Quick Questions, Short Answers - No Debate

Oh, everyone knows that all penguins are going to heaven. This is abundantly obvious. Except for the one that Batman had to contend with.So, why don't we just wait until after Saturday? Not only that, but then we can scoop up all the empty tuxedoes and start our own Tuxedo Rental business.

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- xongsmith, 5.7d

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Flat earth Txomin: I am interested in the simplest scientific experiment that a layman can carry out in order to determine rough measures regarding the Earth's shape and size. Think high-school education or less, if possible.

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Hi Panda, TxominI did a google on "flat earth test" and also got many hits with examples, however some were from flat earthers showing how they "refuted" the tests and explained how the earth could be flat -- fascinating reading. I thought this site was the best:http://www.lhup.edu/~dsimanek/flat/flateart.htm

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3. The variation of the sun's elevation with latitude. (This was the basis of Eratosthenes' measurement.)

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The Round Earth.

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Eratosthenes (c 276 to 195 BCE) was probably the first to accurately measure the size of the Earth. He knew that at summer solstice the sun was directly overhead in Syene (now Aswan, Egypt). On that day, vertical sticks or poles cast no shadows, and sunlight fills the bottom of wells. The town of Alexandria is directly north of Syene (on the same meridian), and on that same day vertical poles do cast shadows, because the sun is then 7.2 from the zenith. Eratosthenes assumed this to be due to the earth's curvature.

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Knowing the distance between these cities to be 5000 stadia (from land surveys), he calculated the earth's circumference to be 250,000 stadia. [1 stadium was 1/8 of a Roman mile, or 220 yards in modern measure.] That's a circumference of a little over 24,662 miles, which is nearly the modern value of 24,900 miles. ...

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Note that Eratosthenes made the assumption that the sun was far enough way from the earth that the incoming solar rays are parallel.

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Rethinking Eratosthenes.

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One can reconstruct the origin of these numbers by doing a little geometry, starting from a flat earth hypothesis. Remember the experiment of Eratosthenes, who measured the angular elevation of the sun at two latitudes in Egypt? He assumed that the sun was effectively infinitely far away (or at least so far compared to the earth's size that the actual distance didn't matter). Then he calculated the diameter of the earth using a second assumption: that the earth was spherical.

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But suppose you abandon Eratosthenes' two assumptions, and adopt instead the assumption that the earth is flat. Then, triangulation from the same data gives the distance to the sun: 3000 miles! See how a simple change of assumptions can drastically alter the entire cosmos? However, the round earth was more than an arbitary assumption for Eratosthenes, for he and his contemporaries, had other very good reasons for knowing the earth was round. [Textbooks sometimes mislead by suggesting that his experiment was designed to prove the earth was a sphere. It was not, it was only intended to measure the size of the sphere.]

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Finally, the angular size of the sun is 0.5. Using this fact with a distance to the sun of 3000 miles, gives the sun's diameter: 32 miles. It therefore appears that the flat-earther's figures are based on sun elevation data at just two particular latitudes, perhaps even Eratosthenes' values. I speculate that flat earthers may have picked these out of some book, and when the calculation was finished, they looked no further. For if they had done the calculation with a variety of latitudes, including large latitude differences, conflicting results would have been obtained.

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Still, one could save the hypothesis by assuming that light refracts in a peculiar way. Modern flat-earthers do indeed assume that refraction is at work. They attribute the disappearance of the ships over the horizon to a refraction effect, and even point out that with some atmospheric conditions, ships, icebergs, and distant mountains have been observed to rise above the horizon, and even turn upside down!

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Turning upside down demonstrates that it is a mirage reflection. I have seen this phenomenon from the middle of Lake Michigan looking both east and west.With modern equipment and watches we can now repeat Eratosthenes' experiment with observations made at the same time from different longitudes as well as different latitudes,
and establish a grid of measurements, each with their distance known from a set zero point that becomes the timer for the measurements when the sun is directly overhead.Enlist a bunch of high schools from around the world to participate.Then you could make a list of predictions from each hypothesis and test for them against the resultsCould be a fun project.Enjoy.

From the article you linked, it seems like Flat-Earthers end up having to claim massive conspiracies and deny gravitational forces to maintain their beliefs.
The article didn't address satellite photography - but I guess that would fall under the 'conspiracy' heading.)

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At the outer edge lies the southern ice, reputed to be a wall 150 feet high; no one has ever crossed it, and therefore what lies beyond is unknown.

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Why haven't flat-earthers gone and photographed the edge?
And is 150ft really too high to cross?!?I think without testing the shape of the earth: the level of conspiracy required to make people believe a flat earth is spherical is beyond credibility.
I am happy with the current lay-man's tests because to disbelieve them means up-rooting too many other established facts (including gravity).
If a flat-earther wants to go and photograph the edge of the world, I will be fascinated to see the results.

Hello Panda and RAZD, It may be beyond your credibility but we should start teaching it in science classes just in case.Your round earth theory is not the only option you know

There is a video where His Holiness Carl Sagan shows how the earth's circumference was measured waaaaayyyy back when. I'm at work and can't remember what video it was. Youtube somewhere, I'm sure. Something about shadows....Edited by hooah212002, : No reason given.

Hi Butterflytyrant, Panda, etc. Yes, we should teach both sides of the controversy and let the students decide ... Enjoy

In addition, I would think that the dip angle (not listed as such, but idea is included in the article on the horizon) might work.One visual clue that we were taught about is how a ship leaving port appears to disappear as it goes over the horizon but its upper superstructure remains visible. This also comes into play when two ships at sea need to be within a particular distance of each other to begin to see each other; the top of the mast is always the first part to appear. The higher up the observer is, the farther out he can spot something, which is why a lookout would be placed in the crow's nest and why search radar's antennas are placed high on the ship.In astronomy, the horizon extends out horizontally from the observer; ie, at right angles to the vertical. The true horizon, where the sky meets the ground, is below that. At what angle lower (AKA "dip angle") depends on the altitude of the observer (the greater the altitude, the lower the dip angle) and, if I recall correctly, on the radius of the earth (the smaller the radius, the greater the dip angle).The mathematics can be left as an exercise for the student.

When this icon appears on my taskbar ... ... I've never found any way to get internet access again except to restart my computer. There must be a better way, does anyone know of one?Thanks.

Sometimes TOTO your modem can help.
Your modem might include some software for monitoring/repairing your broadband connection.
Also, I think you can also right-click the icon and select 'Repair'.
But, unfortunately, sometimes you just have to TOTO your PC. :SIf it is happening regularly, then there could be a problem with your broadband. Ask your IP to check it out.(This is not something I am trained in per se, but it is something I have a much experience of.)

Open up a command prompt, then type in then, when the ip is flushed, type (note a space after ipconfig)However, there could be a number of reasons for this happening and the above will only resolve the issue if it is due to your machine. for example, on my Windows 7 Ultimate machine right now, I get the same icon when my modem loses connectivity even though my PC's IP address is fine because my router acts as a DHCP server. It is apparently indicating to me a loss of internet connectivity, whereas prior versions of windows did not do this.Edited by hooah212002, : No reason given.

I sometimes see that on a Vista computer. It is typically caused by rebooting the router (either deliberately, or the router just decided to reboot).If I unplug the ethernet cable, and leave it unplugged for a minute or two, then I often get a connection back when I restore the cable. I'm not sure that works every time. When trying that trick, I normally unplug the router end of the ethernet, since that is more easily accessible than the computer end.This did not happen with a previous computer. I am not sure if this behavior is due to hardware (presumably the ethernet card), or due to the change from XP to Vista.On my normal desktop, I see something similar with linux, if the NetworkManager software is managing the network. If I switch to using init scripts, I don't have similar problems.

I've noticed, especially on Vista/Win 7 platforms, a lot of network-related weirdness caused by the IPv6 drivers (Toredo IP Tunneling, etc), up to and including random BSOD's. I'm recommending that everybody experiencing persistent internet weirdness uninstall their IPv6 drivers (which is a bit of a complicated process, since you have to both uninstall the drivers and disable IPv6 support with a registry key, otherwise they just reinstall at next bootup.)These drivers are just abominable and they solve a "problem" that nobody has, yet.

Interesting. Thanks.

Alas, it says: One possible reason for this is that when I opened up the command line, it said:

i am on my phone because my internet is down ATM, so my resources are limited, but I found this: answers.yahoo.com/question/index?qid=20090131123734AAYJyuG.what os are you running? hopefully the problem isn't something worse than a simple IP error.....forgive my formatting, it's not fun doing HTML on a phone...