문제 — The Problem Archive
Every magnet that has ever been broken reveals the same stubborn truth: cut a bar magnet in half, and you do not obtain an isolated north pole and an isolated south pole. You obtain two complete magnets, each with both poles intact. Yet electricity obeys no such restriction.
In 1931, Paul Dirac posed the question differently. Rather than asking why monopoles do not exist, he asked what would follow if they did. The mere existence of a single magnetic monopole would explain the quantization of electric charge.
In 1982, Blas Cabrera's superconducting detector at Stanford recorded a single event -- a sudden change in magnetic flux exactly consistent with the passage of a Dirac monopole. The event was never repeated.
Grand unified theories predict monopoles were produced copiously in the extreme temperatures of the early universe. These relics would be immensely massive -- roughly 10^16 times the mass of a proton.
The magnetic monopole remains the most beautiful prediction that nature has not yet confirmed. It stands at the intersection of quantum mechanics and classical field theory, of mathematical elegance and experimental persistence.