Relativity matters: Two opposing views of the magnetic force reconciled

Relativity matters: Two opposing views of the magnetic force reconciled
Gilbertian -- magnetic dipole. Credit: en.wikipedia.org/wiki/Magnetic dipole

Current textbooks often refer to the Lorentz-Maxwell force governed by the electric charge. But they rarely refer to the extension of that theory required to explain the magnetic force on a point particle. For elementary particles, such as muons or neutrinos, the magnetic force applied to such charges is unique and immutable. However, unlike the electric charge, the magnetic force strength is not quantised. For the magnetic force to act on them, the magnetic field has to be inhomogeneous. Hence this force is more difficult to understand in the context of particles whose speed is near the speed of light.

Moreover, our understanding of how a point-particle carrying a charge moves in presence of an inhomogenous magnetic field relied until now on two theories that were believed to differ. The first stems from William Gilbert's study of elementary magnetism in 16th century, while the second relies on André-Marie Ampère electric currents. In a new study just published in EPJ C, the authors Johann Rafelski and colleagues from the University of Arizona, USA, succeeded in resolving this ambiguity between Ameperian and Gilbertian forms of magnetic force. Their solution makes it possible to characterise the interaction of particles whose speed is close to the speed of light in the presence of inhomogeneous electromagnetic fields.

In the new study, the authors present, for the first time, an important insight into how non-homogeneity impacts particle spin dynamics, called spin precession. No prior work has recognised the need to make the form of magnetic torque consistent with the form of magnetic force - the torque was made consistent only with the Lorentz-Maxwell .

This advance allows the impact of field non-homogeneity on precision experiment to be quantified. It seeks to resolve a discrepancy in the understanding of quantum field corrections to the magnetic moment of the muon, an elementary particle often referred to as a "heavy electron."

These findings can be applied to the study of neutrinos, opening the door to realms beyond the standard model of particle physics. Rafelski and colleagues show that the can be large for particles whose speed is very close to the speed of light.


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More information: Johann Rafelski et al, Relativistic dynamics of point magnetic moment, The European Physical Journal C (2018). DOI: 10.1140/epjc/s10052-017-5493-2
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Citation: Relativity matters: Two opposing views of the magnetic force reconciled (2018, January 29) retrieved 17 June 2019 from https://phys.org/news/2018-01-relativity-opposing-views-magnetic.html
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Jan 30, 2018
Could some-one please interpret this in lay-man's language ?
I consider myself a technical guy, but it totally threw me...

Jan 30, 2018
There is an experiment at CERN (called OPERA) where ultra-relativistic neutrinos are produced. It's referred to in another paper by these guys:

https://arxiv.org...7698.pdf

The prime motivation for writing this paper on the theory of ultra-relativistic neutral particles interacting with EM waves is that the researchers propose zapping the neutrinos at CERN with a laser to see how the neutral particles interact with the EM wave from the laser.

They go back to the roots of the theory and find that you need to be very careful about how you handle the higher-level terms when you have an extreme situation such as ultra-relativistic neutrinos. Non-linear terms that drop out at low energy actually are important and must be kept in the equations at speeds very close to the speed of light. An approach combining relativity and Maxwell's equations from the beginning is easier and more clear than starting from Maxwell's equations and then adding correction factors for relativity.

Jan 30, 2018
The second paper also mentions that you need to use the more modern quantum electrodynamic theory that includes the all of interactions between particles and photons. The older Dirac theory has the wrong value for the g-factor - it's measured to be about 2.0023 rather than exactly 2.

https://en.wikipe...physics)

IOW, they are going to extremes in the proposed experiment and are finding that some theoretical terms that don't matter most of the time do matter at the extreme limits. Thus, they need to be careful about keeping them in the equations instead of dropping them out of the equations.

There's another experiment involving muons at Fermilab that also requires careful use of the most comprehensive versions of relativistic quantum electrodynamics.

https://en.wikipe...Muon_g-2

Feb 01, 2018
These and similar problems can not be solved if they do not know what is magnetism, gravity, and matter, and from what and how these phenomena are formed. Nature has solved it much more easily, but at a level that a human being never will be able to accomplish.

Feb 04, 2018
Interesting. Not earth-shattering; keeping track of higher-order terms in extreme situations should be obvious, but this is one of the types of things that gets lost when someone (or, in this case, apparently everyone) forgets it.

Feb 04, 2018
These and similar problems can not be solved if they do not know what is magnetism, gravity, and matter, and from what and how these phenomena are formed. Nature has solved it much more easily, but at a level that a human being never will be able to accomplish.

Unless he's a dizzy blonde Artist...:-)
DS - go to bed, man! I assume you east coast, so it's even later there than here!

Feb 16, 2018
What a magnetic field will form, it depends on the relationship between Aether and free gluons that form magnetism together.

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