# Questions tagged [magnetic-monopoles]

A magnetic monopole is a hypothetical particle with only one magnetic pole. Their magnetic fields would not be divergence-less. Predicted by certain modern theories, including string theory, supergravity, and various popular grand unified theories.

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### Is it possible to introduce magnetic monopoles without breaking $∇ · B = 0$?

In another word, the net magnetic charge is always zero everywhere, which means magnetic field is still strictly source free. On the other hand, the net magnetic current jm can be nonzero, which means ...
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### Maximum $B$-field at the surface of a permanent magnet

I have the dipole formula for a permanent spherical magnet in coordinate-free form. $\vec{B}=\frac{\mu_{0}}{4\pi}\frac{3(\vec{m}\cdot\hat{r})\hat{r}-\vec{m}}{r^{3}}$ I am trying to find the maximum $B$...
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### Why are magnetic monopoles "incompatible" with quantum mechanics?

I'm reading this Physics Today article on magnetic monopoles, and I'm a bit confused by a discussion of the necessity of Dirac strings for compatibility with quantum mechanics. I'll reproduce the ...
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### On rotating magnetic charges

Consider a sphere with magnetic charge $P$ and electric charge $Q$. We know that when the sphere is subjected to rotation about the $z$-axis, there is a magnetic dipole moment generated from the ...
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### Is charge not quantized fundamentally and that is why we haven't come across magnetic monopole?

If protons are getting charged from quarks.. then the charge in quarks is fractional and not quantized. Does this mean that the charge we see is not fundamental? And the charges in quarks are just ...
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### Can cosmological defects escape a black hole?

Based on my understanding, anything that can't move faster than light can't get out of a black hole, but space can since it can move faster than light (hence cosmic inflation is exponentiated). Also, ...
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### Magnetic field with periodic boundary conditions, torus and magnetic monopoles

Suppose I have a 2D square lattice in the xy-plane, and I apply a uniform magnetic field in the z-direction. To simplify calculations, I would like to assume periodic boundary conditions in both the x ...
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### Berry flux of magnetic monopole

I am sorry if it looks stupid question. I want to ask how sin is transferred back from spherical to Cartesian and how $F_{ij}$ tells us about magnetic monopole in magnetic field. $F_{ij}$ is berry ...
1 vote
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### Why would magnetic monopoles not violate the law of conservation of energy?

The field lines around a magnetic dipole are continuous unending loops. If magnetic monopoles were to exist, we could limit the path of a monopole along one of these field lines where it will continue ...
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### Have magnetic monopoles been predicted to have been produced in other cases than those of symmetry breaking in GUTs?

Also, what other configurations are magnetic monopoles theorized to exist in? (such as black holes, monopole walls etc.)
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### How can holographic duals (eg. AdS/CFT) be used to study magnetic monopoles? [closed]

What useful things are possible to find out about magnetic monopoles through the use of dual theories? I'm thinking of characteristics such as stability (or chaoticness), expectation values, central ...
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### Possible charge for Abelian and non-Abelian theory

I am reading Tong's lecture note gauge theory. On page 6 in chapter 1 he writes Instead, the key distinction is the choice of Abelian gauge group. A $U(1)$ gauge group has only integer electric ...
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### Suppose an isolated north pole exists. Then would it surely move along magnetic field line of a bar magnet as written in my book?

My book says that magnetic field lines due to a bar magnet are the path along which a unit north pole would move (if it existed). Will it surely move along the field line? I mean the two poles of ...
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### Is an electron a topological defect? [duplicate]

Magnetic monopoles such as the t'Hooft Polyakov monopoles are special field configurations within some SU(2) gauge theory, that are characterised by their non trivial topology, thus calling them one ...
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### How to derive Dirac's quantization of electric and magnetic charge from Berry's phase?

I have seen two ways of deriving Dirac's quantization of electric and magnetic charge using Berry's phase, one from Sakurai's book Modern Quantum Mechanics P354~355 and the other from David Tong's ...
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### Cosmic strings, domain walls, and magnetic monopoles are topological defects, but what's defecting?

Wikipedia gives an explanation of cosmic strings that I'm sure would be very helpful if I had a major in topology, but alas I do not. I know that a topological defect is any sort of discontinuity in a ...
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### Why monopoles of magnets do not exist? [duplicate]

Why monopoles (in magnets) do not exist?
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### What particles are thought to have existed before Inflation?

What fundamental particles do most Grand Unified and Inflationary theories predict existed before the Inflationary period? Basically, what do we expect the family of particles existing during the ...
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### Are current loop and magnets 100% equivalent?

let's consider this picture taken from Wikipedia, It is written that: A magnetic dipole is the limit of either a closed loop of electric current or a pair of poles as the size of the source is ...
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### How would a magnetically charged particle behave in matter?

Magnetically charged particles, or "magnetic monopoles", are a type of hypothetical elementary particle that may exist, though likely are very rare and/or hard to generate if they do. As the ...
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### Is this case a failure of Stokes' theorem?

In the presence of a hypothetical magnetic point charge at the origin of coordinates, it turns out that an irremovable physical singularity of the vector potential ${\bf A}({\bf r})$ exists for any ...
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### Force law from Lagrangian for magnetic monopole

How to construct a Lagrangian that gives the Lorentz force law with both magnetic and electric monopole? I got that the force will be of the form m \frac{\mathrm{d}x^\nu}{\mathrm{d}\...
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### Magnetic monopole Lagrangian and Hamiltonian

How do I find an equation analogous to \mathcal{L}(q,\dot q)=\frac12 m \dot q ^2-q\phi+q\vec{\dot q}\cdot \vec A\quad\quad \text{where}\quad \vec B =\vec\nabla\times\vec A, \quad \vec ...
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