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Flat Earth?


gerrydandridge
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4 hours ago, Chinahand said:

So does anyone know why it is a trick question to ask what is the dependency between x and y on a sphere?

Maths4.thumb.png.b5ad9ab7928b8f141f3480afe9c7ab10.png

So why was it a trick question.  Because there is no dependency.  The distance you need to move to change the angle up to the sun by 1 degree is independent of how far you are away from the sub-solar point, O.

It is a constant, which is fixed simply by the size of the earth - if the earth's circumference is C, you have to move C/360 to get the angle up to the sun to change by 1 degree.

This means there is a radical difference between a flat earth and a spherical one in how angles up to the sun change as you move about the earth's surface:

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So ... we have set our scientific scene and gone through the first 3 stages of Rochester University's description of the scientific process.

We have two hypotheses which present very different ways that angles up to the sun will change as you move about the earth's surface.

So Paul.  What is stage 4?  What did Eratosthenes do, and in so doing inspired generations of other geographers, surveyors and astronomers in the centuries that followed?

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2 hours ago, quilp said:

Cosmological evangelism. All you need is faith...

https://www.theguardian.com/us-news/2018/nov/18/flat-earthers-keep-the-faith-at-denver-conference

And religion. 

That’s an interesting article Quilp. I suspect Gerrydandridge justifies his denial of evidence on religious grounds. He’s given hints about it now and then and is definitely no friend of evolution over millions of years. Not sure about PGW I think he’s more a curmudgeon than religious zealot but who knows. People believe lots of weird things. 

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54 minutes ago, Chinahand said:

That’s an interesting article Quilp. I suspect Gerrydandridge justifies his denial of evidence on religious grounds. He’s given hints about it now and then and is definitely no friend of evolution over millions of years. Not sure about PGW I think he’s more a curmudgeon than religious zealot but who knows. People believe lots of weird things. 

That's poppycock and you know it chinahand!

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So the final stage of Rochester Universities 4 stages of science is:

4. Performance of experimental tests of the predictions by several independent experimenters and properly performed experiments.

Now, Eratosthenes definitely did undertake an experimental test.  And in doing that test he was able to show that multiple hypotheses were incompatible with the evidence he had created, but as Wrighty (and I when we went through a similar exercise with Gerrydandridge) do admit Eratosthenes' results were insufficient in themselves to distinguish between a flat earth and a sphere.

Here is the data Eratosthenes collected marked on the graphs with Alexandria approx 924 km (5000 stadia) North of the tropic of Cancer and his result of 700 stadia per degree:

Maths6.thumb.png.dc75f14fa3fd8ac788094e6bd68fb7df.png

Now it is very easy to sneer and do people down, but this was in the 250s BC.  Eratosthenes was the first person to realise we could understand the size of our world by looking at how the angle up to the sun changes as we move over its surface.

It is using a rational explanation and evidence to make an argument - and the challenge is then for other scientists to repeat and vary the experiment and see how the evidence fits the different theories.

And this is where I find the Flat-Earthers so strange.  Science doesn't stop with Eratosthenes - as the Rochester University guide says multiple experiments and measurements are needed by multiple experimenter.

PGW - do you really think the collection of evidence stopped with Eratosthenes?

Also look at the graphs - look in the area greater than 6000 km from the sub-solar point O and where the distance to change the angle upto the sun by 1 degree (y) is less than 200 km.  Do you notice how the flat earth solid lines are all higher than this area?

It is an empirical, causal fact that once you are a certain distance from the sub-solar point no matter what the distance from the sun to the earth the distance you have to move to change the angle up to the sun by 1 degree will always be greater than say 200 miles.  Try to think why this might be.  

Look at the graphs - for low heights of the sun (say 2000km on my graph) the distance to be moved starts small, but then rapidly climbs steeply upwards.  For higher heights the distance to be moved starts high (look at the 12,000km line) and still gets higher, though at a slower rate - none of the lines for a flat earth can reach the point 6000, 100.

So what did later surveyors find?  One of my favourites is Jean Picard and his work inspired Cassini.

These surveyors were working far from the tropics in the mid latitudes where there is a huge difference between the way the sun would behave on a flat earth compared to a sphere.

PGW - willing to speculate what their results were? 

 

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You'll all have noticed I'm sure that after spending pages and pages calling out Chinahand over the scientific method, Paul has now shut up about it following the comprehensive demolition job China has done. I would hope that PGW will seek to post some of that info onto the Flat Earth debate LIVE!!!! pages in the future.

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