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Offline Tumeni

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Re: Latitude and longitude - please enlighten me
« Reply #60 on: July 11, 2020, 12:19:01 PM »
For FE to be true, either (1) lines of longitude are not straight or (2) lines of longitude do not converge at the Poles.

Lines of lat or long are bisected by angles, the difference between such lines being expressed in degrees of angle.

By definition, this has no meaning on FE. Where would you draw the angle? Where do the lines or vectors forming the angle meet?
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Not Flat. Happy to prove this, if you ask me.
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Nearly all flat earthers agree the earth is not a globe.

Nearly?

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Offline GreatATuin

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Re: Latitude and longitude - please enlighten me
« Reply #61 on: July 11, 2020, 12:37:32 PM »
Take it as a thought experiment: for one moment, forget the geometrical definitions of latitude and longitude, just consider them as coordinates of a location on Earth.

The point is that we can determine latitude and longitude through observation of celestial objects and measurements of time. And conversely, knowing latitude and longitude allows us to know for example at what time the Sun rises and sets on a given date.

Of course, the mere fact that we can use angles as coordinates should tell us something about the shape of the Earth. But let's start with the basics, and let's see if someone denies the reality of the concept of latitude and longitude.
Nearly all flat earthers agree the earth is not a globe.

you guys just read what you want to read

Offline edby

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Re: Latitude and longitude - please enlighten me
« Reply #62 on: July 11, 2020, 04:11:27 PM »
My statements don't actually mention "straight lines",

I agree, I was just wondering if one could add a further statement that longitude lines are the shortest distance between two points, to see if that is a point of disagreement.

Offline iamcpc

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Re: Latitude and longitude - please enlighten me
« Reply #63 on: August 04, 2020, 06:39:46 PM »
I've read a number of posts where latitude and longitude are dismissed by FErs because they are based on a globe earth.

Robin,

I've researched this and I'm also confused about the claim because we have been able to navigate using the stars without using the words "Longitude" and "Latitude"




In terms of Latitude it does not appear to me to be based on a spherical coordinate system. It appears to be based on where you are, in relation to the North star. This was made clear to me when I learned about the Kamal.

https://en.wikipedia.org/wiki/Kamal_(navigation)


The video below discusses the Kamal around 2 minutes.



So is it only the longitude part of the system which is based on a spherical earth?



Re: Latitude and longitude - please enlighten me
« Reply #64 on: August 05, 2020, 08:49:20 AM »
I've read a number of posts where latitude and longitude are dismissed by FErs because they are based on a globe earth.

Robin,

I've researched this and I'm also confused about the claim because we have been able to navigate using the stars without using the words "Longitude" and "Latitude"




In terms of Latitude it does not appear to me to be based on a spherical coordinate system. It appears to be based on where you are, in relation to the North star. This was made clear to me when I learned about the Kamal.

https://en.wikipedia.org/wiki/Kamal_(navigation)


The video below discusses the Kamal around 2 minutes.



So is it only the longitude part of the system which is based on a spherical earth?

I agree, you don't need to be on a spherical earth for latitude to have a meaning and it's undoubtedly useful for navigation. I would really like to hear from a range of FErs whether they would accept this and if not, why not?

I'd go further and say I don't believe there is an issue with longitude either. In principle, finding your longitude is easy. Find the exact time when the sun was due south at Greenwich UK. Find the exact time when the sun is due south at your current location. Work out the time difference. If it's 1 hour, then you are 15° away from Greenwich. This can work on a flat earth just as well as a spherical one, it's simply making use of the fact that the sun appears to travel across the sky at 15° per hour, nothing more. The sun certainly does this, it's easily observed, so if the earth is flat, then it's doing this on a flat earth, so the method still works.

In practice it's not quite as simple as that because the 15° per hour is only an average, it does speed up and slow down a bit throughout the year, but there are known ways to correct for this (see equation of time https://en.wikipedia.org/wiki/Equation_of_time).

Very informative video by the way.

Offline iamcpc

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Re: Latitude and longitude - please enlighten me
« Reply #65 on: August 06, 2020, 07:14:30 PM »
I'd go further and say I don't believe there is an issue with longitude either. In principle, finding your longitude is easy. Find the exact time when the sun was due south at Greenwich UK. Find the exact time when the sun is due south at your current location. Work out the time difference. If it's 1 hour, then you are 15° away from Greenwich. This can work on a flat earth just as well as a spherical one, it's simply making use of the fact that the sun appears to travel across the sky at 15° per hour, nothing more. The sun certainly does this, it's easily observed, so if the earth is flat, then it's doing this on a flat earth, so the method still works.


The main issue that I have with longitude being shape agnostic is that it a lot more complicated to calculate and was not really done by ancient navigators when the FE concept was much more mainstream than it is now.  It's more modern. It's not something you can calculate with sometime as simple as some rope and a board. Claims that it is based on a spherical coordinate system, from my perspective, are much more challenging for me to understand or offer an alternate theory to.

With latitude it seems to me that there is strong evidence that a navigator who calculated latitude and thought the earth was flat would do so in a similar way to a navigator who thought the earth was round.

Re: Latitude and longitude - please enlighten me
« Reply #66 on: August 07, 2020, 12:20:04 PM »
I'd go further and say I don't believe there is an issue with longitude either. In principle, finding your longitude is easy. Find the exact time when the sun was due south at Greenwich UK. Find the exact time when the sun is due south at your current location. Work out the time difference. If it's 1 hour, then you are 15° away from Greenwich. This can work on a flat earth just as well as a spherical one, it's simply making use of the fact that the sun appears to travel across the sky at 15° per hour, nothing more. The sun certainly does this, it's easily observed, so if the earth is flat, then it's doing this on a flat earth, so the method still works.


The main issue that I have with longitude being shape agnostic is that it a lot more complicated to calculate and was not really done by ancient navigators when the FE concept was much more mainstream than it is now.  It's more modern. It's not something you can calculate with sometime as simple as some rope and a board. Claims that it is based on a spherical coordinate system, from my perspective, are much more challenging for me to understand or offer an alternate theory to.

With latitude it seems to me that there is strong evidence that a navigator who calculated latitude and thought the earth was flat would do so in a similar way to a navigator who thought the earth was round.

I agree that latitude is simpler and has been an integral part of navigation for much longer. Again it would be a good starting point to at least establish if latitude on its own is or isn't a contentious issue for FErs.

The central difficulty with longitude is that it's all about time and until the 18th C there wasn't a reliable way of keeping time accurately, by which time of course, a belief in a globe earth was pretty much universal. Having said that, unless time is somehow a concept which doesn't work on a flat earth, everything else about the method is observation of the heavens and observations are observations, the shape of the earth doesn't really affect the results.

Offline iamcpc

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Re: Latitude and longitude - please enlighten me
« Reply #67 on: August 07, 2020, 04:27:02 PM »
I agree that latitude is simpler and has been an integral part of navigation for much longer. Again it would be a good starting point to at least establish if latitude on its own is or isn't a contentious issue for FErs.

The central difficulty with longitude is that it's all about time and until the 18th C there wasn't a reliable way of keeping time accurately, by which time of course, a belief in a globe earth was pretty much universal. Having said that, unless time is somehow a concept which doesn't work on a flat earth, everything else about the method is observation of the heavens and observations are observations, the shape of the earth doesn't really affect the results.


The question I have is how can we determine if your position in relation to the north star is based on a flat earth and refraction or a globe earth and refraction to determine if the claims that it's based entirely on a globe earth are supported or refuted by the evidence. As of now I don't know.

Offline edby

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Re: Latitude and longitude - please enlighten me
« Reply #68 on: August 07, 2020, 09:19:27 PM »
The central difficulty with longitude is that it's all about time and until the 18th C there wasn't a reliable way of keeping time accurately, by which time of course, a belief in a globe earth was pretty much universal. Having said that, unless time is somehow a concept which doesn't work on a flat earth, everything else about the method is observation of the heavens and observations are observations, the shape of the earth doesn't really affect the results.
Conceptually longitude is simple. Find the point at which the sun is highest, then look up the time at Greenwich. These days, simple. 200 years ago, not simple.

Offline edby

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Re: Latitude and longitude - please enlighten me
« Reply #69 on: August 08, 2020, 01:00:48 PM »
The question I have is how can we determine if your position in relation to the north star is based on a flat earth and refraction or a globe earth and refraction to determine if the claims that it's based entirely on a globe earth are supported or refuted by the evidence. As of now I don't know.
The fact that the North star has a certain altitude is merely an observation. You measure it in angles. How would that tell you anything about the shape of the earth?

But add the fact that its angle changes by 1 degree for every 111km you travel towards it or away from it, may tell you something. Nothing is certain of course, but the very simplest theory to explain that observation is that the earth is (approximately) spherical. Doesn't mean that it is spherical, and absolutely nothing can prove it for certain. But that hypothesis is one very simple explanation.


Re: Latitude and longitude - please enlighten me
« Reply #70 on: August 10, 2020, 09:24:00 PM »
Quote
but the very simplest theory to explain that observation is that the earth is (approximately) spherical.

I agree.  And generally speaking since the simplest is also likely to be the most obvious, then best go with that as an explanation until someone comes up with something better (or more simple) wouldn't you say? 

Re: Latitude and longitude - please enlighten me
« Reply #71 on: August 12, 2020, 02:04:48 PM »
I agree that latitude is simpler and has been an integral part of navigation for much longer. Again it would be a good starting point to at least establish if latitude on its own is or isn't a contentious issue for FErs.

The central difficulty with longitude is that it's all about time and until the 18th C there wasn't a reliable way of keeping time accurately, by which time of course, a belief in a globe earth was pretty much universal. Having said that, unless time is somehow a concept which doesn't work on a flat earth, everything else about the method is observation of the heavens and observations are observations, the shape of the earth doesn't really affect the results.


The question I have is how can we determine if your position in relation to the north star is based on a flat earth and refraction or a globe earth and refraction to determine if the claims that it's based entirely on a globe earth are supported or refuted by the evidence. As of now I don't know.

I'm not sure if refraction is a significant factor for mid-latitudes because the north star will be quite high above the horizon (or however you are determining level). Near the equator, when polaris is very low, sure.

I don't really see how measuring the angular height of something could be connected to the shape of the earth. Clearly we can measure the angular height and almost by definition if we measure this height/angle from two different locations and find it to be the same, then we say these are at the same latitude. We know that ancient mariners used things like kamals and this enabled them to find their way back to the correct port when they needed to, so the system clearly works, whether the earth is flat or some other shape.

Offline iamcpc

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Re: Latitude and longitude - please enlighten me
« Reply #72 on: August 12, 2020, 03:25:43 PM »
The question I have is how can we determine if your position in relation to the north star is based on a flat earth and refraction or a globe earth and refraction to determine if the claims that it's based entirely on a globe earth are supported or refuted by the evidence. As of now I don't know.
The fact that the North star has a certain altitude is merely an observation. You measure it in angles. How would that tell you anything about the shape of the earth?


I tend to agree after seeing the videos about it but it's a common belief that latitude is based on the earth being a sphere instead of based on how far you are away from the north star. What test could we devise to  determine if this is true or not.


But add the fact that its angle changes by 1 degree for every 111km you travel towards it or away from it, may tell you something. Nothing is certain of course, but the very simplest theory to explain that observation is that the earth is (approximately) spherical. Doesn't mean that it is spherical, and absolutely nothing can prove it for certain. But that hypothesis is one very simple explanation.

couldn't that also mean that the earth is not a sphere with the light from the north star propagating outward in a circle?

Offline edby

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Re: Latitude and longitude - please enlighten me
« Reply #73 on: August 12, 2020, 03:34:20 PM »
The question I have is how can we determine if your position in relation to the north star is based on a flat earth and refraction or a globe earth and refraction to determine if the claims that it's based entirely on a globe earth are supported or refuted by the evidence. As of now I don't know.
The fact that the North star has a certain altitude is merely an observation. You measure it in angles. How would that tell you anything about the shape of the earth?


I tend to agree after seeing the videos about it but it's a common belief that latitude is based on the earth being a sphere instead of based on how far you are away from the north star. What test could we devise to  determine if this is true or not.
What test could we devise to determine whether the apparent angle of Polaris to the horizon is in fact the apparent angle of Polaris to the horizon? Question makes no sense. Latitude by definition is the angle we observe, whether correct or not.

Quote
But add the fact that its angle changes by 1 degree for every 111km you travel towards it or away from it, may tell you something. Nothing is certain of course, but the very simplest theory to explain that observation is that the earth is (approximately) spherical. Doesn't mean that it is spherical, and absolutely nothing can prove it for certain. But that hypothesis is one very simple explanation.

couldn't that also mean that the earth is not a sphere with the light from the north star propagating outward in a circle?
It could mean that. If you allow enough curvature of light, anything is possible.

Re: Latitude and longitude - please enlighten me
« Reply #74 on: August 12, 2020, 04:00:58 PM »
The question I have is how can we determine if your position in relation to the north star is based on a flat earth and refraction or a globe earth and refraction to determine if the claims that it's based entirely on a globe earth are supported or refuted by the evidence. As of now I don't know.
The fact that the North star has a certain altitude is merely an observation. You measure it in angles. How would that tell you anything about the shape of the earth?


I tend to agree after seeing the videos about it but it's a common belief that latitude is based on the earth being a sphere instead of based on how far you are away from the north star. What test could we devise to  determine if this is true or not.

I can stand at a certain point in my garden and measure the angular height of a tree at the other end of the garden. If I stand closer to the tree, the angle gets larger, further away and the angle gets smaller. What if anything I can deduce about the shape of the earth from this I really don't know and I don't know what additional test I could make to my tree measurement to determine the shape of the earth either.

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Offline JSS

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Re: Latitude and longitude - please enlighten me
« Reply #75 on: August 12, 2020, 05:43:15 PM »
The question I have is how can we determine if your position in relation to the north star is based on a flat earth and refraction or a globe earth and refraction to determine if the claims that it's based entirely on a globe earth are supported or refuted by the evidence. As of now I don't know.
The fact that the North star has a certain altitude is merely an observation. You measure it in angles. How would that tell you anything about the shape of the earth?


I tend to agree after seeing the videos about it but it's a common belief that latitude is based on the earth being a sphere instead of based on how far you are away from the north star. What test could we devise to  determine if this is true or not.

I can stand at a certain point in my garden and measure the angular height of a tree at the other end of the garden. If I stand closer to the tree, the angle gets larger, further away and the angle gets smaller. What if anything I can deduce about the shape of the earth from this I really don't know and I don't know what additional test I could make to my tree measurement to determine the shape of the earth either.

If the tree was 323 light-years tall, then you could determine the shape by plotting the angles easily enough, just like we do with the North Star.

For a normal sized tree, if you get far enough away from it then the angle is going to behave differently if you are on a plane or a sphere. It will get lower faster on a sphere and eventually vanish. On a flat plane the angle will change rapidly when close, but far away it will slow down until it hardly changes at all.

Either way, if you plot the angle and distance measurements, they are only going to fit one shape.

Re: Latitude and longitude - please enlighten me
« Reply #76 on: August 13, 2020, 08:47:34 AM »
The question I have is how can we determine if your position in relation to the north star is based on a flat earth and refraction or a globe earth and refraction to determine if the claims that it's based entirely on a globe earth are supported or refuted by the evidence. As of now I don't know.
The fact that the North star has a certain altitude is merely an observation. You measure it in angles. How would that tell you anything about the shape of the earth?


I tend to agree after seeing the videos about it but it's a common belief that latitude is based on the earth being a sphere instead of based on how far you are away from the north star. What test could we devise to  determine if this is true or not.

I can stand at a certain point in my garden and measure the angular height of a tree at the other end of the garden. If I stand closer to the tree, the angle gets larger, further away and the angle gets smaller. What if anything I can deduce about the shape of the earth from this I really don't know and I don't know what additional test I could make to my tree measurement to determine the shape of the earth either.

If the tree was 323 light-years tall, then you could determine the shape by plotting the angles easily enough, just like we do with the North Star.

For a normal sized tree, if you get far enough away from it then the angle is going to behave differently if you are on a plane or a sphere. It will get lower faster on a sphere and eventually vanish. On a flat plane the angle will change rapidly when close, but far away it will slow down until it hardly changes at all.

Either way, if you plot the angle and distance measurements, they are only going to fit one shape.

The tree is quite tall, it's a Scots pine. I'm trying to imagine it 323 light-years tall, that would be something to behold!

Just to take a step back here and explain the thinking behind my original post, I've been trying to separate measuring the angle from measuring distances, because the minute we introduce distance, we get into shape and then bendy light/refraction, general relativity, non-euclidean geometries, interactive scale maps and all that stuff which goes around and around and gets nowhere with no agreement at all. The discussions become polarised.

Since you can measure an angle and/or measure a span of time, without measuring any distances at all, I'm saying let's just do that. We end up with two angles, a latitude and a longitude. We know that these are useful for navigation on the earth, because they've been used for centuries (especially latitude which goes back much much further).

9th century Arab sailors were using a kamal to determine latitude for navigation even before compasses were available.

What I want to know from flat earthers then is why they think measuring latitude with a kamal back in the 9th century can be dismissed as irrelevant because it's based on a spherical earth. It isn't, it's just measuring an angle, why can't you measure an angle on a flat earth?

I'd have liked to include longitude as well, but because that's more complicated and wasn't reliably used until the 17th C, then I'm happy to leave that out of the discussion too.

Honestly I'm just trying to backtrack to find some common ground we can all agree on. Haven't really got anywhere so far though.

Offline iamcpc

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Re: Latitude and longitude - please enlighten me
« Reply #77 on: September 06, 2020, 05:49:43 PM »
9th century Arab sailors were using a kamal to determine latitude for navigation even before compasses were available.

What I want to know from flat earthers then is why they think measuring latitude with a kamal back in the 9th century can be dismissed as irrelevant because it's based on a spherical earth. It isn't, it's just measuring an angle, why can't you measure an angle on a flat earth?

I think it's more the modern longitude and latitude system which is considered based on a spherical earth vs ancient latitude only systems but i'm not sure. Once I saw the kamal video I was confused about what made the ancient latitude measurements were based on the spherical earth. Back then I was under the impression that most of the people thought the earth was flat.

Re: Latitude and longitude - please enlighten me
« Reply #78 on: September 10, 2020, 02:21:46 AM »
Why can we only balance eggs on their ends when it is a solstice? I need answers.

Re: Latitude and longitude - please enlighten me
« Reply #79 on: September 17, 2020, 01:50:17 AM »
Help, can any provide me with an answer to my friend who said " I left NY on a cruise ship and noticed as we sailed away the high rise buildings were disappearing gradually from the bottom and could only see the top floors. that proves the earth is round." I told him I would explain that the next time we meet. Would someone be kind enough to help. kind Regards, paul