The Great Shape Experiment.

One method for determining the shape of the Earth is simultaneously measuring the length of the shadows cast by identical poles perpendicular to a flat surface that is tangential to the earth's radius at various, distant locations.

If indeed the earth is round, then the shadows should all vary in length from one distant location to another, which means that the angle at which the parallel rays of sunlight struck each pole varied from one location to another. (recall the alternate-angles theorem from Geometry class)

If the earth is flat, then the lengths of all the shadows should be identical when measured simultaneously, since all rays of sunlight that strike the earth are parallel. However, they are not identical, but in fact, varies in such a way that the angles indicate a spherical surface.

So in light of this I propose an experiment. In this OP I will post a link to a Google Form for anyone willing to participate in this experiment. So that we can all be sure that we perform the experiment in the same way.

Materials:

There will be a few required materials and you will have time to gather these items to prepare for this experiment:

1) A yard stick (yes, standard American units) or some straight object that is precisely 1 yard long.
2) A measuring device to measure the length of the shadow cast by yard stick.
3) A watch.
4) Paper.
5) Pen.

There will be a few phases to this experiment (which will take place Aug 10 2013 @ 1800 UTC) so that we can gather enough participants for the experiment and they will go as follows:

Phase 1: Sign up (July 20 2013 - August 9 2013)

This part starts today, July 20th 2013.  I have created a form on Google Form's where there will be a set of questions that I will use to gather some basic data:

1) Forum name.
2) Your location on the day of the experiment. The name of the town or city you will be in will suffice.
3) Multiple choice question about shape of Earth.

Click this link to access the sign up form.

Between now and the day of the experiment (August 10 2013 @ 1800 UTC) this Google Form will automatically populate the information you've submitted to the form into a spreadsheet. This spreadsheet is public to anyone with a link so that participants can be assured that I have not manipulated any of the information submitted.

I also suggest that participants mark there calendars ahead of time so that they do not forget when the experiment will take place.

Phase 2: The Experiment (August 10 2013 @ 1800 UTC)

A few minutes before your measurement, bring your materials (yard stick, 2nd measuring device, a watch, paper and pen) outside so that the yard stick will cast a shadow. At precisely 1800 UTC* take your measurement of shadow. You may need someones help to hold the stick while you measure the shadow. Be sure that the entire 1 yard portion of the object you are measuring is above the ground and its shadow is being cast on a relatively flat surface. Once you have measured your findings jot down the length on the paper and pen in millimeters.

* If you don't know what time 1800 UTC is at your location refer to this link to find out what time 1800 UTC is in your location. FYI... on the time table use the time with a D (Daylight Savings) in the abbreviation. For example, if you are using Pacific time use PDT but not PST.

After you have collected your measurement come back to this thread and the link will be available. It will be another Google Form which will collect 2 pieces of information from you:

1) Forum name.
2) Your measurement.

I will post the Measurement Form at the time of the measurement.

Phase 3: Processing & Results

I will not make the results of the Measurement Form public until August 16, 2013. I am doing this so that participants do no fudge their own entries into the form and base them off of previous entries. This will also give participants ample time submit their entries after they have made a measurement.

At some time on August 15, 2013 I will stop accepting measurements for the form and post the results the following day on August 16, 2013. You will see everyone's responses along with your own so that you know that the results have no been manipulated.



This should be interesting.

I am reserving this response to post the link for the Measurement Form shortly after August 10, 2013 @ 1800 UTC.

Is it too much to request a photo of the entire shadow with the measuring device next to it?

On a flat Earth, with a small 30 mile diameter Sun only 3000 miles away, I wouldn't expect the light rays to be parallel. Over a long enough distance to make the measurements meaningful (say 1000 miles or more) I think the rays would diverge on a FE. The parallel rays assumption is only valid when the distance of the light source is very large compared to the Earths diameter.

On a flat Earth, with a small 30 mile diameter Sun only 3000 miles away, I wouldn't expect the light rays to be parallel. Over a long enough distance to make the measurements meaningful (say 1000 miles or more) I think the rays would diverge on a FE. The parallel rays assumption is only valid when the distance of the light source is very large compared to the Earths diameter.

To deal with this you could assess the data on RE and a FE basis and see which results are the best fit?

Is it too much to request a photo of the entire shadow with the measuring device next to it?

If you want to submit a photo then be my guest but I think getting lots of people to submit that data reliably would be tedious. My aim here was to make this experiment simple to do and to automate it.

Consider this though.... there are two forms, the sign up form and the measurement form.

The sign up form will have data immediately accessible by anyone so that we can all see who is participating and know their locations while the measurement forms data will not be accessible for several days after the measurement. Everyone who submits their measurement will be posting numbers without seeing other participant's numbers.

It seems like the length of shadows in different places should still be didn't on a flat earth.

It seems like the length of shadows in different places should still be didn't on a flat earth.

Perhaps if the light source was very, very close.

Seems like nobody here actually wants to do a real experiment... or maybe it's slow cause it's the weekend.

Hi rottingroom! I actually started off in this forum with a similarly themed thread. I never thought of collecting data from everyone using an online form though, nice idea!

Quote from: Shmeggley on July 20, 2013, 10:22:31 AM

On a flat Earth, with a small 30 mile diameter Sun only 3000 miles away, I wouldn't expect the light rays to be parallel. Over a long enough distance to make the measurements meaningful (say 1000 miles or more) I think the rays would diverge on a FE. The parallel rays assumption is only valid when the distance of the light source is very large compared to the Earths diameter.

To deal with this you could assess the data on RE and a FE basis and see which results are the best fit?

Sounds like a plan. However, as far as I know there is no solid prediction from FE to compare to. I think it's a good idea, and if the data fits the RE model that's fine, but I can hear the RE response already: "That's exactly what's predicted on the FE model too!"

Still, I think if we calculate the expected result on the "standard" 30 mile diameter, 3000 mile high Sun circling above the flat disc Earth, it can't match the RE model, so maybe we can rule that FE model out once and for all. I suppose it could still be "saved" by bendy light or some other kludge, but the the onus would be on them to explain precisely how that works.

Quote from: Rama Set on July 20, 2013, 10:25:28 AM

Quote from: Shmeggley on July 20, 2013, 10:22:31 AM

On a flat Earth, with a small 30 mile diameter Sun only 3000 miles away, I wouldn't expect the light rays to be parallel. Over a long enough distance to make the measurements meaningful (say 1000 miles or more) I think the rays would diverge on a FE. The parallel rays assumption is only valid when the distance of the light source is very large compared to the Earths diameter.

To deal with this you could assess the data on RE and a FE basis and see which results are the best fit?

Sounds like a plan. However, as far as I know there is no solid prediction from FE to compare to. I think it's a good idea, and if the data fits the RE model that's fine, but I can hear the RE response already: "That's exactly what's predicted on the FE model too!"

Still, I think if we calculate the expected result on the "standard" 30 mile diameter, 3000 mile high Sun circling above the flat disc Earth, it can't match the RE model, so maybe we can rule that FE model out once and for all. I suppose it could still be "saved" by bendy light or some other kludge, but the the onus would be on them to explain precisely how that works.

Trigonometry's fairly easy. How about on the 8th or so, we pre-calculate expectations for the two main FE models and the RE model based on locations. We can post these prior to doing the test, so everyone can be sure the calculations aren't biased to observations. Then, we use photographic evidence of the observations to ensure we didn't just make up numbers that coincided with the calculations.

Seems like nobody here actually wants to do a real experiment... or maybe it's slow cause it's the weekend.

Bear in mind that anybody in Europe will have to make their own yardsticks, as I don't believe that they are sold in purely imperial units any more in the UK. They will not be available anywhere else in Europe which has been metric for a very long time now.

Quote from: rottingroom on July 20, 2013, 02:55:25 PM

Seems like nobody here actually wants to do a real experiment... or maybe it's slow cause it's the weekend.

Bear in mind that anybody in Europe will have to make their own yardsticks, as I don't believe that they are sold in purely imperial units any more in the UK. They will not be available anywhere else in Europe which has been metric for a very long time now.

When I was in elementary school (in Canada) they had "metre" sticks. For anyone who's interested, in a metric country, just saw the end off at 914 mm.

Quote from: dephelis on July 22, 2013, 10:55:01 AM

Quote from: rottingroom on July 20, 2013, 02:55:25 PM

Seems like nobody here actually wants to do a real experiment... or maybe it's slow cause it's the weekend.

Bear in mind that anybody in Europe will have to make their own yardsticks, as I don't believe that they are sold in purely imperial units any more in the UK. They will not be available anywhere else in Europe which has been metric for a very long time now.

When I was in elementary school (in Canada) they had "metre" sticks. For anyone who's interested, in a metric country, just saw the end off at 914 mm.

Or you could post whether you used a yardstick or a meterstick. The angles will be the same, and that's really what this experiment is about.

Quote from: Rama Set on July 20, 2013, 10:25:28 AM

Quote from: Shmeggley on July 20, 2013, 10:22:31 AM

On a flat Earth, with a small 30 mile diameter Sun only 3000 miles away, I wouldn't expect the light rays to be parallel. Over a long enough distance to make the measurements meaningful (say 1000 miles or more) I think the rays would diverge on a FE. The parallel rays assumption is only valid when the distance of the light source is very large compared to the Earths diameter.

To deal with this you could assess the data on RE and a FE basis and see which results are the best fit?

Sounds like a plan. However, as far as I know there is no solid prediction from FE to compare to. I think it's a good idea, and if the data fits the RE model that's fine, but I can hear the RE response already: "That's exactly what's predicted on the FE model too!"

Still, I think if we calculate the expected result on the "standard" 30 mile diameter, 3000 mile high Sun circling above the flat disc Earth, it can't match the RE model, so maybe we can rule that FE model out once and for all. I suppose it could still be "saved" by bendy light or some other kludge, but the the onus would be on them to explain precisely how that works.

Bendy light is a reality.  Please remember that light bends substantially and this tendency results in the horizontal sinking of many objects by hundreds of feet.  Remember mirages and temperature differences in air and sea and how they effect light please...

Bendy light is a reality.  Please remember that light bends substantially and this tendency results in the horizontal sinking of many objects by hundreds of feet.  Remember mirages and temperature differences in air and sea and how they effect light please...

Lurk moar.  In the context of Flat Earth Theory, bendy light does not refer to the well known and scientifically accepted phenomenon of refraction.  Rather, bendy light refers to the poorly documented and mostly unexplained phenomenon more properly known as Electromagnetic Acceleration that causes light to bend in ways not explained by refraction.
http://theflatearthsociety.org/wiki/index.php?title=Electromagnetic_Accelerator

Quote from: Shmeggley on July 22, 2013, 07:52:21 AM

Quote from: Rama Set on July 20, 2013, 10:25:28 AM

Quote from: Shmeggley on July 20, 2013, 10:22:31 AM

On a flat Earth, with a small 30 mile diameter Sun only 3000 miles away, I wouldn't expect the light rays to be parallel. Over a long enough distance to make the measurements meaningful (say 1000 miles or more) I think the rays would diverge on a FE. The parallel rays assumption is only valid when the distance of the light source is very large compared to the Earths diameter.

To deal with this you could assess the data on RE and a FE basis and see which results are the best fit?

Sounds like a plan. However, as far as I know there is no solid prediction from FE to compare to. I think it's a good idea, and if the data fits the RE model that's fine, but I can hear the RE response already: "That's exactly what's predicted on the FE model too!"

Still, I think if we calculate the expected result on the "standard" 30 mile diameter, 3000 mile high Sun circling above the flat disc Earth, it can't match the RE model, so maybe we can rule that FE model out once and for all. I suppose it could still be "saved" by bendy light or some other kludge, but the the onus would be on them to explain precisely how that works.

Bendy light is a reality.  Please remember that light bends substantially and this tendency results in the horizontal sinking of many objects by hundreds of feet.  Remember mirages and temperature differences in air and sea and how they effect light please...

You're correct. Light refracts as it passes between different mediums (vacuum to air, air to glass, glass to water, water to air, air to air of a different density, etc.). This is a very well-documented phenomena. As light moves from mediums of lower density to mediums of higher density, it is refracted toward the normal (it gets closer to being perpendicular to the border between the mediums).

This means light entering the atmosphere from the sun would be bent downwards, making it appear to be higher in the sky. Likewise, light from, say, a boat far away would be bent downwards as it passes through (or completely reflects off) various low-lying air layers, making something that is really below the horizon appear above it.

Mirages, caused by light bending upwards through or reflecting off (see critical angles) lower-density hot air makes objects' reflections appear lower. Despite these reflections appearing to come from below the horizon, they aren't blocked by the horizon. Thus they cannot explain the sinking ship effect, or the sinking building effect (see photographs of the Chicago skyline from across Lake Michigan).

So yes, light does bend, but except for very special cases (such as a hot surface creating a low-pressure air zone above it) this property makes objects appear higher than they really are.

As a participant in this experiment, I will be sure to take refraction into account when I do my measurements, and add an appropriate degree of error.

May I propose an additional measurement? That is to take note of where the sun is in relation to magnetic north. That is, mark down the compass bearing of the shadow.

you guys... stop making proposals and making decisions about factoring in degrees of error and what not. Just follow the instructions so that everyone performs the same experiment. Holy cow.

Just 6 more days until the Great Day! Finally, we get to have some concrete data on the matter!

Does anybody else want to do this?

For everyone already signed up, be sure to remember!

Does anybody else want to do this?

I'd love to participate, but it will be quite dark for me at the given time. Something to do with the sun being below the horizon...
Oh well! Looking forward to the results!

For everyone already signed up, be sure to remember!

Hmm, I see a flaw in the test that can be dealt with by adding a single measurement. The experiment assumes that the sun's rays will always be parallel, whether the Earth is flat or round. Parallel rays are true for a RE sun 93 million miles away, but the FE sun could be as close as 3,000 miles, and its rays would most certainly NOT be parallel.

If we also took a compass to the shadow and wrote down in what direction the shadow pointed, we would be able to use this information to calculate the apparent location of the Sun (the point on Earth where the yardstick would cast no shadow at all) and even it's apparent altitude above the Earth.

Quote from: Jingle Jangle on July 24, 2013, 10:37:46 AM

Quote from: Shmeggley on July 22, 2013, 07:52:21 AM

Quote from: Rama Set on July 20, 2013, 10:25:28 AM

Quote from: Shmeggley on July 20, 2013, 10:22:31 AM

On a flat Earth, with a small 30 mile diameter Sun only 3000 miles away, I wouldn't expect the light rays to be parallel. Over a long enough distance to make the measurements meaningful (say 1000 miles or more) I think the rays would diverge on a FE. The parallel rays assumption is only valid when the distance of the light source is very large compared to the Earths diameter.

To deal with this you could assess the data on RE and a FE basis and see which results are the best fit?

Sounds like a plan. However, as far as I know there is no solid prediction from FE to compare to. I think it's a good idea, and if the data fits the RE model that's fine, but I can hear the RE response already: "That's exactly what's predicted on the FE model too!"

Still, I think if we calculate the expected result on the "standard" 30 mile diameter, 3000 mile high Sun circling above the flat disc Earth, it can't match the RE model, so maybe we can rule that FE model out once and for all. I suppose it could still be "saved" by bendy light or some other kludge, but the the onus would be on them to explain precisely how that works.

Bendy light is a reality.  Please remember that light bends substantially and this tendency results in the horizontal sinking of many objects by hundreds of feet.  Remember mirages and temperature differences in air and sea and how they effect light please...

You're correct. Light refracts as it passes between different mediums (vacuum to air, air to glass, glass to water, water to air, air to air of a different density, etc.). This is a very well-documented phenomena. As light moves from mediums of lower density to mediums of higher density, it is refracted toward the normal (it gets closer to being perpendicular to the border between the mediums).

This means light entering the atmosphere from the sun would be bent downwards, making it appear to be higher in the sky. Likewise, light from, say, a boat far away would be bent downwards as it passes through (or completely reflects off) various low-lying air layers, making something that is really below the horizon appear above it.

Mirages, caused by light bending upwards through or reflecting off (see critical angles) lower-density hot air makes objects' reflections appear lower. Despite these reflections appearing to come from below the horizon, they aren't blocked by the horizon. Thus they cannot explain the sinking ship effect, or the sinking building effect (see photographs of the Chicago skyline from across Lake Michigan).

So yes, light does bend, but except for very special cases (such as a hot surface creating a low-pressure air zone above it) this property makes objects appear higher than they really are.

As a participant in this experiment, I will be sure to take refraction into account when I do my measurements, and add an appropriate degree of error.

And if there really is a glass/ice sky like some of us believe, we are going to take that into consideration too?  I think we should just stick to the directions...keep it simple.

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And if there really is a glass/ice sky like some of us believe, we are going to take that into consideration too?  I think we should just stick to the directions...keep it simple.
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Yes, I'll factor it into my calculations. It's easy because the maths cancel out the refraction from the ice wall. The difference between the angle of light leaving the ice wall and entering it are the same as if the ice wall wasn't there and the light passed directly from space to atmosphere.

What's so difficult about placing a compass beside the shadow? It's one extra measurement. I'll do all the math and post it somewhere, but this extra measurement is critical to getting true results.

Forget the compass.  If anything substitute the watch for a cell phone.  The time is more trustworthy.  Where I'm located, the sun is in the same general location as the current hour on a clock.  For example, when I was outside at 2pm, looking South, the sun was slightly West of being directly above me (where 12 Noon would be metaphorically).

Alex, please don't factor anything into your calculations.  Just report the shadow measurement.

Forget the compass.  If anything substitute the watch for a cell phone.  The time is more trustworthy.  Where I'm located, the sun is in the same general location as the current hour on a clock.  For example, when I was outside at 2pm, looking South, the sun was slightly West of being directly above me (where 12 Noon would be metaphorically).

Alex, please don't factor anything into your calculations.  Just report the shadow measurement.

I will just report the shadow measurements. But I'm also going to predict what FE says the shadow measurements should be.

The compass would take care of the 'the sun's rays aren't parallel' argument. I don't see what's so hard about setting a compass down next to the shadow. It's one simple measurement that will make this experiment infinitely more valid.

If we also took a compass to the shadow and wrote down in what direction the shadow pointed, we would be able to use this information to calculate the apparent location of the Sun (the point on Earth where the yardstick would cast no shadow at all) and even it's apparent altitude above the Earth.

A suggestion? Rather than using a compass, which does not always point to true north, perhaps put in the extra effort to locate true north and draw a true north-south line at the position you will be placing your yardstick. In the northern hemisphere, this would be easiest done by locating the north celestial pole. In the southern hemisphere, locate the southern celestial pole (a little more fiddly, but it can be done; I did it as a child so that I could make an accurate sundial for a school project). Just a thought to give greater accuracy.

Quote from: Alex Tomasovich on August 07, 2013, 09:01:35 AM

If we also took a compass to the shadow and wrote down in what direction the shadow pointed, we would be able to use this information to calculate the apparent location of the Sun (the point on Earth where the yardstick would cast no shadow at all) and even it's apparent altitude above the Earth.

A suggestion? Rather than using a compass, which does not always point to true north, perhaps put in the extra effort to locate true north and draw a true north-south line at the position you will be placing your yardstick. In the northern hemisphere, this would be easiest done by locating the north celestial pole. In the southern hemisphere, locate the southern celestial pole (a little more fiddly, but it can be done; I did it as a child so that I could make an accurate sundial for a school project). Just a thought to give greater accuracy.

This might be more accurate, but a lot more difficult. The compass'll give accurate enough answers. Plus the deviation from true north is known for various locations. If I get straight compass measurements, I can do the rest myself.