Looking for curvature is a fool's errand.
« on: March 01, 2021, 09:07:18 PM »

Trying to disprove that the earth is flat by looking for curvature is a fool's errand, because a circular shape is not proof of sphericalness. Hold up a flat, round placemat, and you will see a circular outline. Hold up a basketball, and you will also see a circular outline. So, what is it that allows you to perceive that the basketball is a sphere but the placemat is not? Depth perception - but only up to a certain distance. For a basketball that is only a few feet away from you, your depth perception can see that the sides of the ball curve away from the center of it and away from your face. This allows your brain to interpret it as a sphere (It probably helps that your brain already knows this and is predisposed to interpreting it as such).

If you were on a raft in the middle of a perfectly calm ocean, and spun around to view all 360 degrees, it would all look exactly the same. It would be like being in the middle of a large hoop that arcs around you at a constant distance and then attaches back to itself after describing a perfect circle. There would be exactly zero appearance of curvature in the dimension that would prove sphericalness. You can't see the 3rd dimension you're looking for because you can't see past a horizon that is equidistant from you at all times.

Now, magically levitate and repeat the process. No matter how high you go, nothing changes in terms of not being able to see proof of sphericalness due to curvature. The horizon is farther away (the hoop is bigger), but that's all. Perhaps if you went high enough, the earth would take on relative basketball proportions and your depth perception would kick in.
 
To be able to see sphericalness, you would have to be able to see farther to the left and right than you can in the middle (you could only do this with a transparent globe). So, the irony is that the spherical nature of the earth is the very thing that prevents you from seeing the spherical nature of the earth.

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Offline JSS

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Re: Looking for curvature is a fool's errand.
« Reply #1 on: March 01, 2021, 10:18:46 PM »
If you were on a raft in the middle of a perfectly calm ocean, and spun around to view all 360 degrees, it would all look exactly the same. It would be like being in the middle of a large hoop that arcs around you at a constant distance and then attaches back to itself after describing a perfect circle. There would be exactly zero appearance of curvature in the dimension that would prove sphericalness. You can't see the 3rd dimension you're looking for because you can't see past a horizon that is equidistant from you at all times.

I hate to bring up the boring sinking ship effect, but that would show the difference between being on a flat plane or circle, and being on a globe.  It wouldn't sink on a flat Earth.

The other effect is altitude letting you see further.  On a flat Earth, climbing up and down the mast of a ship wouldn't cause other ships to sink hull first into the water, but would on a flat earth.

There are a large number of visual effects you get on a sphere that you would not on a disk, and those allow you to indeed see the difference.

Re: Looking for curvature is a fool's errand.
« Reply #2 on: March 01, 2021, 10:41:27 PM »
If you were on a raft in the middle of a perfectly calm ocean, and spun around to view all 360 degrees, it would all look exactly the same. It would be like being in the middle of a large hoop that arcs around you at a constant distance and then attaches back to itself after describing a perfect circle. There would be exactly zero appearance of curvature in the dimension that would prove sphericalness. You can't see the 3rd dimension you're looking for because you can't see past a horizon that is equidistant from you at all times.

I hate to bring up the boring sinking ship effect, but that would show the difference between being on a flat plane or circle, and being on a globe.  It wouldn't sink on a flat Earth.

The other effect is altitude letting you see further.  On a flat Earth, climbing up and down the mast of a ship wouldn't cause other ships to sink hull first into the water, but would on a flat earth.

There are a large number of visual effects you get on a sphere that you would not on a disk, and those allow you to indeed see the difference.

Correct. My point is that looking for curvature is one of the go-to methods, but it shouldn't be.

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Offline JSS

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Re: Looking for curvature is a fool's errand.
« Reply #3 on: March 01, 2021, 11:55:18 PM »
If you were on a raft in the middle of a perfectly calm ocean, and spun around to view all 360 degrees, it would all look exactly the same. It would be like being in the middle of a large hoop that arcs around you at a constant distance and then attaches back to itself after describing a perfect circle. There would be exactly zero appearance of curvature in the dimension that would prove sphericalness. You can't see the 3rd dimension you're looking for because you can't see past a horizon that is equidistant from you at all times.

I hate to bring up the boring sinking ship effect, but that would show the difference between being on a flat plane or circle, and being on a globe.  It wouldn't sink on a flat Earth.

The other effect is altitude letting you see further.  On a flat Earth, climbing up and down the mast of a ship wouldn't cause other ships to sink hull first into the water, but would on a flat earth.

There are a large number of visual effects you get on a sphere that you would not on a disk, and those allow you to indeed see the difference.

Correct. My point is that looking for curvature is one of the go-to methods, but it shouldn't be.

I'm not sure I know anyone who thinks standing at sea level and looking for curvature is a go-to method for showing the Earth is round.   

Looking for it at 30,000 feet, sure.  Or 400 miles up on the ISS, of course.  Or from a million miles out it's pretty clear.  I just don't see many people arguing you can see an actual curve from the ground, so I wouldn't call it a go-to method at all.

Re: Looking for curvature is a fool's errand.
« Reply #4 on: March 02, 2021, 12:02:38 AM »
If you were on a raft in the middle of a perfectly calm ocean, and spun around to view all 360 degrees, it would all look exactly the same. It would be like being in the middle of a large hoop that arcs around you at a constant distance and then attaches back to itself after describing a perfect circle. There would be exactly zero appearance of curvature in the dimension that would prove sphericalness. You can't see the 3rd dimension you're looking for because you can't see past a horizon that is equidistant from you at all times.

I hate to bring up the boring sinking ship effect, but that would show the difference between being on a flat plane or circle, and being on a globe.  It wouldn't sink on a flat Earth.

The other effect is altitude letting you see further.  On a flat Earth, climbing up and down the mast of a ship wouldn't cause other ships to sink hull first into the water, but would on a flat earth.

There are a large number of visual effects you get on a sphere that you would not on a disk, and those allow you to indeed see the difference.

Correct. My point is that looking for curvature is one of the go-to methods, but it shouldn't be.

I'm not sure I know anyone who thinks standing at sea level and looking for curvature is a go-to method for showing the Earth is round.   

Looking for it at 30,000 feet, sure.  Or 400 miles up on the ISS, of course.  Or from a million miles out it's pretty clear.  I just don't see many people arguing you can see an actual curve from the ground, so I wouldn't call it a go-to method at all.

I guess you didn't read my post carefully enough.

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Offline JSS

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Re: Looking for curvature is a fool's errand.
« Reply #5 on: March 02, 2021, 12:46:20 AM »
I guess you didn't read my post carefully enough.

I did.  From a high enough altitude you can certainly tell the difference between a disk and a sphere.  Disks don't cause things (boats, buildings, continents) to vanish below the horizon when you or they move.  Spheres do.

Re: Looking for curvature is a fool's errand.
« Reply #6 on: March 02, 2021, 01:15:46 AM »
I guess you didn't read my post carefully enough.

I did.  From a high enough altitude you can certainly tell the difference between a disk and a sphere.  Disks don't cause things (boats, buildings, continents) to vanish below the horizon when you or they move.  Spheres do.

Which is why I said, "if you went high enough, the earth would take on relative basketball proportions and your depth perception would kick in".

The boat and building thing is a given. This was meant to address those who think curvature alone prove sphericalness.

Re: Looking for curvature is a fool's errand.
« Reply #7 on: March 02, 2021, 01:32:32 PM »

The boat and building thing is a given. This was meant to address those who think curvature alone prove sphericalness.

Equally, standing at the water’s edge or sitting in a boat with a clear 360 degree horizon is no proof that the world is flat. I watched the sunlight striking the mountain tops 20 miles away and moving down to sea level over the course of 10 minutes after sunrise. That’s more of a pointer to curvature of the earth to my mind.
Once again - you assume that the centre of the video is the centre of the camera's frame. We know that this isn't the case.

Re: Looking for curvature is a fool's errand.
« Reply #8 on: March 02, 2021, 04:56:37 PM »

The boat and building thing is a given. This was meant to address those who think curvature alone prove sphericalness.

Equally, standing at the water’s edge or sitting in a boat with a clear 360 degree horizon is no proof that the world is flat.

Never said or hinted it was.
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I watched the sunlight striking the mountain tops 20 miles away and moving down to sea level over the course of 10 minutes after sunrise. That’s more of a pointer to curvature of the earth to my mind.

Ok. You didn't understand my post. I'm going to leave it there.

Offline scomato

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Re: Looking for curvature is a fool's errand.
« Reply #9 on: March 03, 2021, 08:27:22 PM »
When I travel to the other end of Lake Ontario and view my home city of Toronto from the city of St. Catharines, why does the CN Tower appear 2/3 as tall as it should?

If the Earth was flat the CN Tower should appear as-is. In the image below, you can see a Mirage Effect (eg. where the white roofed Rogers Center is smeared) but due to its gigantic height you can see how low the CN Tower dips below the horizon.



« Last Edit: March 03, 2021, 08:30:10 PM by scomato »

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Offline Tom Bishop

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Re: Looking for curvature is a fool's errand.
« Reply #10 on: March 03, 2021, 09:01:49 PM »
Your picture overlay suggests that the earth should obscure all the buildings to the left of the tower.

What you have provided is evidence that it's not actually the curvature of the earth that is doing this.

Re: Looking for curvature is a fool's errand.
« Reply #11 on: March 04, 2021, 12:23:42 AM »
When I travel to the other end of Lake Ontario and view my home city of Toronto from the city of St. Catharines, why does the CN Tower appear 2/3 as tall as it should?

If the Earth was flat the CN Tower should appear as-is. In the image below, you can see a Mirage Effect (eg. where the white roofed Rogers Center is smeared) but due to its gigantic height you can see how low the CN Tower dips below the horizon.



And you're another who didn't get my post.

You seem to think I'm offering a proof that the earth is flat.