you need corrections, if the earth is spherical. It's triangulation, and the angles of triangles only sum up to 180° if the earth is flat.
If you combine them onto a spherical map, what's the problem? A map doesn't have to be flat.

My point is that there is no substantive inaccuracy in the measurements. They will fit perfectly on a spheroid.

Btw the debate from the 18th century onwards was not whether the earth was spherical, that had been known for a long time. The question was whether a line drawn around the poles would be 'longer' than a line drawn around the equator.

The Indian surveyors understood this well, and part of their work was to understand how far the earth differed from a perfect sphere.
« Last Edit: June 08, 2018, 11:43:53 AM by edby »

Offline hexagon

  • *
  • Posts: 192
    • View Profile
Re: The Circularity Objection
« Reply #52 on: June 08, 2018, 11:43:09 AM »
I know all that, and i agree with all you say, i am only playing devils advocate a bit here, and trying to think of the objections that may be raised.

As they will.

If there has to be an adjustment made to account for the spherical earth, I agree with it. It will make the spherical earth map more accurate, and confirm our knowledge of the round earth, but I am not the one you need to convince!

I know, the usual objection is, that you take a round earth into account and therefor you get nice globe. But this objection is wrong, you only get a nice globe, because your measurements were done on a globe. If the earth would be flat and you would assume a globe you would end up with a completely distorted globe.

Its the inverse problem the flat-earth believers have if they try to construct a flat map...   

Offline hexagon

  • *
  • Posts: 192
    • View Profile
Re: The Circularity Objection
« Reply #53 on: June 08, 2018, 11:46:12 AM »
But as soon as you try to combine all your single measurements to a map, you need corrections, if the earth is spherical. It's triangulation, and the angles of triangles only sum up to 180° if the earth is flat.
If you combine them onto a spherical map, what's the problem? A map doesn't have to be flat.

Yes, if you directly project the measurements onto a model of the globe earth, then it will directly fit. But flat-earthers are right if they say, no one is carrying around globes for navigation, everyone uses flat maps.

Offline edby

  • *
  • Posts: 1066
    • View Profile
Re: The Circularity Objection
« Reply #54 on: June 08, 2018, 11:56:03 AM »
Yes, if you directly project the measurements onto a model of the globe earth, then it will directly fit. But flat-earthers are right if they say, no one is carrying around globes for navigation, everyone uses flat maps.
But they would have to concede the flat maps have errors! But the Flat earthers deny there are errors.
If the earth would be flat and you would assume a globe you would end up with a completely distorted globe.
The ‘tape measurement’ system does not assume a globe.

If we started with Lat/Lon coordinates and inferred a distance from that, assuming a spherical surface, then that would be ‘assuming a globe’.

I don’t know if you are confused yourself, or whether you are trying to represent the arguments of a person who is deeply confused!

Offline edby

  • *
  • Posts: 1066
    • View Profile
Re: The Circularity Objection
« Reply #55 on: June 08, 2018, 11:57:43 AM »
But this objection is wrong [according to FE], you only get a nice globe, because your measurements were done on a globe.
But if it’s ‘because’ rather than ‘assuming that’, then FE position collapses.

[edit]Put it another way:

FE: You are wrong because you have assumed that the earth is a globe.
FE: You are wrong because the earth is a globe.

See the difference?
« Last Edit: June 08, 2018, 12:05:16 PM by edby »

Offline hexagon

  • *
  • Posts: 192
    • View Profile
Re: The Circularity Objection
« Reply #56 on: June 08, 2018, 12:34:32 PM »
Yes, if you directly project the measurements onto a model of the globe earth, then it will directly fit. But flat-earthers are right if they say, no one is carrying around globes for navigation, everyone uses flat maps.
But they would have to concede the flat maps have errors! But the Flat earthers deny there are errors.
If the earth would be flat and you would assume a globe you would end up with a completely distorted globe.
The ‘tape measurement’ system does not assume a globe.

If we started with Lat/Lon coordinates and inferred a distance from that, assuming a spherical surface, then that would be ‘assuming a globe’.

I don’t know if you are confused yourself, or whether you are trying to represent the arguments of a person who is deeply confused!

It assumes a globe earth in the moment you transfer your data on a map. 

It's easy to see. Let's assume two groups of surveyors are starting at the same point. And they do their triangulation measurements along two different directions. And the angle between the two directions is 60°. Now the proceed like this for 1000km. After that both change their directions by 60°. On a flat earth they would now meet after 500km under an angle of 0° degree. And all the points they measured would fit together to a nice triangle each side 1000km long, all angles 60°.

And on a globe?

They would first proceed along two great circles that intersect at the starting point under an angle of  60°. After 1000km they would change their direction again by 60° to approach each other. But are they now following the same great circle? No, at a distance unequal to 500km they would meet under an angle unequal to 0°, because they are following two different great circles. To meet in a straight line on the same great circle, they would have to turn by a bit more than 60°. But anyway, they would not meet after 500 km, because also the initial 60° angle was wrong.

You see, in the whole procedure of large scale mapping you have to take into account, what is the shape of the underlying surface. Only on small scales you can neglect it. 

Offline hexagon

  • *
  • Posts: 192
    • View Profile
Re: The Circularity Objection
« Reply #57 on: June 08, 2018, 12:53:09 PM »
But this objection is wrong [according to FE], you only get a nice globe, because your measurements were done on a globe.
But if it’s ‘because’ rather than ‘assuming that’, then FE position collapses.

[edit]Put it another way:

FE: You are wrong because you have assumed that the earth is a globe.
FE: You are wrong because the earth is a globe.

See the difference?

Yes, that's my point. The objection they have, is a pseudo argument.

if you're dealing with sphere, its not a problem to take this into account, it's a must. While on a flat-earth, it would be a must to take a plane into account.

The geometry you use, must be the one of the space you're dealing with.

Offline edby

  • *
  • Posts: 1066
    • View Profile
Re: The Circularity Objection
« Reply #58 on: June 08, 2018, 01:16:36 PM »
It assumes a globe earth in the moment you transfer your data on a map. 
I wonder if this is an English language problem. Do you mean that it implies a globe earth in the moment you transfer your data on a map?

English 'assumes' and 'implies' have radically different meanings.

Offline hexagon

  • *
  • Posts: 192
    • View Profile
Re: The Circularity Objection
« Reply #59 on: June 08, 2018, 02:18:39 PM »
It assumes a globe earth in the moment you transfer your data on a map. 
I wonder if this is an English language problem. Do you mean that it implies a globe earth in the moment you transfer your data on a map?

English 'assumes' and 'implies' have radically different meanings.

Possible, I'm not a native speaker...

I wanted to say, that it will not fit together to a nice map if just take your raw data and you try to draw a 2D map out of them. You have to do a projection like any cartographer has to do. You have to adjust the measured angles and/or distances.