[TomInAustin]

The guy that did this video is very educated about physics.   This video is NOT presented to try and prove flat vs round but is a great explanation of the question.  Its also an entertaining one as it allows you to pan and tilt around.

https://www.youtube.com/watch?v=xpUcZXiKtfU

[Dr David Thork]

I'd recommend at least 2 grams of coke. 😵
Flat Earth humour is just on another plane.

Minimum settings 60,000 ft ... but 80,000+ ft recommended.

[Tumeni]

Simple geometry could tell us. Taking the Red Bull Space Dive of a few years ago as an example, climb to a certain height above the Earth's surface. Application of spherical geometry and trig, combined with the textbook figures for radius/diameter/circumference of Earth will tell you how far you will be able to see to the horizon, and what landmarks or geographical features you will be able to see within and at that distance.

The type of camera optics used does not enter into the discussion. Fisheye, telephoto - whatever, does not matter.

Apply this to the Red Bull flight, and it yields, at the stated height of the capsule, a visibility splay of approximately this size;



Note that no large body of water is expected to be seen with this splay, and none is seen in the video or photos from the capsule. Compare the video and photos to a map of the area within, and it can be seen that the capsule can "see" only the approximate area shown, and has no visibility beyond. Entirely consistent with a sphere/globe Earth. 

[jack44556677]

Thork beat me to it.

You have to be REALLY, REALLY high.  Like never coming down, never gonna be the same, kind of high.  LSD is the "space age" drug of choice, and one of the only ones strong enough to induce the kind of hallucination you are after.

There is no curvature of the horizon at any attainable height.  This has been confirmed to the nth degree, and you are welcome to confirm it for yourself for around $100 if you want.

The horizon is an optical illusion, the "edge" of nothing but our vision, and we were all egregiously mistaught about it.

[AATW]

There is no curvature of the horizon at any attainable height.  This has been confirmed to the nth degree

So are all the high altitude photos showing curvature fake or distorted?

The horizon is an optical illusion, the "edge" of nothing but our vision

If that is true why can we see things beyond the horizon but not all of them? Why do things sink below the horizon as they get further away. If it’s the limit of our vision shouldn’t they just vanish?
And why does horizon distance increase with height? Why does the limit of our vision increase when you ascend?
These things make sense in the context of a globe, what is your explanation?

[jack44556677]

So are all the high altitude photos showing curvature fake or distorted?

Yes.  They are all distorted, though "faked" is most often/likely not accurate.  There is no perfect lens, and no lens designed and calibrated to do what we are trying to.

If that is true why can we see things beyond the horizon but not all of them?

Because of diff/refraction, reflection, absorption/emission, and the omnipresent attenuation of light.  The farthest you can see, even aided, horizontally while standing anywhere on earth is around 200 miles.  Light doesn't travel forever.

Why do things sink below the horizon as they get further away.

They don't.  If you are careful with your observations you can observe that the receding object shrinks with the expected perspective, but the height of the ship never changes/lowers.  The illusion of the disappearance starts from the bottom up, and it has to do with the densest air interacting with the light nearest to the water and angular resolution.  The light from the bottom of the boat is the first that is unable to reach the distant observer (or be resolved) anymore.

f it’s the limit of our vision shouldn’t they just vanish?

There are more optical effects taking place.  They should "fade"/"haze" out, which they do - and the known density gradient means the fading out should happen by the bottom first typically.  Also the density gradient bends the light, so the light from the bottom of the boat is being diverted into the water. Reflection is possible, causing superior mirages occasionally, but that light is thrown over the observer at the shore.  This is all slightly tricky, so please let me know if I can clarify anything for you.

And why does horizon distance increase with height?

Because of the typical air density gradient (you are looking through a less dense/less interacting media), and the angular resolution limits of the eye caused by the receptor density, lens shape, and processing limitations of the eye/camera.  If there were 100 clones lined up perfectly in front of you (and cannot move but up and down), you might see only the first until you are lifted up higher. We can't see through/behind stuff is roughly the simple answer.

Good questions, though I have to assume you were merely interested in my perspective on it - as these are 101 flat earth questions and you don't seem to be new!

[Tumeni]

The horizon is an optical illusion, the "edge" of nothing but our vision, and we were all egregiously mistaught about it.

... but I/we can see things BEYOND the horizon. How could we do that, if it's at the limit of our vision?

[Pete Svarrior]

... but I/we can see things BEYOND the horizon. How could we do that, if it's at the limit of our vision?

You can see through the Earth? That's impressive. Have you considered monetising this ability?

[Iceman]

Many photographers have done just that - any time they sell a print of those city skyline pictures from across lakes on certain days. Making money off pictures of things beyond the horizon.

[Pete Svarrior]

Many photographers have done just that - any time they sell a print of those city skyline pictures from across lakes on certain days. Making money off pictures of things beyond the horizon.

In order to be "beyond" the horizon, they'd have to be on the same plane (or sphere) as the horizon. What you're talking about it objects which are above the horizon.

[AATW]

Many photographers have done just that - any time they sell a print of those city skyline pictures from across lakes on certain days. Making money off pictures of things beyond the horizon.

In order to be "beyond" the horizon, they'd have to be on the same plane (or sphere) as the horizon. What you're talking about it objects which are above the horizon.

Come on, dude.
You are playing silly semantic games here.
The original claim was that the horizon is the “edge of nothing but our vision”.
The implication is that we see a horizon because we can’t see any further.
If that were so then we wouldn’t be able to see anything beyond the horizon line. Here the word “beyond” clearly means “further away than”. I’m sure you understand that so why are you trying to wilfully misunderstand it to derail the discussion?

[Pete Svarrior]

The original claim was that the horizon is the “edge of nothing but our vision”.
The implication is that we see a horizon because we can’t see any further.

This is accurate.

Here the word “beyond” clearly means “further away than”.

This is not.

If you choose to misrepresent the guy's argument, his argument sure is going to souind silly; but do you think you'll have much luck convincing him of your views if you open your argument with such an obvious strawman?

[Tumeni]

What you're talking about it objects which are above the horizon.

No, that's not what is being talked about.

Beyond the horizon and still visible is both above the horizon and beyond it. Simple geometry.

[Pete Svarrior]

No, that's not what is being talked about.

I'm glad you agree - I was worried AATW may be correct, but now we know we no longer need to concern ourselves with objects above the horizon.

In that case, please detail your x-ray vision to us. I really think we may be on to something here - Tumeni, the man known for his honest assessment of the situation, is now claiming to be able to see through the surface of the Earth! Think about the military applications!

[Tumeni]

No, that's not what is being talked about.

I'm glad you agree - I was worried AATW may be correct, but now we know we no longer need to concern ourselves with objects above the horizon.

In that case, please detail your x-ray vision to us. I really think we may be on to something here - Tumeni, the man known for his honest assessment of the situation, is now claiming to be able to see through the surface of the Earth! Think about the military applications!

Everything the observer can see above the orange line is above the horizon from the observer's view point. This could include objects nearer than the physical horizon point, at that distance, or farther away.

Objects can be seen above this line which are physically further from the observer than the physical horizon point, and they are beyond the horizon.

Nothing to do with seeing through the Earth.

No?

This can include airborne objects, shipping, and tall buildings as well as celestial bodies like the Moon.

[Pete Svarrior]

No?

No.

Every point of the moon you will actually be able to see in this scenario will be located, at least by a miniscule amount, above the horizon. You agreed that these aren't objects we're discussing.

What you're talking about it objects which are above the horizon.

No, that's not what is being talked about.

So, please get back to demonstrating your x-ray vision to us.

[AATW]

Here the word “beyond” clearly means “further away than”.

This is not.

Well, it is. It's the way I'm using the word.

If you choose to misrepresent the guy's argument, his argument sure is going to souind silly; but do you think you'll have much luck convincing him of your views if you open your argument with such an obvious strawman?

I'm not deliberately misrepresenting his argument, I'm starting to think I don't understand it.
I've had a go at showing what I'm trying to say but I am pretty awful at drawing diagrams.



So you have a tall building on the right and two viewing points on the left. In the RE model the horizon is simply the edge of the earth. It's nothing to do with how far you can see although if the horizon is far enough away then that may become a factor and the horizon would not be a sharp line as it usually is at low altitudes.

So if you're at the viewing position on the right at a certain viewer height then the red line is drawn so it touches the earth - that's the horizon. Everything below that line beyond the horizon is occluded by the earth, hence the bottom of the building not being visible. Everything above that line is visible because you have clear line of sight to it.

If you're further away the the left viewing position and the same viewer height then the horizon will be the same distance from you - blue line - but because you're further away, and thus further round the globe, you can see less of the distant building.

The Turning Torso video demonstrates all this quite nicely. Obviously this is all massively out of scale, in real life you're only talking about 1 or 2 degrees in most cases round the earth so the leaning away of the building would not be noticeable.

If you're at the left viewing position but at a higher viewer height - green line - then the horizon is further away and you can see more of the building.

If the horizon was simply the "edge of nothing but our vision", then why would you see any of the building which is further away than the horizon? And this is where I fear I've not understood his argument. Maybe you or he could draw something to demonstrate.

[Tumeni]

Every point of the moon you will actually be able to see in this scenario will be located, at least by a miniscule amount, above the horizon. You agreed that these aren't objects we're discussing.

... and the Moon is physically beyond the horizon, being further away than it. Depending on its position, part or all of it, from the observer's viewpoint, will be above the horizon, but it will not physically be at the same distance as the horizon. 

So you agree that the observer can see things beyond the horizon, and that the horizon is not at a limit of vision.

No?

[Pete Svarrior]

... and the Moon is physically beyond the horizon, being further away than it.

You agreed that objects located above the horizon are "not what is being talked about". Have you changed your mind?

No?

No.

You have yet to demonstrate that you can see beyond the horizon, rather than being able to see farther in directions that don't lead towards the horizon, or under conditions different than looking at the horizon.

[Tumeni]

... and the Moon is physically beyond the horizon, being further away than it.

You agreed that objects located above the horizon are "not what is being talked about". Have you changed your mind?

OK, let's review;

At #6, I said, in response to jack;

The horizon is an optical illusion, the "edge" of nothing but our vision, and we were all egregiously mistaught about it.

... but I/we can see things BEYOND the horizon. How could we do that, if it's at the limit of our vision?

to which you replied;

... but I/we can see things BEYOND the horizon. How could we do that, if it's at the limit of our vision?

You can see through the Earth? That's impressive. Have you considered monetising this ability?

...and you then replied to iceman with

Many photographers have done just that - any time they sell a print of those city skyline pictures from across lakes on certain days. Making money off pictures of things beyond the horizon.

In order to be "beyond" the horizon, they'd have to be on the same plane (or sphere) as the horizon. What you're talking about it objects which are above the horizon.

At which point, you seemed to be referring to something being physically above the horizon, at the same distance as the horizon.

AATW pointed out "You are playing silly semantic games here."
You then disagreed that "beyond" means "further away than"...

My #12 was written on the basis of you referring to "above the horizon" as being at the same distance as the horizon.

So .... from there on, I drew a diagram to show the physical placement of objects which could be beyond the horizon,
at a distance farther than the horizon, but explicitly stated that from the viewpoint of the observer, they
were simply "above" the horizon in line of sight. 

I thought the diagram was clear, but ....

You have yet to demonstrate that you can see beyond the horizon, rather than being able to see farther in directions that don't lead towards the horizon, or under conditions different than looking at the horizon.

Semantics again. 

Analogy; If you stand in the spectator area, looking along the centre, lengthwise, of a football pitch, you can see the goalposts at the near end, and those at the far end. If you look at those at the near end, you can also have the far posts in your field of vision. If you look at the far posts, then  yes, you looking in "directions that don't lead to the near posts, or under conditions different than looking at the near posts", but you are still looking at a set of posts which are beyond the near ones, which are still in your field of view.

Look out at the horizon. You can look AT the horizon, whilst also seeing objects in your field of view above it, which are beyond it, and also at the lands and sea which are in your field of view below it, and which are nearer than it. See diagram above. If the diagram is unclear, then, as AATW says, perhaps you could draw something to show what you mean?