[edby]

Straight? Well in the round earth model lines of longitude are curved as they would be drawn on the surface of a sphere shaped object. By your logic the only possible map of the earth could be a flat earth map.

To be clear, by 'straight line' I mean the shortest distance between two points on the surface of the earth. I not talking about properties of a map, but rather the earth itself.

I claim that for any three points A B C on the surface of the earth which have the same longitude, i.e. where the sun is observed to be at its highest at the same time at each point, the shortest journey between A and C must pass through B.

As an example, the shortest possible route (presumably by air) between Southampton and Newcastle must pass through Leeds.

That's a simple claim and easy to verify. Do you agree, or shall we perform an experiment?

[edby]

A connected experiment. I am in a large flat desert where I make footprints on the sand. I head towards a high mast in the distance, i.e. I am careful to walk always in the direction of the mast. And assume there are no obstacles, so I can stick to that course.

After I reach the mast, there is a visible trail of footprints. Will the trail, seen from above, appear curved or straight?

Likewise, suppose A is somewhere in Chile, B is in Sydney. Both sail (or fly) towards the southern cross, being careful always to be heading in that direction. Will they be travelling in a straight, or a curved path? When I say 'straight', I mean a path that is the shortest possible distance across land or sea.

[iamcpc]

Straight? Well in the round earth model lines of longitude are curved as they would be drawn on the surface of a sphere shaped object. By your logic the only possible map of the earth could be a flat earth map.

To be clear, by 'straight line' I mean the shortest distance between two points on the surface of the earth. I not talking about properties of a map, but rather the earth itself.

I claim that for any three points A B C on the surface of the earth which have the same longitude, i.e. where the sun is observed to be at its highest at the same time at each point, the shortest journey between A and C must pass through B.

As an example, the shortest possible route (presumably by air) between Southampton and Newcastle must pass through Leeds.

That's a simple claim and easy to verify. Do you agree, or shall we perform an experiment?

I just did a simple experiment. Me and 2 of my friends went outside and stood in a triangle on the surface of the earth. About 3-4 feet from each other Points A, B and C.  Each of us observed the sun to be at its highest at the same time.

For each of us the shortest distance between the other did NOT pass through all three of us.

[edby]

I just did a simple experiment. Me and 2 of my friends went outside and stood in a triangle on the surface of the earth. About 3-4 feet from each other Points A, B and C.  Each of us observed the sun to be at its highest at the same time.
For each of us the shortest distance between the other did NOT pass through all three of us.

Not quite at the same time I am afraid. How did you detect the height of the sun?

[edby]

iamcpc, I believe you trust Google maps. Go to a place of your choice, right click and 'measure distance'. Select a place due North of it. Then place the cursor in the middle of the line created and pull to the left or right. See what happens to the distance, i.e. see whether there is a shorter distance between the two points.

You can do this anywhere. This suggests that lines of longitude are the shortest distance across the surface of the earth.

If you accept that, then it follows that the AE map is the only correct flat earth map.

[iamcpc]

iamcpc, I believe you trust Google maps. Go to a place of your choice, right click and 'measure distance'. Select a place due North of it. Then place the cursor in the middle of the line created and pull to the left or right. See what happens to the distance, i.e. see whether there is a shorter distance between the two points.

You can do this anywhere. This suggests that lines of longitude are the shortest distance across the surface of the earth.

If you accept that, then it follows that the AE map is the only correct flat earth map.

Well based on your criteria the following map is accurate:

http://suncalc.net/#/-0.0263,109.3425,3/2018.10.16/16:41

Others would claim that it's not accurate because the scale of the map changes based on the distance from the equator. So I provide a map in which the scale of the map does NOT change based on distance from the equator and you claim that the map is inaccurate because longitude lines are not straight.

Even though many of these maps with a changing scale are widely accepted by hundreds of thousands of people who use them they are not accepted by round earthers because it has a scale which changes based on distance to the equator.
https://search.yahoo.com/search/?p=maps

[edby]

So I provide a map in which the scale of the map does NOT change based on distance from the equator and you claim that the map is inaccurate because longitude lines are not straight.

If the longitude lines on the map are not straight then the map cannot be correct, because the longitude lines on the earth are straight. The map is representing a set of points as having one property, when in reality the same set of points has a quite different property.

[stack]

Doesn't necessarily address longitudinal lines, but this popped up today and thought it relevant to map making. Definitely gives a sense of what a rubik's cube a map really is; you shift to accommodate one aspect and it whacks out another.

[edby]

Here is the technique illustrated on Google maps.

Construct a triangle with the vertical side A on the same line of longitude. In this case, 55N:8E and 45N:8E. Then take any third point not on that line, to form two other sides B and C of the triangle. If you use the cursor to move that third point and move it around, you find the distance B+C always greater than the distance A, proving that (according to Google) a line of longitude is always the shortest distance between two points on the surface of the earth, i.e. are is straight.

You could object that Google isn’t calculating the distances correctly, but this argument is directed at those who believe that Google is calculating the distances correctly.

But if lines of longitude are straight then the AE map is the only possible map of Flat Earth. But that leads to the perverse consequence that the South Pole star is seen always to be in the same direction viewed from different points on the equator, yet the AE map says it is seen always in different directions from different points on the equator. This is a contradiction, ergo etc.

In summary, if Google maps correctly represents the geometry of the earth, then the earth is not flat. It’s logically impossible otherwise. But the earth is flat, therefore Google maps does not correctly represent the geometry of the earth.

[edby]

N.B. I see this argument already appeared in 2017.

Basically, ANY FE map that has straight meridians will have problems with where the Southern Cross star clusters are - and ANY FE map that has non-straight meridians will have problems with the compass agreeing with the direction to the pole star and/or the southern cross.

It's rather fundamental when you think about it.    If the N pole of your compass ALWAYS points to one point on the FE map (where the pole star is...with a bit of variance for the magnetic pole being offset) - and the S pole of your compass ALWAYS points towards another point on the FE map - then either your compass needle needs to bend quite a lot - or you can only EVER be on a straight line between those two places...at any other place - something has to break.