[stevecanuck]

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.

[JSS]

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.

[stevecanuck]

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.

[JSS]

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.

[stevecanuck]

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.

[JSS]

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.

[stevecanuck]

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.

[Longtitube]

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.

[stevecanuck]

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.

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.

[scomato]

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.

[Tom Bishop]

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.

[stevecanuck]

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.

[SimonC]

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.

Just out of interest. I hear so much about the disappearing ship and its like the name of one of those magic tricks you used to see on TV. And I wondered  -is there or has there ever been a (hopefully) recent experiment to prove this theory? And  I mean an official one done under verified 'lab' conditions (not in the dead of night on a mysterious land lake) and where there is a perfect flat calm on the ocean/mass of water (not even a ripple)?

[Jonathan]

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.

[SimonC]

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.

Only if the earth was a globe yes. But it isn't and they don't. And anyone who thinks they have seen an object disappear below the horizon due to curvature is having a bad day at the office. And their optician will tell them the same.

[SimonC]

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.

If you visit Quora that's all REs talk about - curvature; especially of the ocean or of large flat areas. There's even pics of pylons and wind farms out at sea that they claim are curving but on close inspection its just an optical illusion. They even claim to see curvature from mountain tops and will not accept that you would need to be 100,000 feet up at a very minimum to have the slightest chance of seeing something remotely like curvature. Most of the time its a circle of the rim of the earth (like those seen allegedly out of thick glass plane windows with fish eye lenses). It could quite easily be the rim of a flat round earth...who knows. But seeing an almost 2D image of something - take the blue marble for example - that could be a disc as there's no depth to it. And all of this proves nothing. But curvature is the goto for most REs - they can se it in their sleep I guess. Oh and they see ships clearly disappearing over the horizon with their bare eyes. That's some going but that's what they say. Probably wind up merchants all the same.

[AATW]

Only if the earth was a globe yes. But it isn't and they don't. And anyone who thinks they have seen an object disappear below the horizon due to curvature is having a bad day at the office. And their optician will tell them the same.

It's not difficult to find images and timelapses of this happening:



And this video is good, observations of a building taken across a strait from different distances showing more and more of the building hidden. What is it hidden by?

[SimonC]

Only if the earth was a globe yes. But it isn't and they don't. And anyone who thinks they have seen an object disappear below the horizon due to curvature is having a bad day at the office. And their optician will tell them the same.

It's not difficult to find images and timelapses of this happening:



And this video is good, observations of a building taken across a strait from different distances showing more and more of the building hidden. What is it hidden by?

I presumed such as was the clarity of the image that we were going to see the boat in the first video 'disappear' over the horizon. What happened? That would have at least provided some evidence to go on. Or did it not disappear after all?

[AATW]

I presumed such as was the clarity of the image that we were going to see the boat in the first video 'disappear' over the horizon. What happened?

What happened is as the first ship was mostly sunken he started to follow another ship which was coming towards him.
This is that second ship when he first starts to follow it and right near the end of the video:



If that isn't "evidence to go on" then I don't know what is. Where's the rest of it in that first image? Obviously you are free to do your own tests and satisfy yourself that the ships do completely disappear when they go far enough. I'd suggest the difference between those two frames needs some explanation on a FE.

[Action80]

...where there is a perfect flat calm on the ocean/mass of water (not even a ripple)?

Could not possibly be done on any existing body of water in it's liquid form in nature.

There is quite a few of them performed with laser beams on frozen lakes.