How about this proof?

OK, anyone who lives near the coast can do this one. This is how the ancient egyptians proved that the earth is round.

Go to the shore with a good pair of binoculars, or a telescope. you should wait for a ship to sail off, or show up when you know a ship will be sailing away. Watch the ship as it sails away. As it gets farther and farther away, it will start to dissapear. First the bottom of the ship wil not be visible, and slowly more and more wont be visible, from the bottom up. It will look like the ship is slowly sinking into the sea. This is because as the ship goes away, it follows the curvature of the Earth, meaning that it is curving down from you. But your line of sight is still perfectly streight. So the ship becomes less visible from the bottom up. The earth is blocking part of it. I'll attatche a pic to show this better.

I screwed up the picture. here's a link to it
http://www.rcgroups.com/forums/attachment.php?attachmentid=759575

OK, anyone who lives near the coast can do this one. ... I'll attatche a pic to show this better.

Okay, this one has already been done to death.  Basically, flat-Earthers claim that this could just as easily be explained by their theory, because somehow waves would block your view of the ship.  Please don't berate me on this; I'm just repeating what they say.

Thanks for the nifty picture though.

-Erasmus

thanks, I looked around and couldn't see anything about it.

Here's another one. The Earth has a magnetic field. There is a north side and a south side, just like the poles on a magnet. Anyone with a compass can see this. Under the flat earth theory the north pole is in the center. But a magnet with the one pole in the center and one pole all around the border can't exist. The poles must be on opposite sides of the object. The only way the earth can have a magnetic field that is oriented the way it is is if the earth is spherical, or any shape where the poles are at opposite ends.

Here's some pictures of what happens in the FE world.  The first image shows a ship up close on a flat Earth.  Notice the height of the waves.  The ship is "hull up" to the viewer, because nothing occludes the hull.



In the next illustration, the ship is farther, so there are more waves in between the viewer and the ship.  However, the waves are not any higher; the viewer can still see all the parts of the ship that he could see before: the ship is still "hull up".



No matter how far away the ship gets, there will always be a line of sight to the viewer.

-Erasmus

The poles must be on opposite sides of the object.

Do you know enough about elecromagnetism to say for sure (like, with proof) that no object can have a point north pole and a curve containing the north pole for a south pole?  Thus field lines would radiate out from the hub along the surface of a torus of inner radius zero.

-Erasmus

A magnet is formed by a group of polar molecules. Lots of material is made of polar molecules (water for one) but in a magnet the molecules are all lined up, such that thier positive side is all facing one direction, and the negative side is facing the other. This is what makes the magnet. In a center-pole magnet, all of the molecules would have thier positive end facing the center, and the negative end facing out. As far as I can tell, This would be impossible. The atoms would repell each other, i.e. all push out from the center. the molecules would probably spin around so that they face the same direction. Another possibility is that all of the dipoles would cancel out, because every dipole would have a dipole facing in the opposite direction. This is sort of what happens with non-magnetic polar materials.

I'm not positive of this description, but I am reasonably sure. The fact that I have neverr seen or heard of a center pole magnet adds empiracle evidence to my arguement.

A magnet is formed by a group of polar molecules.

...or by a moving electrical charge (how the round Earth generates a magnetic field).  There are no "lined up" dipoles in the round Earth's core.

-Erasmus

right, that too. Anyway, it has been confirmed, a magnet with one of the poles in the center is impossible.
Flat Earth theory predicts that the Earth will have no magnetic field, or at least one that does not line up north-south. The earth does have a magnetic field, and it does in fact line up from north to south, therfore flat earth theory has been disproven.
QED

it has been confirmed, a magnet with one of the poles in the center is impossible.

I'm sorry, I missed the part where it was confirmed...

Actually, what we're arguing about is not whether an object can have a pole in its center, but whether it can have a pole that is a curve instead of a point, such that the curve contains the opposite pole.

Flat Earth theory predicts that the Earth will have no magnetic field, or at least one that does not line up north-south.

Where does it predict that?  Maybe you need to answer the "Where was it confirmed that this is impossible?" question first.

QED

Use this jargon sparingly, please.

-Erasmus

Here's some pictures of what happens in the FE world.  The first image shows a ship up close on a flat Earth.  Notice the height of the waves.  The ship is "hull up" to the viewer, because nothing occludes the hull.



In the next illustration, the ship is farther, so there are more waves in between the viewer and the ship.  However, the waves are not any higher; the viewer can still see all the parts of the ship that he could see before: the ship is still "hull up".



No matter how far away the ship gets, there will always be a line of sight to the viewer.

-Erasmus

I do think someone tried to demonstrate that by saying that the waves would stack up the further away you got. when you told him about the ant thing... kinda like so :

I do think someone tried to demonstrate that by saying that the waves would stack up the further away you got.

Yeah, that's obviously incoherent though.  I'm pretty sure my picture is a more accurate representation of what's going on: waves are more or less always the same height, unless a storm intervenes or something (and the ship-horizon effect works even if there's no storm in between us).

Anyway, I only reentered this discussion because I was in a mood to draw pretty pictures (thanks for contributing yours, btw).

-Erasmus

Hate to point this out bt I think I also mentioned magnetism several times myself as an FE flaw. Also Erasmus whats up in your drawings I don't see what the RE point is.
An intrigued
Cinlef

Hate to point this out bt I think I also mentioned magnetism several times myself as an FE flaw. Also Erasmus whats up in your drawings I don't see what the RE point is.
An intrigued
Cinlef

The drawings illustrate ships on a flat Earth.  The point is to notice that there's no reason for waves to get any higher as the ship gets farther from the viewer.

sorry erasmus. I forgot to tell you, I looked it up, and asked about it on physicsforums. It is impossible to have a maget with a pole in the center and the other pole as a ring around the outside. A flat earth could not have a magnetic field where one pole is at the north pole, and the other is at the south pole. Because magnetic north is always in the direction of the north pole (generally) then a flat earth could not exist, at least not one where the north pole is in the center.

sorry erasmus. I forgot to tell you, I looked it up, and asked about it on physicsforums. It is impossible to have a maget with a pole in the center and the other pole as a ring around the outside. A flat earth could not have a magnetic field where one pole is at the north pole, and the other is at the south pole. Because magnetic north is always in the direction of the north pole (generally) then a flat earth could not exist, at least not one where the north pole is in the center.

Well, perhaps there could be multiple magnets, each with the positive at the north pole and the negative at the south. Of course the magnetism at the south 'pole' would be weaker as the magnets are moe spread out.

sorry erasmus. I forgot to tell you, I looked it up, and asked about it on physicsforums. It is impossible to have a maget with a pole in the center and the other pole as a ring around the outside. A flat earth could not have a magnetic field where one pole is at the north pole, and the other is at the south pole. Because magnetic north is always in the direction of the north pole (generally) then a flat earth could not exist, at least not one where the north pole is in the center.

Well okay, I believe you, but I would like to see an explanation as to why it's impossible.  I'm generally mistrustful of, well, "forum science".  Basically all you've told me is that somebody on another forum agrees with somebody on this forum about an obscure and possibly-not-often-discussed-in-physics-courses aspect of physics.  But fine, I concede.

-Erasmus

Erasmus is the Leonardo da Vinci of MS Paint.

sorry erasmus. I forgot to tell you, I looked it up, and asked about it on physicsforums. It is impossible to have a maget with a pole in the center and the other pole as a ring around the outside. A flat earth could not have a magnetic field where one pole is at the north pole, and the other is at the south pole. Because magnetic north is always in the direction of the north pole (generally) then a flat earth could not exist, at least not one where the north pole is in the center.

Sorry, but I have to poke a hole in your statement.  I believe that people told you it's impossible.  And they should, because you were asking the wrong question.  A thin disc with the north pole in the center and the south pole on the edges is pretty much impossible, even without attempting some Maxwell's equation on it.  Just drawing the magnetic lines would tell you that (magnetic lines cannot have sharp turns, which they would have to at the "north pole" of this disc).

However, the flat earth is the top of a cylinder with the top as north pole, and the bottom as south pole.  You would get the same effect as if the edges of that cylinder is the south pole, if you were limited to only the flat top disc of that cylinder.

Am I making any sense with this?  The edge of the FE would not be the real magnetic south pole, just the effective magnetic south pole.

Of course, in this model, the magnetic field would weaken the further one is from the magnetic north pole, which is not at the exact center of Flat Earth, but pretty close.  Although I suspect that magnetic field varies a bit on the real Earth, I also suspect that it becomes stronger near the magnetic north pole (which currently is not at the "top" of the real Earth, but somewhere in the seas off northern Canada) and also near the magnetic south pole.

Another possibility may be that FE is not a thin, solid disc, but a torus, just like a CD, DVD, or LP, and the inside edge is north while outer edge is south pole.  Although I'm not too sure if this magnetic configuration is possible.

Erasmus is the Leonardo da Vinci of MS Paint.

Actually, I use xfig!  It's way nicer.  Don't know if there's a version for Windows, though.

-Erasmus

the flat earth is the top of a cylinder with the top as north pole, and the bottom as south pole.  You would get the same effect as if the edges of that cylinder is the south pole, if you were limited to only the flat top disc of that cylinder.

I don't know; I think "I_am_me" has a point.  Are you sure you would get the same effect as if the edges (sides, I guess) of the cylinder is the south pole?  Not sure.  I guess, like you say, since you're so close to the north pole, that's going to overpower the fact that the south end of the needle doesn't really point to the south pole of the planet.

Hm.

-Erasmus

Yes, you are both correct.  Now that I've thought about it more, the effect could not be exactly the same.  After all, if the north-pole-center magnetic disc cannot actually exist, one cannot approximate its field anyway.  The closest approximation is the torus magnet, which I'm not too sure can exist either.

However, I'm convinced that it could be similar, at least in that all compasses on this surface will point out "North" and "South" in the FE-correct fashion: North being toward the center, and South toward the edge/side.

Recall the toy/experiment with iron filings on a piece of paper and a magnet underneath pointing with the north pole straight up:  While the filings form spikes directly above the magnet, the spikes point outward from the "center" of the magnet's upper surface.

It is a very awkward explanation of the magnetic field of FE, and can be disproved by a North-South road-trip experiment as well.