SoylentNews is people
SoylentNews
From EurekAlert (Australian National University):
Physicists have found a radical new way [to] confine electromagnetic energy without it leaking away, akin to throwing a pebble into a pond with no splash. The theory could have broad ranging applications from explaining dark matter to combating energy losses in future technologies. However, it appears to contradict a fundamental tenet of electrodynamics, that accelerated charges create electromagnetic radiation, said lead researcher Dr Andrey Miroshnichenko from The Australian National University (ANU).
"This problem has puzzled many people. It took us a year to get this concept clear in our heads," said Dr Miroshnichenko, from the ANU Research School of Physics and Engineering. The fundamental new theory could be used in quantum computers, lead to new laser technology and may even hold the key to understanding how matter itself hangs together.
"Ever since the beginning of quantum mechanics people have been looking for a configuration which could explain the stability of atoms and why orbiting electrons do not radiate," Dr Miroshnichenko said. The absence of radiation is the result of the current being divided between two different components, a conventional electric dipole and a toroidal dipole (associated with poloidal current configuration), which produce identical fields at a distance. If these two configurations are out of phase then the radiation will be cancelled out, even though the electromagnetic fields are non-zero in the area close to the currents.
Dr Miroshnichenko, in collaboration with colleagues from Germany and Singapore, successfully tested his new theory with a single silicon nanodiscs between 160 and 310 nanometres in diameter and 50 nanometres high, which he was able to make effectively invisible by cancelling the disc's scattering of visible light.
Nonradiating anapole modes in dielectric nanoparticles and arXiv PDF.
(Score: 3, Informative) by c0lo on Monday August 31 2015, @01:15AM
Seems like. EM is usually taught in terms of E and B. Looks like the things change in a quite interesting if adopting a potential approach.
gauge fixing [wikipedia.org] - transforms the classical EM in QED using potential functions (instead of their derivatives E,B). Then toroidal moment [wikipedia.org] and the experimental confirmation by Aharonov–Bohm effect [wikipedia.org].
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by eof on Monday August 31 2015, @02:14PM
Potential functions (the electric potential and the vector potential) are not at all unique to quantum mechanics or QED. Even basic undergraduate courses in E&M introduce the electric potential--it is what differences in potential measured by voltmeters refers to. Choice of gauge (gauge fixing) and field moments are also well known classical concepts.
The Aharonov-Bohm effect is a quantum phenomena dealing with the effect of the potential functions on the phase of the wavefunction. It has no classical analog, although it would fall under the general label of a Berry phase which does have both classical and quantum manifestations.
(Score: 2) by c0lo on Tuesday September 01 2015, @03:11AM
But not the magnetic vector potential
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 0) by Anonymous Coward on Tuesday September 01 2015, @04:21AM
I don't know what E&M you learned, but it is literally on the cover (Griffiths [amazon.com]) of one of the undergraduate books on my shelf. Didn't you ever learn the reasoning for there not being magnetic monopoles? I learned Maxwell's Equations as an undergraduate (even had it on a tee shirt).
(Score: 2) by eof on Tuesday September 01 2015, @06:47PM
Freshman/sophomore level courses don't often introduce the magnetic vector potential (some do); it more often is taught in junior/senior level courses, and definitely graduate courses.