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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Dirac's quantization rule
I first recall Dirac's quantization rule, derived under the hypothesis that there would exit somewhere a magnetic charge: $\frac{gq}{4\pi} = \frac{n\hbar}{2} $ with $n$ a natural number.
I am ...
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Why is Magnetism at the centre of a bar magnet zero?
I have seen some sources saying
"Magnetism at the centre of a bar magnet is zero."
and Some sources say
"Magnetic field at the centre of a bar magnet is zero."
Please help me ...
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Why curl of Dirac string attached to Dirac monopole is zero?
So let we have a magnetic field which is
$$B_\mu=\frac{q}{2}\frac{x_\mu}{|x|^3}-2\pi q\delta_{3\mu}\theta(x_3)\delta{(x_1)}\delta{(x_2)},\tag{4.65}$$
where $\theta$ is step function and $\delta{(x_\mu)...
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Magnetic monopoles in spin ice and Dirac string comparison
In spin ice systems magnetic monopole-like excitations are sources or sinks of $H$, not the $B$ field, why is that? Is it because the strings carries magnetic moment $M$ and not solenoidal $B$ filed ...
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Dirac strings are classically observable through induction?
For my Masterthesis I will have to dive a bit into Dirac monopoles, which are said to be pairwise connected by a Dirac string which is just an infinitesimal fiber carrying magnetic flux $|\vec{B}|=g$. ...
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Magnetic Monopoles and Its Antimatter and Mirror Particle Counterparts [closed]
I'm trying to understand how magnetic monopoles and how its potential mirror and antiparticle counterparts would behave. So according to the modified lorentz force law
$$\vec{F}=q_e\left(\vec{E}+\frac{...
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Transplanckian energy magnetic monopoles in string theory/M-theory
I was thinking about transplanckian energy $E>10^{19}GeV$ magnetic monopoles in string theory and M-theory. Are they possible in Nature like the Dirac, 't Hooft Polyakov, Julia-Zee monopoles/dyons? ...
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Is it possible for electroweak monopoles to catalyze electroweak burning?
Given that both electroweak monopoles and the Sphaleron process involve the non-trivial aspects of electroweak interactions, I am curious about whether there is theoretical or experimental evidence to ...
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Moving charge to define magnetic field
Why charged particle has to be in motion to define magnetic field?
Will magnetic force exert any force on a static charge? (as in the static test charge in electric field)
A line from my book reads-
"...
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How does magnetic charge in string theory arise?
In string theory, all of the standard model charges (electric, color, and weak hypercharge) arise from Kaluza Klein theory and through the interactions between strings and branes.
But little is said ...
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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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Magnets in 2 Spatial Dimensions?
In 2+1 dimensions of spacetime, the electromagnetic field is made up of a vector electric field and a scalar magnetic field. At each point in space, there is a magnetic field value, which we can ...
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Vector potentials that give monopole magnetic fields with good properties [duplicate]
I am looking for a vector potential
$$\mathbf{A}=(A_x,A_y,A_z)$$
giving a monopole magnetic field
$$\mathbf{B}=\mathbf{\nabla}\times \mathbf{A}= g\frac{\mathbf{r}}{r^3} = g \left( \frac{x}{r^3}, \frac{...
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“Emergent magnetic monopole” discovered (5th December 2023)
Looks like a few days ago (5th December 2023) a research team discovered “emergent magnetic charge” in antiferromagnetic materials, and the result was published on Nature Materials.
The finding was ...
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Least action principle for Dirac monopole
I want to find the Lorentz force formula for the magnetic charge through the principle of least action. The magnetic charge is introduced by Dirac adding inside the electromagnetic tensor a tensor $G^{...
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Would monopoles exist in numbers that cancel out?
Suppose magnetic monopoles exist.
Is there a reason to think that as much north monopole must exist as south, or even that if one exists then so must the other (could there be south without north or ...
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What sort of QED-like theories can have non-quantized charge?
It is often said that the existence of a single monopole would force electric charge to be quantized, due to Dirac's argument. However, one can write down theories like QED that, independently of the ...
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Is it possible to make an electromagnet have south poles formed at both ends?
As far as I am concerned, all magnets have 1 N and 1 S pole, but I think I
might be missing something.
Is it possible to make an electromagnet have south poles formed at both ends?
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Is Monopolium Theoretically Stable?
Monopolium is the hypothetical composite of either (1) a north-south pair of monopoles, or (2) a magnetic monopole that has captured an atomic nucleus, analogous to how atomic nuclei capture electrons....
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Monopole Spherical Harmonics
I was following Yakov Shnir his book about magnetic monopoles, there they derive the monopole spherical harmonics. I will sketch the derivation briefly,
The starting equation is the eigenvalue ...
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Berry curvature Weyl and Dirac points
I understand that Berry curvature sinks and sources correspond to Weyl points. However, I'm curious about the identity of points exhibiting a Berry curvature spiral, highlighted by red circles in the ...
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Magnetic Reissner-Nordstrom Black holes
I am studying the RN black hole from Carroll, but i have a hard time following his explanations given in page 254.
To solve for the purely electrically charged black hole, one introduces the four-...
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Why there are no Dirac $B $ boson monopoles?
This differs from an earlier post in that the writing is new and hope better, it uses MathJax, and it gives some details about the particle that poses a problem for certain commonly used theories of ...
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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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Why do compasses always align with the magnetic field, when the spin of individual particles only align half of the time?
If I have an electron orbiting a nucleus and I apply a magnetic field there will be two effects:
Larmor precession given by the cross product of the magnetic moment and the field of the experiment
$$...
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Magnets arranged in a sphere
If I was to take a bunch of magnets and arrange them in a sphere (And keep them there with glue or plastic or something) so that the north pole faces the outside of the sphere and the south pole faces ...
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Single-valuedness of the monopole harmonics
It is known that it is impossible to have a non-singular vector potential for the monopole magnetic field.
How about the monopole harmonics?
Could the wave functions be made single-valued and finite ...
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Why are there no diccussions of hypercharge conservation or Dirac hypercharge monopoles?
The Maxwell equations can be derived from an equation for a spin 1 field with $U(1)$ symmetry. From this field equation is possible to postulate Dirac monopoles by simply roting the real and complex ...
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Why is the monopole problem a problem?
According to this Wikipedia article on cosmic inflation:
The magnetic monopole problem, sometimes called the exotic-relics problem, says that if the early universe were very hot, a large number of ...
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Could there exist a Magnetic equivalent to the Schwinger Limit?
The Schwinger limit is a scale above which the electromagnetic field is expected to become nonlinear.
It's associated with the Schwinger effect where It is a prediction of quantum electrodynamics (QED)...
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How do Magnetically charged black holes behave
The existence of Magnetic monopoles has not been proven or disproven.
There are equartions for Charge black holes, There are equations for Rotating black holes, but are there equations for ...
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Joining Magnets to Make Larger Uni-Pole
I would like to know;
if it is possible to force magnet wedges (as seen in picture) together to form a "Uni-Pole Radial Ring Magnet?"
Also, if it is possible to force smaller "Uni-...
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Contracdicting qualitative statements regarding magnetic polarization
Consider a cube of metalic material (either it is paramagnetic or diamagnetic can be both discussed). An external magnetic field $\textbf{B}$ is applied along the +x axis.
We expect $\textbf{B}$ to be ...
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Dirac String force?
Assume that the Dirac string is lying along the negative $z$-axis, and is subject to a magnetic field $B$. Assume throughout this question that we are considering a static situation. The force on the ...
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Is there an explanation for why electric charge, or hypercharge, are rational multiples of each other? [duplicate]
Electromagnetic charges are obviously quantized - I suppose the lowest charge being the $d$ charge of $e/3$. Every other charged particle has a multiple of that charge (actually all stable free ...
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Electric and magnetic field strength of a magnetic monopole. (In absence of electric charges.)
According to Wikipedia, in the presence of magnetic monopoles Maxwell's equations will look like:
Whilst the potentials will look like:
So my question is, how would the electric and magnetic field ...
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Self-duality of Maxwell lagrangian in terms of magnetic gauge field
I have read at many places that the pure Maxwell theory (without any matter) is self-dual. This is the general form for Maxwell Lagrangian density:
$$\mathcal{L} = - \frac{1}{4} F_{\mu\nu} F^{\mu\nu},$...
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Gilbert dipoles vs Ampere dipoles
In Griffiths' textbook there is this problem :
His solution is that you can't tell whether it's Gilbert or Ampere because in the cavities the field would be the same but I don't understand why is ...
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Dirac string and nature of singularities
The Dirac magnetic monopole is defined as
\begin{align}
\vec{B}=\frac{g\vec{r}}{r^3}\,,
\end{align}
where $g$ is the strength of the monopole and $\vec{r}$ a vector. It is possible to show that the ...
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How would I go about detecting magnetic monopoles?
A question needed for a "solid" sci-fi author: How to detect a strong magnetic monopole? (yes, I know no such thing is to be found on Earth).
Think of basic construction details, principles of ...
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How do they know Magnetic Field Lines run from South to North inside a magnet?
I get how they can plot the field lines outside the magnet, but how do they know how it runs inside the magnet to form a closed loop? Isn't the direction fo the field lines the direction of the force ...
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Electricity and magnetism monopoles
If a bar magnet is spun about its north-south axis, an electric field is produced, which is directed radialy outward in all directions.
As the length of the north-south axis is reduced, while keeping ...
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Is the Dirac monopole quantization condition out by 1/2?
Consider an electron with electric charge $e$ that is moved around a closed horizontal circular path $C$ centered around a magnetic monopole with magnetic charge $g$. Assume that the monopole produces ...
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Can Maxwell's equations be derived from Coulomb's Law and Special Relativity?
As an exercise I sat down and derived the magnetic field produced by moving charges for a few contrived situations. I started out with Coulomb's Law and Special Relativity. For example, I derived the ...
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Magnetic field due to singular gauge transformation
In $SU(2)$ gauge theory over $\mathbb R^3$, consider the following gauge transformation (in spherical polar coordinates)
$$ \Omega=\begin{bmatrix}e^{i\phi}\cos(\theta/2)&\sin(\theta/2)\\-\sin(\...
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Large and small gauge transformations
I've a question about the definition of 'large' gauge transformations. There are two competing definitions:
small gauge transformations are equal to the identity at spatial infinity while large gauge ...
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If principle $SU(N)$ bundles on 3-manifolds are trivial, how can there be magnetic monopoles?
Magnetic monopoles are solitons, i.e. field configurations on space (which is 3 dimensional). In pure $SU(N)$ gauge theory, magnetic monopoles can be constructed via 't Hooft's abelian projection (...
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Creation of Magnetic Monopoles using Black Holes
If a very long bar magnet is made and is allowed to free fall in a black hole, a point will come when exactly the north pole is inside and south pole is outside the event horizon for a very small ...
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How is this term an angle?
This question is regarding the $\Theta_{\mu\nu}$ term given in equation (3.8) of the paper (https://arxiv.org/abs/2206.07725). The term ( I have typed it below )is defined right below in (3.9) and ...