POLE POSITION“Early Plates,” by Marissa Grunes [Advances], states that Earth’s magnetic north pole is “technically” now in the Southern Hemisphere. Can readers get an explanation of this?ALEX SMITH LITTELTON, MASS.On supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.GRUNES REPLIES: The terms “north” and “south,” as applied to magnetic poles, are somewhat arbitrary designations. Imagine a bar magnet: Magnetic force flows out of what we call its “north” pole. The force bends…