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Offline WellRoundedIndividual

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Eratosthenes Experiment Duplicated
« on: March 21, 2019, 04:50:14 PM »
https://www.researchgate.net/publication/272755423_Modern_replication_of_Eratosthenes'_measurement_of_the_circumference_of_Earth

Found this interesting little duplication of Eratosthenes experiment.  It was done with a 3rd city. 

Would anyone like to critique this or debunk it?

Here is another website with schools that have uploaded their measurements. A map shows plenty of schools on the same longitude, and therefore we could take that data and compare doing geometry the predicted angles for FE vs RE.

https://eratosthenes.ea.gr/
« Last Edit: March 21, 2019, 05:05:29 PM by WellRoundedIndividual »
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Offline markjo

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Re: Eratosthenes Experiment Duplicated
« Reply #1 on: March 21, 2019, 07:11:55 PM »
FE'ers will rightly point out that the Eratosthenes experiment, in and of itself, doesn't really prove that the earth is round because it assumes that the earth is round as part of its premise (calculating the diameter).  If one assumes that the earth is flat and the sun is near, then one can obtain similar results.

https://wiki.tfes.org/Erathostenes_on_Diameter
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Offline WellRoundedIndividual

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Re: Eratosthenes Experiment Duplicated
« Reply #2 on: March 21, 2019, 07:19:19 PM »
That only holds true geometrically if you only use two points. Once, you introduce a 3rd point or more, FE can no longer correctly predict the length of the shadow (or angle).
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Re: Eratosthenes Experiment Duplicated
« Reply #3 on: March 21, 2019, 09:12:21 PM »
My understanding of Eratosthenes experiment is that he was aiming to calculate the circumference of the Earth, not the diameter. Considering how long ago he lived I would say he did a pretty good job.

FE Wiki states...

Quote
It's a common misconception that Eratosthenes was measuring the circumference of the round earth in his shadow experiment. Eratosthenes had simply assumed that the earth was a sphere in his experiment, based on the work of Aristotle. He was actually measuring the diameter of the flat earth (distance across), which is a figure identical to the circumference of the round earth (distance around).

If that is true then why is it that the only reference I can find to this claim comes from websites relating to Flat Earth believers? I have checked many other sources which all state that Eratosthenes was assuming that the Earth was a perfect sphere.  It was common in ancient times for philosophers, scientists, theologists etc to believe that the Sun, Moon and Earth were perfect spheres and that the Earth was at the centre of the Universe.  The sphere was seen as the most perfect of the solids and so it natural to believe that the Earth was a sphere. Close but not quite right.

Eratosthenes realised the Sun was very distant so he also made the assumption that the Suns rays are parallel. So why should the notion that he was measuring a flat surface have entered his mind at any stage?   For his experiment to work the way it did if the Earth was flat, Eratosthenes would have had to have been measuring around the edge of the Earth. And that, as the FES states, is somewhere that no one has ever been. It is of course easy to create ones own interpretation of an experiment to suit ones own beliefs.
« Last Edit: March 22, 2019, 02:46:29 PM by manicminer »

Re: Eratosthenes Experiment Duplicated
« Reply #4 on: March 24, 2019, 01:35:11 AM »
That only holds true geometrically if you only use two points. Once, you introduce a 3rd point or more, FE can no longer correctly predict the length of the shadow (or angle).

I made a diagram of this so that everyone could understand this critical point. I chose three locations along the same longitude: Washington DC, Cayo Redondo in Cuba and Lima in Peru (actually the suburb Surquillo because it lined up the best). These are the assumed elevations at the same minute in all three locations (solar noon):

https://www.suncalc.org/#/38.8938,-77.0146,12/2019.03.23/13:15/1/3
https://www.suncalc.org/#/20.2974,-77.0192,16/2019.03.23/13:15/1/3
https://www.suncalc.org/#/-12.1144,-77.012,16/2019.03.23/12:15/1/3

The distances between the locations are 2061.424km for Washington to Cayo Redondo and 3585.03km for Cayo Redondo to Surquillo.

When FE technology gets advanced enough to verify the distances between these locations (there's not too much water so shouldn't be that hard), they'll find that the elevation of the sun measured at all three places points to two different locations in the sky. And the difference is immediately obvious. The reason is because the Earth is not flat.

Here's the diagram so you can check (1 pixel equals one kilometre):


« Last Edit: March 24, 2019, 01:37:10 AM by Balls Dingo »

Re: Eratosthenes Experiment Duplicated
« Reply #5 on: March 24, 2019, 10:17:47 PM »


When FE technology gets advanced enough to verify the distances between these locations (there's not too much water so shouldn't be that hard), they'll find that the elevation of the sun measured at all three places points to two different locations in the sky. And the difference is immediately obvious. The reason is because the Earth is not flat.

In other words your argument is a circular one that requires the assumption that the RE map is correct which is precisely what is at question.

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Offline markjo

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Re: Eratosthenes Experiment Duplicated
« Reply #6 on: March 24, 2019, 11:14:37 PM »
When FE technology gets advanced enough to verify the distances between these locations (there's not too much water so shouldn't be that hard), they'll find that the elevation of the sun measured at all three places points to two different locations in the sky. And the difference is immediately obvious. The reason is because the Earth is not flat.
In other words your argument is a circular one that requires the assumption that the RE map is correct which is precisely what is at question.
One would think that the fact that the RE map is used everyday in the international transportation and shipping industries would be compelling evidence that the RE map in question is, at least, somewhat correct.
Abandon hope all ye who press enter here.

Science is what happens when preconception meets verification.

If you can't demonstrate it, then you shouldn't believe it.

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Offline Tom Bishop

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Re: Eratosthenes Experiment Duplicated
« Reply #7 on: March 25, 2019, 12:43:04 AM »
When FE technology gets advanced enough to verify the distances between these locations (there's not too much water so shouldn't be that hard), they'll find that the elevation of the sun measured at all three places points to two different locations in the sky. And the difference is immediately obvious. The reason is because the Earth is not flat.
In other words your argument is a circular one that requires the assumption that the RE map is correct which is precisely what is at question.
One would think that the fact that the RE map is used everyday in the international transportation and shipping industries would be compelling evidence that the RE map in question is, at least, somewhat correct.

You would be incorrect.

https://gis.utah.gov/nad83-and-webmercator-projections/

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Offline markjo

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Re: Eratosthenes Experiment Duplicated
« Reply #8 on: March 25, 2019, 12:52:46 AM »
When FE technology gets advanced enough to verify the distances between these locations (there's not too much water so shouldn't be that hard), they'll find that the elevation of the sun measured at all three places points to two different locations in the sky. And the difference is immediately obvious. The reason is because the Earth is not flat.
In other words your argument is a circular one that requires the assumption that the RE map is correct which is precisely what is at question.
One would think that the fact that the RE map is used everyday in the international transportation and shipping industries would be compelling evidence that the RE map in question is, at least, somewhat correct.

You would be incorrect.

https://gis.utah.gov/nad83-and-webmercator-projections/
Would you care to explain the relevance of your link to my post?
Abandon hope all ye who press enter here.

Science is what happens when preconception meets verification.

If you can't demonstrate it, then you shouldn't believe it.

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Offline Tom Bishop

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Re: Eratosthenes Experiment Duplicated
« Reply #9 on: March 25, 2019, 12:55:36 AM »
When FE technology gets advanced enough to verify the distances between these locations (there's not too much water so shouldn't be that hard), they'll find that the elevation of the sun measured at all three places points to two different locations in the sky. And the difference is immediately obvious. The reason is because the Earth is not flat.
In other words your argument is a circular one that requires the assumption that the RE map is correct which is precisely what is at question.
One would think that the fact that the RE map is used everyday in the international transportation and shipping industries would be compelling evidence that the RE map in question is, at least, somewhat correct.

You would be incorrect.

https://gis.utah.gov/nad83-and-webmercator-projections/
Would you care to explain the relevance of your link to my post?

The summary is in the title:

Quote
The Earth is Not Round! Utah, NAD83 and WebMercator Projections

The maps are based on flat earth maps, not round earth maps. Otherwise the title would more accurately  be "The Earth is Round!"
« Last Edit: March 25, 2019, 12:57:45 AM by Tom Bishop »

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Offline markjo

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Re: Eratosthenes Experiment Duplicated
« Reply #10 on: March 25, 2019, 01:08:29 AM »
One would think that the fact that the RE map is used everyday in the international transportation and shipping industries would be compelling evidence that the RE map in question is, at least, somewhat correct.

You would be incorrect.

https://gis.utah.gov/nad83-and-webmercator-projections/
Would you care to explain the relevance of your link to my post?

The summary is in the title:

Quote
The Earth is Not Round! Utah, NAD83 and WebMercator Projections
I don't think that means what you think it means.
Geographic coordinates use latitude and longitude values to define positions on the 3D surface of the earth, which is of course, best modeled as an ellipsoid, not a sphere. The ellipsoid and its accompanying anchor point that ties it in to the real world, are known collectively as the WGS84 datum. The WGS84 datum is what the constellations of GPS satellites use natively.


The maps are based on flat earth maps, not round earth maps. Otherwise the title would more accurately  be "The Earth is Round!"
Interesting.  I thought the article was describing the ramifications of dealing with 3 different coordinate systems describing an ellipsoidal earth.
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Offline Tom Bishop

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Re: Eratosthenes Experiment Duplicated
« Reply #11 on: March 25, 2019, 01:11:17 AM »
No. You are wrong. The title is "The Earth is Not Round" and the content of the article reflects that. The article is talking about a globe model that is using the state plane flat maps as their underlying base to get accurate distances. Do your own research on any terms or concepts you find confusing.
« Last Edit: March 25, 2019, 01:14:33 AM by Tom Bishop »

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Offline markjo

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Re: Eratosthenes Experiment Duplicated
« Reply #12 on: March 25, 2019, 01:14:01 AM »
No. You are wrong. The title is "The Earth is Not Round" and the content of the article reflects that. Do your own research in any terms or concepts you find confusing.
Yes, it specifically says that the earth is best described as an ellipsoid and not a sphere.  I'm still not sure that I see your point.
Abandon hope all ye who press enter here.

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If you can't demonstrate it, then you shouldn't believe it.

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Offline Tom Bishop

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Re: Eratosthenes Experiment Duplicated
« Reply #13 on: March 25, 2019, 01:17:27 AM »
No. You are wrong. The title is "The Earth is Not Round" and the content of the article reflects that. Do your own research in any terms or concepts you find confusing.
Yes, it specifically says that the earth is best described as an ellipsoid and not a sphere.  I'm still not siure that I see your point.

It is talking about two models , a flat one and a round one. The round one takes the distances from the flat one, hence the "Earth is Not Round!" title.

Research any terms you find confusing, they are easily found on Google.
« Last Edit: March 25, 2019, 04:19:09 AM by Tom Bishop »

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Re: Eratosthenes Experiment Duplicated
« Reply #14 on: March 25, 2019, 01:19:51 AM »
All of this talk about maps and their accuracy has nothing to do with sticking three sticks in the ground and measuring the length of a shadow.
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Offline markjo

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Re: Eratosthenes Experiment Duplicated
« Reply #15 on: March 25, 2019, 01:34:58 AM »
No. You are wrong. The title is "The Earth is Not Round" and the content of the article reflects that. Do your own research in any terms or concepts you find confusing.
Yes, it specifically says that the earth is best described as an ellipsoid and not a sphere.  I'm still not siure that I see your point.

It is talking about two models , a flat one and a round one. The round one takes the distances from the flat one, hence the "Earth is Not Round" title.
Actually, the flat one is projecting small chunks of round coordinates onto a flat Cartesian coordinate system so that distances can be more readily calculated.

Research any terms you find confusing, they are easily found on Google.
Which of those terms suggests that a flat Cartesian coordinate system is the best way to describe the shape of the earth?
Abandon hope all ye who press enter here.

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If you can't demonstrate it, then you shouldn't believe it.

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Re: Eratosthenes Experiment Duplicated
« Reply #16 on: March 25, 2019, 04:05:36 AM »
If it was an article telling us that the systems were using round earth distances the title of the article would be "The Earth is Round!," markjo.
« Last Edit: March 26, 2019, 02:07:55 AM by Tom Bishop »

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Offline markjo

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Re: Eratosthenes Experiment Duplicated
« Reply #17 on: March 25, 2019, 04:41:37 AM »
If it was an article telling us that the systems were using round earth distance the title of the article would be "The Earth is Round!," markjo.
Then why does the article state that the earth is best described as an ellipsoid?  The article is using "round" to mean "sphere".  An ellipsoid is not a sphere.
Abandon hope all ye who press enter here.

Science is what happens when preconception meets verification.

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Offline WellRoundedIndividual

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Re: Eratosthenes Experiment Duplicated
« Reply #18 on: March 25, 2019, 02:09:53 PM »
Here is further experimental evidence. Peruse at your leisure.

https://core.ac.uk/download/pdf/143365111.pdf

I am still waiting on anyone to tell me if there is something wrong or missing in these experiments.
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Re: Eratosthenes Experiment Duplicated
« Reply #19 on: March 25, 2019, 03:50:22 PM »
Seems pretty clear to me. The only way Eratosthenes could have got a similar result on a flat Earth is if the Sun was a lot (and I mean a lot) closer to Earth than it actually is. We know the distance between the Earth and the Sun very accurately.

As I inferred earlier, Eratosthenes was not and never was setting out to work out the diameter of the Earth as FE Wiki claims. It was widely accepted that the Earth was a sphere in his day so his experiment was to work out the circumference of the Earth and he did that very successfully given the tools available.