On the Trail of the Elusive Magnetic Monopole Break a magnet into two pieces, and what do you obtain? What you get, unsurprisingly perhaps, are two new magnets - each one with two sides of opposite polarity. You don't get a north half and a south half. Back to square one, it seems... Ever since Paul Dirac developed a comprehensive theory of magnetic monopoles in 1931, physicists have been eager to isolate these hypothetical particles featuring a north or south pole only.