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Science
Related: About this forumWeyl points, predicted in 1929, observed for the first time
http://newsoffice.mit.edu/2015/Weyl-points-detected-0716Cool
Part of a 1929 prediction by physicist Hermann Weyl of a kind of massless particle that features a singular point in its energy spectrum called the Weyl point has finally been confirmed by direct observation for the first time, says an international team of physicists led by researchers at MIT. The finding could lead to new kinds of high-power single-mode lasers and other optical devices, the team says.
For decades, physicists thought that the subatomic particles called neutrinos were, in fact, the massless particles that Weyl had predicted a possibility that was ultimately eliminated by the 1998 discovery that neutrinos do have a small mass. While thousands of scientific papers have been written about the theoretical particles, until this year there had seemed little hope of actually confirming their existence.
Every single paper written about Weyl points was theoretical, until now, says Marin Soljačić, a professor of physics at MIT and the senior author of a paper published this week in the journal Science confirming the detection. (Another team of researchers at Princeton University and elsewhere independently made a different detection of Weyl particles; their paper appears in the same issue of Science).
Ling Lu, a research scientist at MIT and lead author of that teams paper, says the elusive points can be thought of as equivalent to theoretical entities known as magnetic monopoles. These do not exist in the real world: They would be the equivalent of cutting a bar magnet in half and ending up with separate north and south magnets, whereas what really happens is you end up with two shorter magnets, each with two poles. But physicists often carry out their calculations in terms of momentum space (also called reciprocal space) rather than ordinary three-dimensional space, Lu explains, and in that framework magnetic monopoles can exist and their properties match those of Weyl points.
For decades, physicists thought that the subatomic particles called neutrinos were, in fact, the massless particles that Weyl had predicted a possibility that was ultimately eliminated by the 1998 discovery that neutrinos do have a small mass. While thousands of scientific papers have been written about the theoretical particles, until this year there had seemed little hope of actually confirming their existence.
Every single paper written about Weyl points was theoretical, until now, says Marin Soljačić, a professor of physics at MIT and the senior author of a paper published this week in the journal Science confirming the detection. (Another team of researchers at Princeton University and elsewhere independently made a different detection of Weyl particles; their paper appears in the same issue of Science).
Ling Lu, a research scientist at MIT and lead author of that teams paper, says the elusive points can be thought of as equivalent to theoretical entities known as magnetic monopoles. These do not exist in the real world: They would be the equivalent of cutting a bar magnet in half and ending up with separate north and south magnets, whereas what really happens is you end up with two shorter magnets, each with two poles. But physicists often carry out their calculations in terms of momentum space (also called reciprocal space) rather than ordinary three-dimensional space, Lu explains, and in that framework magnetic monopoles can exist and their properties match those of Weyl points.
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Weyl points, predicted in 1929, observed for the first time (Original Post)
Recursion
Jul 2015
OP
bvf
(6,604 posts)1. Lost me at "momentum/reciprocal space,"
but I love this sort of thing.
Thanks, Recursion.
drm604
(16,230 posts)2. So Weyl points are magnetic monopoles?
That can't be right.
Recursion
(56,582 posts)3. There is a phase space in which they are magnetic monopoles
They are not monopoles in inertial 4-space.
drm604
(16,230 posts)4. Obviously this is outside my field of knowledge.