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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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How to describe the dynamics of a magnetic monopole charge in the external EM field using a Lagrangian in terms of the EM potentials?

The equation of motion of a magnetic charge in the fixed external electromagnetic field $\mathbf{E},\mathbf{B}$ is $$ \frac{d}{dt}(\gamma m \mathbf{v})=q_m(\mathbf{B}-\mathbf{v}\times\mathbf{E}), $$ ...
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Dirac's quantisation condition and non-quantised charge

After some time searching for a convincing demonstration of the Dirac quantisation condition, I've finally come across not one but three of them in David Tong's book: Gauge Theory. Nonetheless, it all ...
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Reformulation of Maxwell's equations in the event of finding a magnetic monopole

If we ever obtain empirical confirmation of the existence of magnetic monopoles, how would Maxwell's classical equations be re-written? I'm assuming we'd only need to set the divergence of the ...
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Question about magnetic and electric monopoles

Suppose magnetic monopoles existed. If you had two monopoles, electric and magnetic, what test would you apply to distinguish one from the other?
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How would a magnetic monopole behave around a live wire?

Given a direction of current in a wire, and the magnetic field perpendicular to the wire forms with say "north" pointing clockwise (right-hand-rule convention). If we placed a small monopole ...
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How does the polarity of the magnet changes when flipped upside down? What happens to the direction of magnetic domains and magnetic line of force?

Imagine you have two flat bar magnet with dimensions as $L \times B \times H = 100 \times 50 \times 5$ each. The $B \times H$ side of magnet 1 is facing the $B \times H$ side of the magnet 2. And let'...
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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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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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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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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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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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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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“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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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 Against Fusion Catalyzation of Al-27 Nuclei?

Monopolium is the hypothetical composite of either (1) a bound pair of monopoles, or (2) a magnetic monopole that has captured an atomic nucleus, analogous to how atomic nuclei capture electrons. My ...
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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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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 $$...
HighlyEntropicMind's user avatar
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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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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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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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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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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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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 ...
Sonia Llambias's user avatar
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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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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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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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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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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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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 ...
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It is said that the dual Meissner effect can explain confinement, but where is the Higgs?

It is said that the dual Misner effect can explain confinement. This refers to when the monopole field acquires a v.e.v.. The t'Hooft-Polyakov monopole arises in a theory with a Higgs. So how does the ...
dennis's user avatar
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What do monopoles have to do with strong coupling?

My understanding is that strong coupling effects arise from instantons in the path integral. But I sometimes read that monopoles (see the electric-magnetic duality) can allow one to calculate strong ...
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Making a magnetic monopole using bar magnets [duplicate]

The common bar magnet has the north pole on one end and the south pole on the other. I was wondering if we cut the magnet into the following shape (a part of a thick spherical shell) And then ...
Jonathan Huang's user avatar
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Monopole problem

Original question: So theory predicts that the monople number density at time of GUT was $10^{82}$ per cubic meter, due to inflation it's diluted and today it's about $10^{-16}$ per cubic Mpc. This is ...
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Charged particle in a purely radial magnetic field, is the canonical angular momentum conserved?

Let $ \vec{B} = k \dfrac{\vec{u_r}}{r^2}$ (assuming magnetic monopoles exist) and let $q$ be a charged particle. The associated hamiltonian is $H = \dfrac{(\vec{p} - q \vec{A})^2}{2m}$ and the ...
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What is the physical significance of the negative sign in the lorentz force equation in presence of magnetic monopole?

This question is similar to that of: Why does the extended Lorentz force law have a negative sign? The Lorentz force on a magnetic monopole is given as: $$\vec{F}=q_m(\vec{B}-\vec{v}\times\frac{\vec{E}...
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Lagrangian formulation of Maxwell's equations with magnetic monopole

If we set $\nabla \cdot {\bf B}=\rho_m$ where pm is the density of magnetic charges we lose the ability to write ${\bf B}=\nabla \times{\bf A}$ . Can we get a new Lagrangian that leads to the new ...
CoolerThanACooler's user avatar
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Are magnetic charges compulsory in string theory?

In this penultimate lecture of a series given by Freddy Cachazo, the differential forms corresponding to the massless excitations in the Ramond–Ramond sector signal the existence of p-branes sourcing ...
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EM radiation from monopole v.s. dipole

I'm confused about two conflicting ideas: the first is that monopoles cannot emit EM radiation (see here), and the second is that an accelerating point charge does produce EM radiation (see here). I ...
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What would happen if a magnetic monopole collides with a magnetic antimonopole?

According to Dirac, theoretically, each Magnetic Monopole (North mm) is connected with their counter partner in space, the Magnetic Antimonopole (South mm) via an infinite thin and possible long ...
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Monopoles in the fractual quantum Hall

What role do magnetic monopoles play in the fractional quantum Hall effect? Also see here. EDIT: I should add that I understand the fractual quantum Hall effect only from the perspective of minimal ...
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