Magnetism

Ancient Greeks discovered naturally magnetized iron ore near Magnesia in modern-day Turkey, giving magnetism its name. These "lodestones" baffled philosophers for millennia—Thales believed they had souls because they could move iron without touching it. The mystery deepened when someone realized lodestones always oriented north-south, a property Chinese navigators exploited centuries before Europeans, fundamentally changing maritime exploration and trade.

In 1820, Danish physicist Hans Christian Ørsted was demonstrating electrical circuits to students when he noticed something completely unplanned: a nearby compass needle deflected whenever he switched the current on. This accidental observation during a lecture shattered the belief that electricity and magnetism were separate forces. Within weeks, news spread across Europe, igniting a scientific revolution that would lead to electric motors, generators, and the technological backbone of modern civilization.

Humans may actually sense Earth's magnetic field unconsciously, according to recent experiments showing our brains respond to magnetic shifts even when we're unaware. Some migratory animals like sea turtles and robins have magnetite crystals in their bodies that act as biological compasses, navigating thousands of miles with stunning precision. Scientists are now exploring whether enhancing our latent magnetic sensitivity could help with spatial orientation or even create new assistive technologies for navigation.

James Clerk Maxwell unified electricity and magnetism into four elegant equations that revealed light itself as an electromagnetic wave—arguably the most beautiful achievement in physics. These equations predicted radio waves before anyone had transmitted them and showed that changing electric fields create magnetic fields and vice versa, in an eternal dance. Einstein kept a photograph of Maxwell in his study, calling his work "the most profound and the most fruitful that physics has experienced since the time of Newton."

Magnetic Resonance Imaging exploits the fact that hydrogen atoms in your body act like tiny spinning magnets that align with powerful magnetic fields. When radio waves knock these atomic magnets out of alignment, they emit signals as they snap back—different tissues produce different signals, creating detailed images without radiation. This application of quantum magnetic properties has transformed medicine, allowing doctors to watch brains thinking, hearts beating, and tumors growing, all non-invasively.

Earth's magnetic field has reversed hundreds of times throughout history, and we're overdue for another flip based on geological records. During reversals, which take thousands of years, our magnetic shield weakens dramatically, potentially exposing us to harmful solar radiation and disrupting everything from power grids to animal migration. The field has already weakened 9% in the past 170 years, and the magnetic north pole is currently racing across the Arctic at 34 miles per year—faster than at any point in recorded history.