Though predicted to exist, magnetic monopoles — hypothetical elementary particles with only one magnetic pole — have never been detected by scientists. But physicists have just accomplished the next best thing by actually creating their own synthetic version of these bizarre magnetic particles in the lab.
As any grade 3 student can tell you, every magnet has a north and a south pole. Break that magnet in half, and the pieces will still have a north and south pole. Even if you cut this magnet down to the atomic level, it should still feature bioplar magnetic fields.
Dirac's Conjecture
But back in 1931, physicist Paul Dirac hypothesized about the existence of an elementary particle that's an isolated magnet with only one pole — either a north or a south, but not both. This particle, therefore, would have a net "magnetic charge" while still generating an electric field.
But why should such a particle exist? Dirac said that if magnetic monopoles are an actual thing, then all electric charge in the universe must be quantized. That is, they tidily explain why electrons can't be sliced in half (i.e., the electric charge of subatomic particles always come in discrete units of a fundamental charge). What's more, the existence of magnetic monopoles could also help us answer unresolved questions about space, time, and the laws of physics, including the nature of true symmetry in the universe. Indeed, the Grand Unified Theory predicts them, as does string theory (though some physicists argue that magnetic monopoles are actually dark matter).
If magnetic monopoles are real, they would have likely formed soon after the Big Bang when the conditions were right, when space was considerably hotter and denser than it is today.
But as noted, physicists have yet to produce any true evidence for the existence of magnetic monopoles. Part of the reason is that if they exist, they should be exceedingly rare. There would be less than 1 for every 1029 protons or neutrons. So, if monopoles are distributed evenly in the universe, there should only be a hundred or so in the entire inner solar system!
Polar Vortex
Detecting these elementary particles is obviously proving to be difficult, but that didn't dissuade a team of Amherst College physicists from trying to create their own version of magnetic monopoles.
They did it by cooling rubidium atoms to just a billionth of a degree above absolute zero. By doing so, they forced the atoms into a Bose-Einstein condensate (BEC) — the lowest quantum state possible.
The resulting condensation caused the rubidium to behave differently than normal, creating a cloud that acted like a wave and not a group of individual particles. The scientists manipulated this cloud into a vortex so that all of the particles would align to the same magnetic orientation. Then, after placing a single rubidium atom in the middle, they created a hole completely empty of atoms. The result was the creation of monopole atoms in a synthetic magnetic field.
Evidence, But Not Proof
This is obviously amazing, but it's not irrevocable proof that magnetic monopoles exist in nature. But physicists now have a better understanding of what they should be looking for as the hunt continues. Moreover, this achievement can be construed as actual evidence showing that these elusive elementary particles are actually possible.
Read the entire study at Nature: "Observation of Dirac monopoles in a synthetic magnetic field."
Image: Heikka Valja.
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