[phayes9891]

How would a geomagnetic reversal work on a flat earth?
There is evidence all over the world that supports pole reversals, just look into mid ocean ridges or lava flows. When the molten rock is cooled magnetic minerals inside of the rock will orient towards the magnetic north pole. Every 100,000 to 1 million years or so the poles switch, meaning the south pole has been the magnetic north pole.
The wiki describes our magnetic field as a radial magnet, which sure explains why we find minerals pointing towards the North Pole, but when the poles are reversed that would mean the minerals would be pointing all over the place, to whichever "edge" it had the most attraction to. We don't find that, the minerals in fact are pointing in one direction towards the South Pole.

[TotesNotReptilian]

There is nothing particularly special about the north magnetic pole compared to the south magnetic pole. If the magnetic pole reversed, everything would work exactly the same except everything is flipped around. The magnetic south pole of a magnet would point north (inward) and the magnetic north pole would point south (outward), instead of vice versa.

[phayes9891]

You are right about the inward/outward North/South comparison, but that doesn't account for inclination. I am assuming the radial magnetic field is horizontal, like the few diagrams I was able to find. After thinking about it a little more, I didn't even need to bring in magnetic reversals to make my point. If the earth were flat you would not see inclination (magnetic dip), which can also be seen with a compass.
Here is a link to further explain it, though this link is referring to a planes compass it is still the same idea as magnetic minerals in a rock:

http://www.bwrs.org.au/sites/default/inline-files/Barrington/Analysis/JohnWatson/Watson%20Dip,%20MC%20errors.PDF


 

[TotesNotReptilian]

You are right about the inward/outward North/South comparison, but that doesn't account for inclination. I am assuming the radial magnetic field is horizontal, like the few diagrams I was able to find. After thinking about it a little more, I didn't even need to bring in magnetic reversals to make my point. If the earth were flat you would not see inclination (magnetic dip), which can also be seen with a compass.
Here is a link to further explain it, though this link is referring to a planes compass it is still the same idea as magnetic minerals in a rock:

http://www.bwrs.org.au/sites/default/inline-files/Barrington/Analysis/JohnWatson/Watson%20Dip,%20MC%20errors.PDF

I disagree. Imagine a disk positioned above the north pole of the magnet. You would get a very similar dip pattern. The main difference would be the strength of the field. If the earth was flat, the magnetic field would be much weaker in the south than in the north, because of how much farther away from the source it would be.

[phayes9891]

If that were the case, you would get similar results in the northern hemisphere but not in the southern. Also, around the equator with that model you would see a dip, but there is no dip at the equator.

[TotesNotReptilian]

If that were the case, you would get similar results in the northern hemisphere but not in the southern. Also, around the equator with that model you would see a dip, but there is no dip at the equator.

On the diagram in the pdf that you linked, look at the top word "dip". The field line directly above that word would be parallel to the flat earth. You would have to move the surface of the earth up a bit until the horizontal part of the field lines match up with the equator. I suspect that you are correct that the field directions in the Southern Hemisphere wouldn't match up exactly, but they would be sort of close. Keep in mind, flat earthers don't even have a working map yet. It's hard to verify the exact direction of the magnetic field when you don't even have a map to work with.

Just playing devil's advocate, don't mind me...

[phayes9891]

Not a problem at all I was hoping for comments like this, I find it pretty interesting, it's nice to have something to think about now that I'm just working and not in school haha.

I think I understand what you're saying, this would be so much easier if we could just draw pictures on here haha. So you're picturing the field to look the same as a bar magnet, except its a disc with the southern end being the outer circle and the northern point being the center. If that is the case I think I was wrong, it would actually look pretty similar. Though after looking more into radial magnets I think we've been looking at it wrong because the magnetic field for a radial magnet is pretty different from a bar magnet.

This is the best link I've seen so far: http://www.animatedscience.co.uk/ks5_physics/general/Electricity%20&%20Magnetism/Magnetic%20Fields.htm

It sounds like the magnetic field from the radial magnet has to be parrallel to the source, in the example they're talking about a speaker, so the field is parrallel to the coil. So basically for our planet to have a radial magnetic field there would have to be a large magnetic type cylinder or object in the middle with a conductor wrapping around it, and another magnetic object outside of that. So, they could say its similar to the core. Maybe there would be the solid inner "core" (iron), a liquid middle "core" (nickel-iron), and another solid outer "core" () in a frisbee shape with the middle liquid core circling inbetween the two solid cores. Then the mantle is outside and above that. Not sure if that would even be possible due to pressure and temperature, possibly if the outer core was made of something with a higher melting point than nickel or iron like aluminum or copper, but it would have to be less dense as well otherwise it would just move to the center, aluminum is less dense than iron...

Anyway if all that is even possible then the magnetic field would be parrallel to the ground, and we shouldn't see a dip anywhere. 

[TotesNotReptilian]

Not a problem at all I was hoping for comments like this, I find it pretty interesting, it's nice to have something to think about now that I'm just working and not in school haha.

Gotta keep the hamsters running or they get fat and lazy.

I think I understand what you're saying, this would be so much easier if we could just draw pictures on here haha. So you're picturing the field to look the same as a bar magnet, except its a disc with the southern end being the outer circle and the northern point being the center. If that is the case I think I was wrong, it would actually look pretty similar.

Pretty much. The main problem is the decreasing strength of the field as you travel south (towards the outer edge), represented by the field line density.

Though after looking more into radial magnets I think we've been looking at it wrong because the magnetic field for a radial magnet is pretty different from a bar magnet.

This is what I assume they mean by a "radial magnet": imagine a bunch of bar magnets arranged in a circle with the north ends facing the middle. Incidentally, this could solve the strength issue I mentioned above. And the angles still approximately match up. Neat! I have no idea how such a magnet would be produced inside earth though. Perhaps two counter-rotating currents? Like two rings stacked on top of each other, each rotating the opposite direction?

Here is a lazy approximation of what the field lines would look like:

This is the best link I've seen so far: http://www.animatedscience.co.uk/ks5_physics/general/Electricity%20&%20Magnetism/Magnetic%20Fields.htm

It sounds like the magnetic field from the radial magnet has to be parrallel to the source, in the example they're talking about a speaker, so the field is parrallel to the coil. So basically for our planet to have a radial magnetic field there would have to be a large magnetic type cylinder or object in the middle with a conductor wrapping around it, and another magnetic object outside of that.

Do you mean ferromagnetic objects? The purpose of wrapping a current around an iron core has to do with the permeability of the iron, not its status as a permanent magnet.

So, they could say its similar to the core. Maybe there would be the solid inner "core" (iron), a liquid middle "core" (nickel-iron), and another solid outer "core" () in a frisbee shape with the middle liquid core circling inbetween the two solid cores. Then the mantle is outside and above that.

If I am picturing it correctly, that would produce the same field lines as a bar magnet.

I think what you are thinking of is a circular solenoid. Basically, the exact inverse of a bar magnet. (The current and magnetic field lines are reversed). This would indeed produce field lines that would be parallel to the flat earth, but they would also be pointing east-west instead of north-south. Minor problem. (Edit: Crossed out the stuff that is wrong. There would be no magnetic field on the surface.)

[phayes9891]

The decreasing strength towards the "outer edge" makes since with the normal bar magnet.

This is what I assume they mean by a "radial magnet": imagine a bunch of bar magnets arranged in a circle with the north ends facing the middle. Incidentally, this could solve the strength issue I mentioned above. And the angles still approximately match up. Neat! I have no idea how such a magnet would be produced inside earth though.

I was thinking of that as well, but wouldn't the North ends of the "magnet" repel eachother? I would assume that would create some problems at the magnetic North pole. If they didn't repel eachother would there be a gray area in the middle of all the northern ends of the bar magnet. Say you were standing on the surface in the middle would your compass just start spinning in circles? Would the magnetic fields of the various bar magnets overlap or do you think they would combine?
Do you think the Northern ends could just end up combining, something would have to be circulating, so could it just end up turning into a normal radial magnet?

Perhaps two counter-rotating currents? Like two rings stacked on top of each other, each rotating the opposite direction?]

I honestly have no idea haha.

Do you mean ferromagnetic objects? The purpose of wrapping a current around an iron core has to do with the permeability of the iron, not its status as a permanent magnet.

Yes, I think that's what I was referring to.

If I am picturing it correctly, that would produce the same field lines as a bar magnet.

I think what you are thinking of is a circular solenoid. Basically, the exact inverse of a bar magnet. (The current and magnetic field lines are reversed). This would indeed produce field lines that would be parallel to the flat earth, but they would also be pointing east-west instead of north-south. Minor problem.

Oh ok, I'll look into circular solenoids. That was just my attempt to think of a mechanism that could cause that type of field, since they really don't explain anything, probably just googled it and said that kind of makes since and stuck in the wiki.

[TotesNotReptilian]

If I am picturing it correctly, that would produce the same field lines as a bar magnet.

I think what you are thinking of is a circular solenoid. Basically, the exact inverse of a bar magnet. (The current and magnetic field lines are reversed). This would indeed produce field lines that would be parallel to the flat earth, but they would also be pointing east-west instead of north-south. Minor problem.

Oh ok, I'll look into circular solenoids. That was just my attempt to think of a mechanism that could cause that type of field, since they really don't explain anything, probably just googled it and said that kind of makes since and stuck in the wiki.

Actually, I'm pretty sure my description of of the magnetic field of a circular solenoid was wrong. I should've stopped to think about it for more than 2 seconds.

Edit: Yep, I was wrong. Google confirms it. The correct term is "toroid", and the magnetic field outside the toroid is zero. Darn Ampere's Law.