[limprichard]

Would someone explain to me why on a Flat Earth the horizon will not be the edge of the flat earth. This is A FACT if the Earth is Flat. It will only be untrue if the Earth isn't Flat. Isnt that what the Flat Earth society believes?

[ElTrancy]

Would someone explain to me why on a Flat Earth the horizon will not be the edge of the flat earth. This is A FACT if the Earth is Flat. It will only be untrue if the Earth isn't Flat. Isnt that what the Flat Earth society believes?

Once again, bringing up a CN topic, didn't Junker literally just put this there?

[OrigamiBoy]

Here is whats on the wiki:

https://wiki.tfes.org/Horizon_always_at_Eye_Level

[jimbob]

Would someone explain to me why on a Flat Earth the horizon will not be the edge of the flat earth. This is A FACT if the Earth is Flat. It will only be untrue if the Earth isn't Flat. Isnt that what the Flat Earth society believes?

I went through this with my derived formula (see earlier), it is obvious the horizon will be at eye level if the earth is round. If on a flat disc then it will be at the edge of the earth but of course it isnt because the earth is round.

[inquisitive]

Would someone explain to me why on a Flat Earth the horizon will not be the edge of the flat earth. This is A FACT if the Earth is Flat. It will only be untrue if the Earth isn't Flat. Isnt that what the Flat Earth society believes?

I went through this with my derived formula (see earlier), it is obvious the horizon will be at eye level if the earth is round. If on a flat disc then it will be at the edge of the earth but of course it isnt because the earth is round.

What is your definition of eye level?

[jimbob]

Here is whats on the wiki:

https://wiki.tfes.org/Horizon_always_at_Eye_Level

Been through this, it isnt correct. The reason it is at eye level is because it isnt (not quite). However our height in relation to the distance to the horizon is small (a couple of meters in relation to many killometers hence the angle is nearly ninty (89.97 degrees)
Found from assuming a height of 2m which gives a horizon distance of 5.1km away.
This works with a spherical earth but with a flat one the horizon will be where the earth stops.

[jimbob]

Would someone explain to me why on a Flat Earth the horizon will not be the edge of the flat earth. This is A FACT if the Earth is Flat. It will only be untrue if the Earth isn't Flat. Isnt that what the Flat Earth society believes?

So it would seem that the argument about the horizon being at eye level proves round earth theory not flat earth theory if the earth was flat you would be right but you arent because it isnt.

[Bobby Shafto]

Flat Earth explanation for the horizon is different from that Globe Earth. You can't use one claimed mechanism to refute the other. (I suppose you can in a contest of rhetoric, but that gets nowhere if the sides can't agree on what manifests a horizon.)

Bottom line is Flat Earth claims horizon is always at eye level, which I understand to be 90 degs from perpendicular, parallel to earth surface. Height above surface won't change that angle. Globe Earth to the contrary says horizon will always be below eye level (vantage angle less than 90 degs from perpendicular). Just at low elevations it's difficult to detect due to size of globe. But with rise in elevation, a "dip" in horizon below eye level is observable.

You can argue forever and make no progress. But observing whether or not the horizon actually does always rise to eye level ought to resolve which explanation for a horizon is more sound.

[jimbob]

Flat Earth explanation for the horizon is different from that Globe Earth. You can't use one claimed mechanism to refute the other. (I suppose you can in a contest of rhetoric, but that gets nowhere if the sides can't agree on what manifests a horizon.)

Bottom line is Flat Earth claims horizon is always at eye level, which I understand to be 90 degs from perpendicular, parallel to earth surface. Height above surface won't change that angle. Globe Earth to the contrary says horizon will always be below eye level (vantage angle less than 90 degs from perpendicular). Just at low elevations it's difficult to detect due to size of globe. But with rise in elevation, a "dip" in horizon below eye level is observable.

You can argue forever and make no progress. But observing whether or not the horizon actually does always rise to eye level ought to resolve which explanation for a horizon is more sound.

If we assume a round earth with its accepted radius, here are some calculated angles for different heights (remember 90 degrees is eye level)
2m 89.95 degrees
10m 89.89 degrees
100m 89.67 degrees
1000m 88.98 degrees
10000m 86.79 degrees
So you see the horizon is always close to eye level even at 10 km height (only 3 degrees different at 10km above earth surface). It is difficult to detect a change of 3 degrees.

Now for a flat earth, the horizon would be at the edge of the world so you would need to know the diameter of the flat earth. Anyone care to estimate.

[Ballboy]

Surely if you look UP at the sun, it implies that if you were standing on the sun and looking at the “plate” if the earth were flat, you’d be looking down?!

Lol this whole “horizon rises to eye level” thing makes no sense whatsoever. I mean, what does it actually mean, and what would it actually prove even if it happened? If it did always rise to meet eye level, it’d have to physically actually MOVE as I ascended, OR the plate would actually be concave like a shallow pudding bowl! That’s not flat either.

The phenomenon of the horizon extending with observer elevation seems to point to the earth beinf some sort of ball, does it not?

[Bobby Shafto]

The phenomenon of the horizon extending with observer elevation seems to point to the earth beinf some sort of ball, does it not?

It does not. It’s “phenomenon” because we don’t have necks or eyeballs calibrated to detect the small angular drop in the horizon due to the size of the sphere. But if we can measure accurately and the phenomenon persists, it would not point to a ball earth. A ball earth should not present such a phenomenon when measured.

I can’t say I really understand how it would work on a flat earth, but I’ll take the flat earth claim that the horizon always stays level to the eye as truth, only because I know that should not be the case on a sphere. So it ought to at least be a discriminator between a surface that curves away from the observer and one that doesn’t.

[jimbob]

Surely if you look UP at the sun, it implies that if you were standing on the sun and looking at the “plate” if the earth were flat, you’d be looking down?!

Lol this whole “horizon rises to eye level” thing makes no sense whatsoever. I mean, what does it actually mean, and what would it actually prove even if it happened? If it did always rise to meet eye level, it’d have to physically actually MOVE as I ascended, OR the plate would actually be concave like a shallow pudding bowl! That’s not flat either.

The phenomenon of the horizon extending with observer elevation seems to point to the earth beinf some sort of ball, does it not?

Here is a sketch showing "eye level" and simple geometry to calculate viewing angle. Eye level would be 90 degrees. This relates to a sphere and an observation point above the sphere's surface, not necessarily the earth.
https://pasteboard.co/HkQHe0b.jpg
This is the simple formula by which I made the previous calculations.

[jimbob]

The phenomenon of the horizon extending with observer elevation seems to point to the earth beinf some sort of ball, does it not?

It does not. It’s “phenomenon” because we don’t have necks or eyeballs calibrated to detect the small angular drop in the horizon due to the size of the sphere. But if we can measure accurately and the phenomenon persists, it would not point to a ball earth. A ball earth should not present such a phenomenon when measured.

I can’t say I really understand how it would work on a flat earth, but I’ll take the flat earth claim that the horizon always stays level to the eye as truth, only because I know that should not be the case on a sphere. So it ought to at least be a discriminator between a surface that curves away from the observer and one that doesn’t.

The way it would work on a flat earth is that tan(angle)=(Distance from observer to edge of earth)/(Height of observer)
As you can see, the angle would greatley depend on how close the observer is to the edge of the earth and obviously the size of the flat earth. Since there are no estimates as to the diameter of the flat earth, calculation stops here im afraid.

[Bobby Shafto]

I can’t say I really understand how it would work on a flat earth, but I’ll take the flat earth claim that the horizon always stays level to the eye as truth, only because I know that should not be the case on a sphere. So it ought to at least be a discriminator between a surface that curves away from the observer and one that doesn’t.

The way it would work on a flat earth is that tan(angle)=(Distance from observer to edge of earth)/(Height of observer)
As you can see, the angle would greatley depend on how close the observer is to the edge of the earth and obviously the size of the flat earth. Since there are no estimates as to the diameter of the flat earth, calculation stops here im afraid.

That's not how Samuel Rowbotham explains it (or how his disciples understand it). The best I can make out is this conventional flat earth explanation is that the horizon is an apparent one; one of perception. It's not a geometric calculation of surface shapes and sight lines. Somehow, the ground plane rises and all planes above eye level descend, meeting at an apparent vanishing point/line, the distance of which is contingent on height above the ground plane, and resolution of the image receptor (eye, camera, telescope)...all merging in something called a convergence zone of atmospheric effects and obscurants. In other words, the horizon isn't an actual calculated line. It just is, and depends on the observer and anything that might be blocking.

I don't know. That's the best I can do. But I do know that trying to explain it geometrically isn't how the flat earth defense does it.

[jimbob]

I can’t say I really understand how it would work on a flat earth, but I’ll take the flat earth claim that the horizon always stays level to the eye as truth, only because I know that should not be the case on a sphere. So it ought to at least be a discriminator between a surface that curves away from the observer and one that doesn’t.

The way it would work on a flat earth is that tan(angle)=(Distance from observer to edge of earth)/(Height of observer)
As you can see, the angle would greatley depend on how close the observer is to the edge of the earth and obviously the size of the flat earth. Since there are no estimates as to the diameter of the flat earth, calculation stops here im afraid.

That's not how Samuel Rowbotham explains it (or how his disciples understand it). The best I can make out is this conventional flat earth explanation is that the horizon is an apparent one; one of perception. It's not a geometric calculation of surface shapes and sight lines. Somehow, the ground plane rises and all planes above eye level descend, meeting at an apparent vanishing point/line, the distance of which is contingent on height above the ground plane, and resolution of the image receptor (eye, camera, telescope)...all merging in something called a convergence zone of atmospheric effects and obscurants. In other words, the horizon isn't an actual calculated line. It just is, and depends on the observer and anything that might be blocking.

I don't know. That's the best I can do. But I do know that trying to explain it geometrically isn't how the flat earth defense does it.

Yes, had a look at Rowbothans theory, one primary problem is that he requires light rays to bend. Now this can happen at the boundary of two different types of material with a differing refractive index but the light ray leaving the horizon only passes through air so I think his theory needs to be revised. Because the light ray cant be bent sufficiently that means geometry can and should be used in calculation. The refractive index of air only varies between 2.5 - 2.85 at the earths most extreme temperatures. It is orders of magnitude too small with even the assumption of the most ridiculous temperature gradients.

Quote from 9 out of 10 doctors
jimbob is the best person on this site. No, seriously, jimbob is why I stay on this site.           I was going to say Tom is, but OK

[Bobby Shafto]

I'm not defending the rationale used in Earth Not a Globe.
But I'm also not going to critique it because that's proved to be fruitless.

Whatever explanation FE model wants to propose for it, sound or not, the bottom line is that it claims the horizon is always level from the vantage point of the observer. There's no rationalization for that in a globe model because a globe model refutes that claim. The horizon will dip below eye level with elevation.

So, the horizon reasoning is supplemental. Just measure it and see which it is. If the horizon dips, the surface is convex. If not, then the surface is flat.

[jimbob]

I'm not defending the rationale used in Earth Not a Globe.
But I'm also not going to critique it because that's proved to be fruitless.

Whatever explanation FE model wants to propose for it, sound or not, the bottom line is that it claims the horizon is always level from the vantage point of the observer. There's no rationalization for that in a globe model because a globe model refutes that claim. The horizon will dip below eye level with elevation.

So, the horizon reasoning is supplemental. Just measure it and see which it is. If the horizon dips, the surface is convex. If not, then the surface is flat.

I thought that we had established that the horizon dips for both a RE and FE model, its just the amount that differs. It would be impossible for it not too, unless the FE is infinitley long and I dont think the FE's are claiming that.

Quote from 9 out of 10 doctors
jimbob is the best person on this site. No, seriously, jimbob is why I stay on this site.           I was going to say Junker is, but OK

[Bobby Shafto]

I thought that we had established that the horizon dips for both a RE and FE model, its just the amount that differs. It would be impossible for it not too, unless the FE is infinatley long and I dont think the FE's are claiming that.

I don't think so. Any FE advocates want to agree that's been established?

I think not since a principle claim of FE is that the horizon never dips. It always rises to eye-level. I agree, I don't understand how that works, but I can't make the argument for them. I'm just accepting it on face value since, if true, it should be a distinguishing feature between flat and convex.

[jimbob]

I thought that we had established that the horizon dips for both a RE and FE model, its just the amount that differs. It would be impossible for it not too, unless the FE is infinatley long and I dont think the FE's are claiming that.

I don't think so. Any FE advocates want to agree that's been established?

I think not since a principle claim of FE is that the horizon never dips. It always rises to eye-level. I agree, I don't understand how that works, but I can't make the argument for them. I'm just accepting it on face value since, if true, it should be a distinguishing feature between flat and convex.

OK imagine standing on a flat earth, the horizon at eye level then going up 1 light year, how could the horizon still be at eye level now the flat earth is 1 light year below you. It is going to be straight down.

Quote from 9 out of 10 doctors
jimbob is the best person on this site. No, seriously, jimbob is why I stay on this site.           I was going to say Junker is, but OK

[Bobby Shafto]

OK imagine standing on a flat earth, the horizon at eye level then going up 1 light year, how could the horizon still be at eye level now the flat earth is 1 light year below you. It is going to be straight down.

I'm serious. You don't have to convince me. I get it. I'm not advocating for or defending the flat earth horizon explanation. If it proves that for elevations much less than 1 light year that the horizon DOES stay at eye-level and doesn't drop a fraction of a degree like I expect it to, then I'll give the flat earth horizon explanation a more serious look.

I imagine a flat earth advocate will say that you can't go up 1 light year from the flat earth.
How high could you go before being able to see the edge of a finite disc-shaped flat earth? From launching points in Tasmania, New Zealand or Cape Horn? Altitudes to see the edge (or the alleged ice wall)? Attainable, maybe? I leave that to a flat earth proponent. But just realize that for now, they give an explanation that combines perspective, ocular acuity and atmospheric effects/density for why there's a horizon at all and you can't see to 'the edge."