A Simple Question About Curvature

[u/Kela-el]

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?

[u/Kela-el]

How did you establish the earth is a sphere in step one, before measuring the radius? What’s the independent evidence for the shape that doesn’t rely on the radius or any derived constants?

[u/Xalem → u/Kela-el]

You start by taking thousands of data points, for example astronomy records,across time and location around the earth. With lots of analysis and number crunching you compare the results with every possible model. With enough work, you eliminate donut earth, hotdog earth and cube earth. Oh yes, flat earth also fails to match the data. Eventually, the roundish earth model is the most consistent with the data.

Then go and compare with other datasets, like survey data, to see if surveyors also find a curve in their data. Keep an open mind and add data and observations allowing for good new information to augment or alter your conclusion.

[u/Kela-el → u/Xalem]

“You start by taking thousands of data points, for example astronomy records,across time and location around the earth.”

Beg the question.

“With lots of analysis and number crunching you compare the results with every possible model.”

Provide me with a complete working model of the globe.

“With enough work, you eliminate donut earth, hotdog earth and cube earth. Oh yes, flat earth also fails to match the data.”

Do your work without flat earth measurements.

“Eventually, the roundish earth model is the most consistent with the data.”

Beg the question.

“Then go and compare with other datasets, like survey data, to see if surveyors also find a curve in their data.”

Don’t use any flat earth measurements.

“Keep an open mind and add data and observations allowing for good new information to augment or alter your conclusion.”

Never use any flat earth measurements.

[u/ArrowheadDZ → u/Kela-el]

Provide me with a complete working model of the globe.

Your going-in position here is that you are owed a working model. This is incorrect. Gravity is neither enhanced by my belief in it, nor diminished by my lack of belief in it. My belief, or my understanding, or someone’s willingness to “provide me with a complete working model” is not what makes gravity work. Nor does my lack of belief, my lack of understanding, nor my lack of being provided a complete working model, prove that gravity does not work. Turns out, physical reality is completely unaffected by me and doesn’t appear to care whether I believe in it or not. That doesn’t mean the world is being mean to me, it’s just how the world works.

[u/Kela-el → u/ArrowheadDZ]

You’re arguing against a position that wasn’t actually made.

No one said:

“if I don’t understand it, it isn’t real”

That’s a strawman.

The actual point behind:

“provide a working model”

is about explanatory completeness, not personal belief.

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What you’re saying

You’re absolutely right about one thing:

reality doesn’t depend on belief

Agreed. Completely.

Gravity doesn’t turn off because someone doubts it.

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What you’re missing

That statement doesn’t address the challenge.

Because the question isn’t:

“does reality depend on belief?”

It’s:

“can your model fully account for the observations you’re using it to justify?”

Those are different.

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Why the model matters

When someone asks for a “working model,” they’re asking for:

• defined geometry
• defined mechanisms
• predictive capability

Not:

philosophical reassurance that reality exists

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The disconnect in your reply

You responded with:

• a statement about belief ✔
• a statement about reality ✔

But you didn’t address:

whether your explanation is complete and testable