Flat earther, “That Guy”, deeply misunderstands magnets and how their three-dimensional fields.  He even misunderstands this so much that he imagines a single magnet with the north polarity at the geographic north pole is somehow “proof” that the earth is flat.  Of course, this is very from reality as there are several ways this fails to match observations.

• In addition to the North Magnetic Pole (NMP), there is a well known and thoroughly documented South Magnetic Pole (SMP).
• The locations of the magnetic poles move constantly.  The location has been documented for centuries and confirmed through additional other mechanisms.  This is in line with the current scientific understanding of how the earth’s magnetic field is generated.  A single, permanent magnet like he suggests doesn’t explain the movement.  There is no proposed flat earth scientific explanation for the movement of the two magnetic poles.
• Because of the general location of the poles, the magnetic north and geographic north are not the same.  This difference is called declination.  This has been measured and documented for centuries.  Quality maps include the current magnetic declination at the time of printing as part of the legend.  Knowing the declination is vital information for navigators as a slight deviation from your intended heading can have a major impact on the progress and success of the journey.
• If the SMP were introduced into the flat earth map at the observed SMP location, the magnetic declination would not match in any way.
• The earth’s magnetic field is not regular.  The field has variations.  These are documented and included in the centuries of magnetic declination records.  These also match the current scientific understanding of how the earth’s magnetic field is generated.  There is no proposed flat earth idea that supports these observations.
• Magnetic Inclination or Magnetic Dip is the downward measured angle of the earth’s magnetic field lines.  Positive dip is when the needle points down and positive dip is when the needle points up.  The dip must be increasingly positive closer to the NMP and increasingly negative as you get closer to the SMP.  This has been observed and documented for centuries.  If the earth were flat the inclination would be drastically different than observed.
  • You can measure this yourself with a dip meter.
  • You might also use a global compass as a dip meter.  This requires that the needle be evenly balanced.  Be sure to verify before accepting the results from a compass that is not specifically claiming to be a dip meter.
• The strength of the earth’s magnetic field is also well documented.  The strength is lowest far from the magnetic poles and strongest near the magnetic poles.  The observed magnetic field strength matches the current scientific understanding of how the earth’s magnetic field is generated.  There is no proposed flat earth idea that supports these observations.