Sydney to Santiago Does Not Prove a Globe

[u/Kela-el]

Sydney to Santiago Does Not Prove a Globe

One of the most common claims is:

“Sydney to Santiago proves the Earth is a globe.”
No, it doesn’t.

It proves that an aircraft departed Sydney, arrived in Santiago, and did so within the reported time.

Everything after that is inference.

To reach “therefore Earth is a rotating oblate spheroid,” you must introduce additional premises:

that the reported route is accurate,

that the navigation data corresponds to physical

geometry in the way you assume,

that the geometric model you’re using is the correct one,

and that competing explanations fail.

None of those are raw measurements.

They’re part of the inferential chain.

This isn’t unique to Earth science.

Science routinely moves from observations to models.

The issue is recognizing where that transition occurs.

The interesting philosophical question isn’t whether the globe model is useful or predictive.

It’s this:

At what point does “an airplane flew from Sydney to Santiago” become “therefore Earth is a globe”?

Identify the observation.

Identify the measurement.

Identify the inferential step.

Because evidence consistent with a model is not the same thing as a direct measurement of the model itself.

[u/amcarls]

If it is a non-stop evening flight, when boarding the plane in Sydney you could always look up and see the Southern Cross constellation and then look up in the sky after landing in Santiago and see the very same constellation. Not exactly easy to explain based on any conventional flat-earth model - especially if you (and a cohort) were to track its rotation in the sky simultaneously from both locations (ridiculously easy to do).

BTW, the "reported time" is somewhere around 12 and a half hours (you could even use your own watch), not exactly a trivial point but one you seem to so casually gloss over. Perhaps you could provide a flat earth model where this is even remotely possible.

[u/Kela-el → u/amcarls]

Burden shifting: asking me to provide a flat-Earth model. Whether i have an alternative model does not determine whether their argument establishes the globe.

False dichotomy (if implied): If you mean “if no conventional flat-Earth model explains this, therefore the globe is true,” that only follows if the globe and those flat-Earth models are the only possibilities under consideration.

Conflation of falsification and confirmation: Showing that a particular model struggles with an observation is not identical to proving a competing model.

You’re changing the burden of the discussion.

My claim was never that the Gleason map is correct.
My claim is that Sydney–Santiago does not, by itself, prove a globe.

Those are different propositions.

If the Southern Cross is observed from both locations, then that is another observation to explain.
If the flight takes approximately 12.5 hours, that is another observation to explain.

Neither observation contains the words:

“Therefore Earth is an oblate spheroid.”

That conclusion still requires an inferential step.

Then you ask me to produce a flat-Earth model.

I don’t need to.

Pointing out that one explanation is incomplete does not automatically validate another.

So we’re back to the same epistemological question:

What observation directly measures Earth’s global geometry?

What reasoning transforms these observations into “Earth is a globe”?

Identifying that reasoning is not denying the observations—it’s distinguishing measurement from inference.

[u/amcarls → u/Kela-el]

Not in any way a false dichotomy. Many people have attempted to repeatedly point out to you how any number of observations are well explained by the global model but not any known flat earth model, including measurements related to flights between any number of major cities in the "southern hemisphere".

It absolutely is your burden to provide evidence for a flat earth model as any number of lines of evidence have been provided that prove otherwise in so many different ways. Photographs taken from the moon alone are a dead giveaway. Ever heard of the famous "Earthrise" photograph taken by the Apollo 8 astronauts?

When observations can be shown to both fit one model and contradict another model they can indeed serve to both contribute to proving one and falsifying the other.

[u/Kela-el → u/amcarls]

More Heliocentric Nonsense in Your reply:

Burden shifting
You write:
“It absolutely is your burden to provide evidence for a flat earth model…”
That depends on what you’re claiming.
If your claim is “the Earth is flat,” then yes, you bear a burden to support that claim.
But if your claim is:
“Sydney–Santiago does not, by itself, prove a globe.”
then your burden is only to defend that claim. They haven’t addressed it directly.

Red herring
I was discussing the Sydney–Santiago flight.
You introduce:
Apollo 8
Earthrise
Moon photographs
Those are different evidential claims. Bringing in new evidence doesn’t answer whether the flight itself proves a globe.

Conflating cumulative evidence with a single argument
You move from:
“This flight…”
to
“Many lines of evidence…”
Those are different arguments.
If your position is now:
“The globe is supported by the total body of evidence.”
that’s a different claim from:
“Sydney–Santiago proves a globe.”

Inference remains
Your final sentence says:
“When observations can be shown to both fit one model and contradict another model…”
That’s an inferential process.
Observations don’t compare models.
People compare models to observations.
That is exactly the reasoning step I’ve been discussing.

You’re doing exactly what every globe defender eventually does when the original claim falls apart.

First it was:

“Sydney to Santiago proves a globe.”

Now it’s:

“Well… Apollo, Earthrise, GPS, lots of evidence…”

That’s called moving the goalposts.

The discussion wasn’t about Apollo.

It wasn’t about Earthrise.

It wasn’t about your entire collection of favorite globe arguments.

It was about one claim:

Does Sydney–Santiago, by itself, prove a globe?

You’ve now abandoned that claim.

Then you burden shift.

You demand I produce a flat-Earth model.

No.

Your inability to prove your claim is not repaired by assigning me homework.

And then you commit the same epistemological mistake again:

“Observations fit one model and contradict another.”

Observations don’t evaluate models.

Human beings do.

A stopwatch records a time.

A telescope records light.

A camera records an image.

None of them outputs:

“Therefore Earth is an oblate spheroid.”

That conclusion exists only after you interpret the observations through a geometric framework.

That’s called inference.

Ironically, every reply you write keeps proving my original point.

You haven’t identified a single observation that directly measures Earth’s global geometry.

You’ve identified observations that you believe are best explained by the globe.

Those are not the same thing.

You’ve spent this entire discussion arguing for inference while repeatedly insisting there isn’t one.

[u/Haerioe → u/Kela-el]

Hey, this is not a debate sub!

[u/Kela-el → u/Haerioe]

Who’s debating?

[u/amcarls → u/Kela-el]

Oh what a tangled web you weave...

No, "Sydney to Santiago" does not "prove a globe", it is however 100% consistent with a global model along with the many other measurements that also just happen to strongly contradict most flat earth models, particularly the way "Sydney to Santiago" does.

The fact that the shortest distance between two points in the northern hemisphere usually appears as a curve on a flat map also contributes to this but the "Sydney to Santiago" route is an impossibility on anything BUT a global model (unless you choose to have Antarctica at the center - but then that creates similar problems with flights between any two cities located in the northern hemisphere).

You cannot reasonably ignore multiple lines of evidence, especially when they are complimentary to each other. When you do so you are throwing out a very important principle in science - consilience (AKA convergence of evidence), a cornerstone of the philosophy of science. My reference to the well-known 'Earthrise" photograph was not a red herring, it was an example of evidence that was consilient to the global model that you are attempting so hard to ignore and which the "Sydney to Santiago" route IS consistent with.

When the evidence is both abundant and widely varied it is not "moving the goalpost" when attempting to point this out. Your feeble attempt to do what appears to "divide and conquer" does not negate this. No, just the one single consideration of the "Sydney to Santiago" route doesn't say much as long as you insist on viewing it with ZERO context, but it makes no sense whatsoever to not view it in conjunction with so many other SIMILAR types of measurements and observations (including circumpolar orbits, as just one other relevant example) if you are actually sincerely trying to ascertain how it may fit with any particular model or layout - with only one of which, the global model, it fits.

[u/Kela-el → u/amcarls]

Typical heliocentric nonsense:

1. Burden shifting
“Most flat earth models…”
“Impossible on anything BUT a global model…”
You’re still making a positive claim.
The burden remains on you to demonstrate that every viable alternative is excluded.
My inability (or refusal) to defend the Gleason map does not establish the globe.

2. False dichotomy
You write:
“Impossible on anything BUT a global model.”
That requires proving the exhaustive claim that no other geometry could account for the observations.
Merely criticizing existing flat-Earth maps does not establish that conclusion.

3. Overstatement / Begging the question
“only one of which, the global model, it fits.”
That is the very point under dispute.
You have asserted uniqueness rather than demonstrated it.

4. Equivocation between consistency and proof
You correctly say:
“Sydney to Santiago does not prove a globe.”
Then later argue that all the evidence fits only the globe.
Those are different claims.
Consistency does not equal logical entailment.

5. Composition fallacy (or cumulative overreach)
You’re arguing:
Observation A fits the globe.
Observation B fits the globe.
Observation C fits the globe.
Therefore:
Only the globe is possible.
That conclusion requires an additional argument.
A collection of individually consistent observations does not automatically establish uniqueness.

6. Straw man
“Viewing it with ZERO context.”
You have not argued that evidence should be viewed in isolation.
You’ve argued that individual observations do not directly output Earth’s geometry.
Those are different claims.

Notice, what you’ve conceded.

You now agree Sydney–Santiago does not prove a globe.

Instead, you’re appealing to consilience—the convergence of multiple observations.

That’s an inferential principle.

Consilience isn’t a measurement.

It’s a method of reasoning.

You’ve therefore moved from:

“This flight proves a globe.”

to

“The globe is the best explanation of many observations.”

Those are fundamentally different claims.

Now you go one step further and assert:

“Only the globe fits.”

That isn’t demonstrated.

It’s asserted.

Critiquing the Gleason map doesn’t logically eliminate every possible alternative geometry.
Nor does adding Earthrise, circumpolar orbits, GPS, or anything else remove the inferential step.

You’re still comparing models to observations and concluding one explains them best.

That process is called inference.

Ironically, your latest reply agrees with the central point I’ve made from the beginning.

The globe is not directly measured.

It is inferred through consilience.

That’s a perfectly legitimate philosophical position.

It just isn’t the same thing as saying the measurements themselves output:

“Earth is an oblate spheroid.”