Physicists have some understanding of how magnets function. However, some phenomena that underlie magnetism continue to elude scientific explanation. Exactly how do magnets work?
Large-scale magnetism, like the kind observed in bar magnets, results from magnetic fields that naturally radiate from the electrically charged particles that make up atoms, said Jearl Walker, a physics professor at Cleveland State University and coauthor of "Fundamentals of Physics" (Wiley, 2007). The most common magnetic fields come from negatively charged particles called electrons .
Normally, in any sample of matter, the magnetic fields of electrons point in different directions, canceling each other out. But when the fields all align in the same direction, like in magnetic metals, an object generates a net magnetic field, Walker told Life's Little Mysteries.
Every electron generates a magnetic field, but they only generate a net magnetic field when they all line up. Otherwise, the electrons in the human body would cause everyone to stick to the refrigerator whenever they walked by, Walker said.
Currently, physics has two explanations for why magnetic fields align in the same direction: a large-scale theory from classical physics, and a small-scale theory called quantum mechanics.
According to the classical theory, magnetic fields are clouds of energy around magnetic particles that pull in or push away other magnetic objects. But in the quantum mechanics view, electrons emit undetectable, virtual particles that tell other objects to move away or come closer, Walker said.
Although these two theories help scientists understand how magnets behave in almost every circumstance, two important aspects of magnetism remain unexplained: why magnets always have a north and south pole , and why particles emit magnetic fields in the first place.
"We just observe that when you make a charged particle move, it creates a magnetic field and two poles. We don't really know why. It's just a feature of the universe, and the mathematical explanations are just attempts of getting through the 'homework assignment' of nature and getting the answers," Walker said.
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