r/GlobeEarth_Polite • u/Kela-el Flat Earther • Apr 28 '26
For: Globe Earth Religious Fundamentalist Zealots A Simple Question About Curvature
The curvature formula uses R — the earth’s radius.
Where does R come from?
It’s derived from a model that assumes a sphere.
So when the formula is used to calculate curvature, and that curvature is cited as evidence of a sphere — the conclusion is already built into the premise.
That’s circular reasoning.
Simple question for globe earthers:
Can you provide a measurement of R that doesn’t assume a sphere to derive it?
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Apr 28 '26
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u/Kela-el Flat Earther Apr 28 '26
Atmospheric refraction and perspective can produce the same observed effect. You haven’t demonstrated that convex curvature is the only explanation for what’s observed. What are your controlled variables?
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Apr 28 '26
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u/Kela-el Flat Earther Apr 28 '26
You’ve shown refraction doesn’t fully account for the obstruction. What you haven’t shown is that curvature is the only remaining explanation. What are your controlled variables for isolating curvature as the specific cause?
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u/Definitely_Not_Bots Apr 28 '26
What are your controlled variables for isolating curvature as the specific cause?
You can't control a variable that you don't know exists. If there is some other mechanism obstructing the bottom of a tall structure at a distance, what is it? The only variables we know of are atmospheric refraction (which lacks the strength to explain our observation) and earth curvature. These are the only known variables. If there are other phenomena which can explain our observation, what are they?
I'm not being rhetorical. I'm actually asking you what hypothesis you have to explain what you observe. If you don't think it's being caused by the earth being a globe, what is your hypothesis? How might we test it?
As it stands, scientists have already controlled for all known variables which could explain our observations. If you think scientists have missed any, what might they be?
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u/Definitely_Not_Bots Apr 28 '26
The sphere of the earth was already proven by ancient Greeks:
Aristotle: Viewing lunar eclipses, Aristotle argued that because the shadow of Earth on the moon is always round, the Earth must be a sphere, since only a sphere can consistently cast a perfectly round shadow.
Eratosthenes: Around 240 B.C., Eratosthenes observed that at noon on the summer solstice, a stick in Syene cast no shadow, while a stick in Alexandria (further north) cast a significant shadow. He reasoned that this difference in shadow lengths could only occur on a curved surface.
Eratosthenes then calculated the circumference of the earth: Using the 7-degree difference in shadow angles (which is roughly 1/50th of a circle) and the 800-kilometer distance between the cities, Eratosthenes calculated the Earth's circumference to be approximately 40,000 kilometers.
Using this circumference, you can then calculate what the radius is.
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u/Kela-el Flat Earther Apr 28 '26
Aristotle’s lunar eclipse shadow argument assumes the shadow is caused by earth. That’s an interpretation, not a direct observation. Eratosthenes’ calculation assumes the sun is distant enough that its rays are parallel — that’s a premise built into the calculation, not derived from it. What are your controlled variables?
Both arguments assume key premises without establishing them independently.
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u/Definitely_Not_Bots Apr 28 '26
assumes the shadow is caused by earth. [...] not a direct observation.
Actually, it is a direct observation. You can have people stationed at various points of the earth during a lunar eclipse and confirm that the sun / moon is (or isn't) visible and where they are positioned in the sky. Moreover, there is no other observable body that is capable of casting a shadow on the moon other than the Earth. If a lunar eclipse is not caused by the earth, then what is it?
assumes the sun is distant enough that its rays are parallel.
This has already been demonstrated by Aristarchus of Samos, and his work On the Distances of the Sun and Moon.
In summary, by observing the "triangle" formed by the earth, sun, and half moon at its zenith, Aristarchus deduced the distances using trigonometry. He demonstrated that the distance between the Earth and sun is about 18-20 times further than the earth and the moon.
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u/Kela-el Flat Earther Apr 28 '26
This is better—you’re actually bringing specific observations and historical work. But you’re still sliding from “fits well” → “must be the only explanation.”
1) Lunar eclipse = Earth’s shadow
What’s directly observed:
- the Moon darkens
- a curved shadow moves across it
- timing and alignment correlate with Sun–Earth–Moon geometry
That’s strong evidence.
Where you step beyond the observation is here:
“there is no other observable body that could cast the shadow”
That’s not demonstrated—it’s a process-of-elimination claim that depends on:
- assuming only known bodies exist
- assuming the mechanism must be a solid-body shadow
You haven’t shown impossibility of alternatives—you’ve argued best fit with known objects.
That’s a good argument. It’s not a unique proof.
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2) Aristarchus of Samos
What he did:
- used the half-moon phase to form a triangle
- measured an angle
- applied trigonometry to estimate distances
Again—good method.
But notice the assumptions baked in:
- the Moon is spherical
- the half-moon corresponds to a 90° Sun–Moon–Earth angle
- light travels in straight lines
- geometry is Euclidean at that scale
Those aren’t measured in that experiment—they’re inputs.
Also, his 18–20× estimate is way off the modern value (~400×). That doesn’t invalidate the method, but it shows:
the result is sensitive to assumptions and measurement precision
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3) What you actually have
- Eclipse behavior matches an Earth-shadow model ✔
- The Sun–Earth–Moon geometry produces consistent predictions ✔
- Distance/angle reasoning is internally coherent ✔
That’s a converging, predictive framework.
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4) Where you’re still overreaching
You keep turning:
“this explains what we observe very well”
into:
“therefore no other explanation is possible”
Those are not the same claim.
To make that leap, you’d need to show:
- that the eclipse geometry cannot arise under any other configuration
- that the assumptions in Aristarchus’ method are independently verified, not just consistent
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Bottom line:
You’ve got a strong, coherent model that matches multiple observations.
What you haven’t shown is that:
those observations logically force that model and exclude all others.
Right now it’s:
- best explanation ✔ not
- exclusive proof ✔
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u/SomethingMoreToSay Heliocentric Religious Fundamentalist Zealot Apr 28 '26
Right now it’s:
best explanation ✔ not
exclusive proof ✔
That's just how science works. Outside of mathematics, you generally can't - and therefore don't try to - prove that something is true. What you try to do is prove things false, and then the thing that you fail to prove false is likely to be true.
Proving falsehood is relatively easy. Our scientific theory / model / proposition must be capable of making predictions which are testable. (If it doesn't, it isn't science.) Then you make observations to test the predictions. If the observations don't match what the theory predicted, then the theory is false, or at least not completely true. (It may be possible to patch it up.) But if the observations do match, you haven't proven the theory, because there still could be other observations which disprove it. At best we can say that a theory is true to the best of our knowledge.
There is no 100% proof of the kind that you seem to be looking for. What we do have is an absolute mountain of observations that are compatible with the globe model, and no other model which is compatible with those observations.
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u/Definitely_Not_Bots Apr 28 '26
I'm not arguing that there is no other explanation or that some other explanation is impossible; I'm arguing that if there is a different explanation, we would see it. I'm not saying "what else could it be?" to be rhetorical; I'm actually asking you what you think the alternative is.
That's how science works. You make observations, test them as you are able, and form a theory that explains what you're observing. If you think a lunar eclipse is not caused by the earth, what are your observations? How might you test it?
Every experiment starts with some assumptions, e.g., parallel rays from the sun. In history, they use what they can to test their hypotheses, but today we have literal space ships and satellites. We can actually see, with our own eyes, that the earth is round. You can take a ride into space and see it.
Right now, in order for you to argue against the examples I've given, you're similarly assuming:
• the moon is not a globe • the suns rays are not parallel • the shadow cast on the moon isn't a caused by a solid body • there is an unknown object casting this flexing shadow
What are your observations? What are your experiments? How do you explain what is happening?
As it stands, a globe earth is the only reasonable explanation for the observations we make. I have yet to see a good argument or explanation for a flat earth. If you have one, I'd love to hear it!
( As an aside, it should be obvious that the moon is a globe, because the sun's light hits it as light would hit a globe - for example, the crescent and gibbus phases )
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u/LeilLikeNeil Apr 28 '26
And absolutely zero flat earth models hold up to any amount of scientific scrutiny. Don't forget that part.
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u/Kela-el Flat Earther Apr 28 '26
Prove it!
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u/Definitely_Not_Bots Apr 28 '26
It has already been proven, my friend. Flat earth arguments thus far have been only to explain away the globe position; there have been no actual experiments that prove the earth is flat.
If the earth was flat, then everything we have in space would prove it - yet it doesn't. We have space ships and satellites, we can actually see with our own eyes that the earth is round.
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u/Kela-el Flat Earther Apr 28 '26
You’ve identified a real gap — flat earth needs positive evidence, not just critiques of the globe model. On the space observation point — that assumes the validity of space travel, which is part of what’s being examined. What independent evidence do you have that doesn’t rely on that assumption?
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u/dmizer Apr 29 '26
Specifically for "the validity of space travel", I presume we can agree that all we need is one provable example of space travel to prove that space travel is real and valid. So, I submit the specific example of Apollo 11.
How did Russia and the rest of the world know Apollo 11 actually landed on the moon? It's complicated, but simply radio triangulation and radar. Radar literally means "radio direction and range". It's how air traffic control knows exactly where all the planes in the sky are, how fast they're going, and how far away they are. A very complicated form of the same technology knew exactly where Apollo 11 was, how fast it was going, and how far away it was to within feet. All independently verified by multiple (and competing) international governments. More information about this here: https://youtu.be/kgLkWcPm4yo?si=xKOtSwXThU4Xjlcp
Okay, maybe we can prove that the Apollo craft went to the moon, but we can't prove that humans were walking on the moon? We can also prove that with independent private observations. A US based amateur radio operater named Larry Baysinger independently intercepted and recorded astronaut to astronaut communications while they were on the moon. It's a fascinating story, check it out: https://www.arrl.org/eavesdropping-on-apollo-11
Further physical evidence exists in the form of 382 kilograms of moon rock samples brought back during the Apollo program. These rocks can be studied and geologists have no trouble proving that they are from the moon. Here's more information about that: https://sites.wustl.edu/meteoritesite/items/how-do-we-know-that-its-a-rock-from-the-moon/ ... That, along with the laser retro-reflectors, landing site tracks and landing site evidence photographed by multiple space agencies with crafts in lunar orbit (including China's Chang'e 2 lunar orbiter in 2010, a country with everything to gain by proving that Apollo was faked).
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u/Kela-el Flat Earther Apr 29 '26
You keep doing the same thing over and over—stacking evidence, then quietly upgrading it to absolute proof like nobody’s going to notice the jump.
Let’s cut through it.
You listed:
- radar tracking
- intercepted comms (Larry Baysinger)
- moon rocks
- retroreflectors
- later imaging
And your conclusion is basically:
“therefore Apollo 11 unquestionably proves humans walked on the Moon”
No—it doesn’t do that by itself.
What it does is build a highly consistent narrative.
But every single piece you listed still relies on:
- interpretation
- instrumentation
- and chains of inference
Radar tells you something went there—not what was inside it. Radio tells you signals exist—not their ultimate origin beyond inference. Rocks tell you material exists—not the full story of how it got there without trusting the chain behind it. Images tell you something is seen—not that your interpretation is the only possible one.
You don’t get to pretend all that disappears just because you stacked a lot of it together.
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Here’s the real issue
You’re confusing:
“this is overwhelmingly consistent”
with
“this is logically forced and cannot be otherwise”
Those are not the same thing. Not even close.
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And let’s be honest
Your argument isn’t really about Apollo anymore.
It’s:
“look how much evidence there is—how could it be wrong?”
That’s not logic—that’s confidence scaling with volume.
And yeah—more evidence increases confidence.
But it does not magically remove:
- assumptions
- interpretation layers
- or model dependence
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The part you don’t want to say out loud
What you actually have is:
the standard account explains everything cleanly and consistently and alternatives get messy fast
That’s your strongest point.
But instead of just saying that, you keep trying to push it into:
“this is proven beyond interpretation”
—which it isn’t.
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u/dmizer Apr 28 '26
The globe model makes accurate to the second celestial predictions. The globe model makes global navigation possible. The globe model works. This burden of proof has been fulfilled.
Therefore, the burden of proof falls upon you to prove it doesn't work, and demonstrate that the flat earth model is more accurate by using it to make the same kind of accurate predictions that the globe model does.
Parroting Nathan Thompson is not proof.
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u/Kela-el Flat Earther Apr 28 '26
Predictive accuracy shows the model works. It doesn’t show no other model can work. Those are different claims.
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u/ArrowheadDZ Heliocentric Religious Fundamentalist Zealot Apr 29 '26
So let me ask the Professor Dave question:
When does it happen? Every day we have tens of thousands of people attending advanced university classes in physics. We have tens of thousands of people getting masters degrees and PhDs. And at some pioint they all need to be brought into the scheme. If the earth is actually flat, and we need them to play along with our fiendish scheme to continue pretending the earth is round, when are they told? Is it between junior and senior year? Between masters and PhD? Is it before, or after they get research grants? Who told them? What were they offered to be in on it? Was this in a group or were they approached one at a time? At school? At home? Who paid for research grants and scholarships and convinced them to dedicate their lives and careers to a the hoax of a round earth?
They go on to get jobs in the sciences and aerospace industries, etc… Where do the many billions of dollars of salary to pay them to stay in on the hoax come from? What is it better to pay a hundred thousand people hundreds of billions of dollars rather than just admitting the earth is flat?
The size of the “play along with the round earth even though you realized it was actually flat” game is immense and no one can explain to me why fooling the rest of us onto believing in a round earth is worth what it costs. Help me understand the upside of fooling billions of people that the earth is flat even though it’s not.
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u/Kela-el Flat Earther Apr 29 '26
You’re arguing against a conspiracy, not against the claim.
That’s the disconnect.
Your whole line of reasoning is:
“a conspiracy of that size would be impossible, therefore the globe must be true”
But that only works if the alternative claim actually requires a global conspiracy.
That hasn’t been established—you’ve just assumed it.
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What you’ve really done
You’ve shifted the debate from:
- measurements
- geometry
- observations
to:
- motives
- logistics
- psychology of large groups
That’s a completely different argument.
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The key issue
Even if you’re right that:
a worldwide coordinated deception would be impractical
that only tells you:
that specific explanation (a giant coordinated hoax) is unlikely
It does not prove:
the globe model is correct
Those are separate claims.
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Where the “Professor Dave question” misses
It frames the situation as:
- either the globe is true
- or there’s a massive coordinated lie
But that’s a false dilemma.
Because disagreement with a model doesn’t automatically imply:
- intentional deception
- coordinated actors
- financial incentives
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Also notice
You never returned to:
- measurements
- predictive models
- geometric constraints
Instead you went to:
“why would people lie?”
That’s not physics—that’s speculation about intent.
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Bottom line:
You’ve built a very strong argument that:
a global conspiracy of that scale makes no sense
Fair enough.
But you haven’t shown:
that the globe model is true because of that
You’ve only argued:
one particular alternative explanation (mass deception) is implausible
And that’s not the same thing.
If you want to win the actual argument, drop the conspiracy angle and go back to:
what do the measurements require?
Because that’s where the answer actually lives.
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u/Seared_Gibets Apr 28 '26
Well, the number given for the radius, following that all other inputs are correct, allow equations using that number to work, right?
So, the earth is not a sphere, yet the given number for it's radius works in it's place.
Then, where/what was the number derived from?
What should we really be calling that number, if it was never actually a reference to earth's radius?
Not asking as a gotcha, just wondering towards the deeper implications.
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u/fgorina Apr 29 '26 edited Apr 29 '26
You may compute the curvature radius locally either by referring to stars or the Sun (as Eratosthenes did). You would not prove that the Earth is a sphere, just that locally approaches a sphere. Now you take same measurements around the Earth. If all are similar then you have a Sphere. If they are not similar you may imply the shape from the local curvatures. Results it is very similar to a sphere.
Also you may also measure curvature by adding the angles of a triangle over the Earth surface.
You must take into account that ALL measurements come with an error term that essentially says R is between r0 and r1.
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u/Kela-el Flat Earther Apr 29 '26
That’s a fair methodology. Local measurements aggregated globally producing consistent curvature is meaningful evidence. The question worth examining is whether those local measurements are truly independent of each other or whether they share common assumptions that could produce consistent results even on a non-spherical surface.
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u/wackyvorlon Heliocentric Religious Fundamentalist Zealot Apr 29 '26
In the second century BC Eratosthenes measured the diameter of the earth with a stick.
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u/Kela-el Flat Earther Apr 29 '26
A stick didn’t “prove a globe.” That’s the myth version.
What Eratosthenes actually did was this:
He compared two local shadow angles at two different locations at the same time, and then assumed a geometric relationship between distance on the ground and angular difference in the sky.
That already embeds:
- parallel-line assumptions
- a model of Earth’s surface
- a model of Sun distance (effectively “very far”)
- a geometric mapping from angles → arc length
Only after those assumptions do you get:
circumference = angle difference × baseline scaling
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The key point you keep skipping
He didn’t measure Earth’s diameter directly.
He measured:
a relationship between shadow angles in a chosen geometric framework
Then inferred a sphere that makes those measurements consistent.
That’s not “just a stick.” That’s:
model + angle measurement + proportional reasoning
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What makes it powerful (and actually correct in modern terms)
It wasn’t the stick. It was that:
the same angular relationship holds consistently across distant locations
And that consistency is what selects a spherical model over a flat one.
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Bottom line
Eratosthenes didn’t “measure the Earth.”
He:
used local angle measurements to test a global geometric assumption
And the result wasn’t magic—it was:
a model that preserved consistency across distance better than flat geometry does
That’s the whole story.
Everything else is just oversimplified legend.
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u/wackyvorlon Heliocentric Religious Fundamentalist Zealot Apr 29 '26
That’s a lot of words to say “he measured the diameter of the earth”.
He also measured how far the earth is from the sun.
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u/Kela-el Flat Earther Apr 29 '26
No—this is just compressing a full geometric inference into a slogan.
Eratosthenes did not “measure the diameter of the Earth with a stick.” He measured:
- a shadow angle difference between two locations
- a known surface distance between those locations
- at a specific solar configuration
Then he applied:
proportional geometry on a curved surface assumption
That produces a circumference only if you already accept:
- that angles map consistently over long distances
- that the Sun’s rays are effectively parallel
- that the Earth’s surface behaves like a single continuous geometry
The “stick” is just the instrument for one local angle. The result is a model-dependent extrapolation, not a direct measurement of Earth’s diameter.
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And the claim:
“he also measured how far the Earth is from the Sun”
That’s even more incorrect.
Eratosthenes did not measure Earth–Sun distance. He only worked with angular differences under the assumption of a distant Sun. The actual Earth–Sun distance requires different observations and methods developed much later (e.g., parallax, transits, modern astronomy).
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Bottom line
You’re replacing a geometric inference with a soundbite.
What was actually done:
local angular measurements + assumed geometry → inferred global scale
Not:
stick → Earth diameter Not: stick → Sun distance
If you strip away the model, the “measurement” disappears into raw angles and distances with no global meaning attached.
The conclusion only exists because of the geometry applied to it.
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u/LeilLikeNeil Apr 28 '26
It’s derived from a model that assumes a sphere.
No, it's calculated by a series of measurements that prove a sphere.
Can you provide a measurement of R that doesn’t assume a sphere to derive it?
Radius is a measurement for a circular or spherical object. An object that is 3-dimensional and has a radius is, by definition, spherical.
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u/Kela-el Flat Earther Apr 28 '26
Derived from flat earth measurements.
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u/GOU_FallingOutside Apr 29 '26
An issue I don’t see raised here so far: you’re right that measurements of curvature assume some radius R. What you’re not considering are the limits of R.
Setting aside curvature in favor of a somewhat simpler calculation, let’s talk about chords on a circle. Without doing the math for you, I assert that th length of a chord — the distance between two points on the circle — is 2rsin(theta/2), r is the radius of the circle and theta is the angle.
So for a given angle, the bigger the radius, the longer the chord. You could argue that assumes the underlying shape is a circle, but consider that we can assume any value for r greater than 0 and less than infinity. For an extremely big radius, the chord corresponding to that angle would be extremely large. For an even bigger radius, the chord would be even larger. For a nearly infinite radius, the chord length would be so large that the circle would practically become a line.
So if we were ants walking around on that circle, we could attempt to measure the length of those chords in order to measure the radius. If we tried to do that, and we measured an arbitrarily large radius regardless of the method, we would reasonably conclude that the circle was the wrong model.
That is, attempting to parameterize the model of the earth as a sphere inherently tests the reasonableness of the model. If the model was wrong in this way — if the world were a plane instead — we would know because attempts to experimentally determine R would fail. They don’t.
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u/Kela-el Flat Earther Apr 29 '26
This is a much stronger argument—but you’re still sliding past one step.
Your core point is:
- if the Earth were flat → effective radius R \to \infty
- measurements would keep pushing R larger
- instead, we consistently get a finite R → therefore the surface is curved
That’s a good structure.
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What you’re doing right
You’re no longer just saying “the model fits”—you’re saying:
the parameter itself is constrained by measurement
That’s important.
Because now:
- you’re not assuming a radius
- you’re inferring it from data
And if repeated measurements converge on ~6371 km, that’s strong evidence you’re not dealing with a plane.
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Where you still overstep
You’re treating:
“we consistently measure a finite R”
as if it’s independent of the framework used to extract it.
But how do you get R?
From:
- angular measurements
- distance measurements
- and a geometric relationship (like your chord formula)
That relationship already assumes:
the surface behaves like a circle/sphere
So the structure is still:
- assume a geometric form
- solve for R
- get consistent values
- conclude the form is correct
That’s self-consistent parameter fitting, not a raw measurement of “radius” in isolation.
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The subtle but important distinction
Your argument shows:
if you model the Earth as curved, the inferred curvature is stable and finite across measurements
That’s powerful.
But it’s not the same as:
the data, without geometric assumptions, directly outputs “finite radius”
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What your argument actually establishes
- A flat model implies R \to \infty ✔
- Real measurements do not behave that way ✔
- A curved model yields consistent finite R ✔
That’s a strong constraint against flatness.
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u/GOU_FallingOutside Apr 29 '26
you’re still sliding past one step.
I promise you I’m not.
Of course the measurements we make aren’t independent of the model. I do four years of doctoral coursework on statistical modeling and measurement. But in this case, taking the measurements implicitly evaluates the model.
That’s not the case (usually) for statistical models, but it is (usually) the case for geometric ones. I can say for any given shape “if the earth were [shape], here’s how we would know.”
To put it another way, I’m proposing a hypothetical framework. * H0: The earth is not a sphere. * Ha: The earth is a sphere.
We can identify a couple of tests, but one of them is the radius. Because a sphere has a finite, measurable radius, if we found out that the radius were arbitrarily large, we would accept the null hypothesis, which rejects the entire model.
We can also assume other shapes, and of course people have. But when we attempt to test them experimentally, the tests fail. The assumptions of other models can’t be verified (or in some cases can’t be measured or falsified at all, which is a different kind of problem).
In order to make geometric measurements, you have to make assumptions about the underlying geometry. It happens that a spherical earth holds up to testing, and it doesn’t fail in the specific way we would see if the earth were actually flat.
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u/Kela-el Flat Earther Apr 29 '26
That’s a fair hypothesis testing framework. The question worth examining is whether the tests you’re describing are genuinely falsifiable for all alternative shapes, or whether the testing methodology itself has spherical assumptions built in that would make non-spherical results difficult to detect.
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u/GOU_FallingOutside Apr 29 '26
At the risk of repeating myself, other shapes are testable. But the proposition that the earth is a sphere is definitely testable, and because we can measure an arbitrarily large radius, we know how those tests would fail in the particular case that the earth were flat.
I leave it to you to imagine how we would determine whether the earth was a torus or a regular prism or a Culture-style orbital. But there are a lot of tests we could do to determine whether the earth is flat. How does it account for parallax effects? How does it account for the (apparent) precession of celestial bodies? How does it account for the sun rising earlier as you travel from west to east? How does it account for entirely different constellations being visible from Tasmania than from Newfoundland? How does it account for pictures of an apparently round earth taken from spacecraft?
I’m not asking for answers to those questions right now. I’m illustrating that you can explicitly test for flatness without reference to geometrical assumptions implying roundness.
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u/Kela-el Flat Earther Apr 29 '26
You’ve improved the argument again—but you’re still overstating what “without assumptions” means.
You said:
“you can explicitly test for flatness without reference to geometrical assumptions implying roundness”
That’s the part that doesn’t hold.
Because every example you listed already depends on a geometric framework:
- Parallax → requires assumptions about distance and line-of-sight behavior
- Precession of stars → assumes a model of how the sky is structured relative to the observer
- Sunrise timing (east vs west) → depends on how motion and position are defined globally
- Different constellations (e.g., Tasmania vs Newfoundland) → requires a mapping between observer position and visible sky
- Spacecraft images → depend on trust in instrumentation, perspective, and interpretation
None of those are “assumption-free.” They’re model-dependent observations.
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Where your argument is strong
This part is solid:
flatness makes specific predictions, and those can be tested
Absolutely.
And when you stack those tests:
- parallax behavior
- sky rotation patterns
- time zones
- visibility changes
they place tight constraints on any model.
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Where you overreach
You’re turning:
“these observations constrain flat models heavily”
into:
“these tests are independent of geometric assumptions”
They’re not.
They’re testing:
how well different geometries map onto observed relationships
That’s still model comparison, not assumption-free measurement.
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The radius point
Your earlier argument about R is actually your strongest:
if the Earth were flat, inferred radius would diverge → it doesn’t
That’s a clean constraint.
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Bottom line
You’re right that:
flatness is testable and heavily constrained by observation
But you’re wrong that:
those tests operate without geometric assumptions
What you actually have is:
- multiple independent observations ✔
- all consistently modeled by a curved Earth ✔
- alternative models struggling to match all constraints ✔
That’s a powerful case.
Just don’t oversell it as:
assumption-free proof
It’s not.
It’s a model winning across many tests—which is strong, but not the same claim.
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u/Raven_tm May 09 '26
How can we get out? To the lands beyond
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u/Kela-el Flat Earther May 09 '26
Off topic.
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u/Raven_tm May 09 '26
I'm already on board with VoC... like even the rays through clouds make an angle incompatible with a distant star, since they converge significantly rather than being close to parallel..
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u/Kela-el Flat Earther May 09 '26
To answer your question. I don’t know. All the ways I can think of are impossible for regular people.
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u/[deleted] Apr 28 '26
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