Amherst Researchers Create Magnetic Monopoles

An anonymous reader writes "Nearly 85 years after pioneering theoretical physicist Paul Dirac predicted the possibility of their existence, an international collaboration led by Amherst College Physics Professor David S. Hall '91 and Aalto University (Finland) Academy Research Fellow Mikko Möttönen has created, identified and photographed synthetic magnetic monopoles in Hall's laboratory on the Amherst campus. The groundbreaking accomplishment paves the way for the detection of the particles in nature, which would be a revolutionary development comparable to the discovery of the electron." That's quite a step beyond detecting monopoles; the Nature abstract is online, but the full paper is paywalled.

Comments

Re:Contradicts current theory?

[dkf]

Theory (due to Paul Dirac's work combining quantum mechanics and relativity in the first half of the 20th Century) had been predicting monopoles for a long time. Yeah, the simplified version that you were quoting from didn't predict monopoles, but the full version did. If the submitters of the paper have found one of these rare beasts in the lab, that's a very interesting confirmation.

The real question is whether the result can be reproduced by different experimenters in a different lab. (Since it's lab-scale work, that ought to be possible.) If so, watch out for some really interesting new areas of physics to be opened up.

Pseudoparticles

[Sockatume]

These are pseudoparticles. They're like magnetic monopoles in almost all ways, but they arise from the collective motion of other particles rather than actually existing in and of themselves (think about having an electron hole, versus having an actual positron). The breakthrough is that they've made the first pseudoparticle in a quantum mechanical regime that allows it to behave consistently with the real particle.

Re:Pseudoparticles

[radtea]

They're like magnetic monopoles in almost all ways...

Correct. The ways they don't behave like magnetic monopoles are scale-dependent. At sufficiently large distances they are indistinguishable from point-like monopoles (monopole equivalents of electrons.) At short distances they aren't anything like monopoles.

The theory they are based on, curiously, predicts that they are free in the medium they exist in, which was something of a surprise. That is, in an infinite BEC, they would be free to move anywhere, making them much more like "true" monopoles than expected.

Whether or not you call these "real" monopoles is a matter of taste. The reality is that at sufficiently large distances no experiment you could perform would be able to distinguish them from a monopole particle, making them extremely practical mechanisms for investigating the physics of monopoles.

One interesting thing is that Dirac showed the existence of a single monopole anywhere in the universe could explain why the electron charge was quantized, because for a given monopole strength there is only one value of electron charge that can interact with it consistently (any other value requires the electron wavefunction to have multiple values at same point in space-time, which would imply a breakdown of quantum mechanics.) I don't know if these pseudo-monopoles are sufficient to impose that condition.

Re:Contradicts current theory?

[MozeeToby]

Well, they created a magnetic monopole but they didn't create a magnetic monopole. :) They created a magnetic field without it's corresponding opposite field (or actually the opposing field was separated by enough physical distance that they behaved independently), but they didn't create or detect the particle which in theory generates that field.