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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Non-relativistic vector first integral

In this paper the author discusses the Poincaré vector $\vec D$, and he wrote the Lorentz equation when magnetic charge is present. Do you have any suggested reading for this and how he derived the ...
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Magnetic fields and closed loop

It is well known that there don't appear to be magnetic poles. In Maxwell's equations this has the implication $$ \nabla \cdot \mathbf{B} = 0 $$ and results in the statement "the magnetic field forms ...
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Do magnetic field lines indicate how a mangetic field will act on an “idealized” test magnetic north monopole?

We imagine an electric field and a magnetic field as vector fields. When we are introduced to a static electric field, we usually picture it as an infinite number of vectors (magnitude,direction) in ...
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Some questions on a certain Lagrangian related to $n$ dyons

I am trying to understand Gibbons and Manton's article. I am trying to understand the Lagrangian that they wrote down, from a physical point of view. Let me paraphrase from that article. "Consider $...
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Is Brandt-Neri-Coleman stability analysis valid?

My question is related to the problem of stability of magnetic monopoles in Yang-Mills-Higgs theories. I have read "The Magnetic Monopole 50 years later" from Coleman and, in section 3.5, he discusses ...
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Dirac's Theory of magnetic monopoles

Can someone give a breif summary of Dirac's theory of magnetic monopoles a rather simple way? Please also tell what methods he used and key ideas presented in his paper. I am asking this because it is ...
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Vector potential of magnetic monopole

I am following the step on this introduction to magnetic monopole. I understand that the vector potential produced by semi-infinite solenoid is exactly the vector potential of magnetic monopole. But ...
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Classical Yang-Mills equation of motion with both electric and magnetic sources?

We know the classical Maxwell equation of motion (eom) with both electric and magnetic source can be written as: (1) Explicit form or more schematically as: (2) Differential form $$ d * F = * J_e $$...
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Why separate magnetic poles do not exist? [duplicate]

We are always taught that it is not possible to have separate magnetic poles .Even kn cutting a magnet in half a new magnet are constructed . What is the reason for this unique behaviour ?
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Do magnetic dipoles align with $\mathbf B$ or $\mathbf H$, and why are the two field so closely associated?

As the title says, do magnetic dipoles align with $\mathbf B$ or $\mathbf H$? If one and not the other, why is that? In addition, what force is responsible for causing the magnetic dipoles to align ...
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Can the Dirac quantization condition be derived within Lev Vaidman's formalism without gauge fields?

Textbooks often claim that phenomena like the Aharonov-Bohm effect require that any local formulation of quantum gauge theory use gauge potential fields. (It's also sometimes claimed that the A-B ...
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Conservation of magnetic charge

It is well known that the electric charge of a system can be thought of as the Noether charge associated with isotropic large gauge transformations. That is, given Einstein-Maxwell theory $$S=\frac{1}...
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how much magnetic field is experienced at the centre of bar-magent?

What is the magnitude of magnetic field at the centre of bar magnet? What's its mathematical expression?
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What is the formula for electromagnetic force on magnetic charge in condensed matter?

It is known that if we take into account the magnetic charges, Maxwell's equations acquire a symmetrical form (Jackson, 3rd edition, eq. 6.150): \begin{align} \begin{aligned} -\nabla \times \...
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If monopoles are excised points in a $U(1)$ bundle, how are they affected by other charges?

We currently understand electromagnetism as a U(1) gauge theory. If you take a point out the space manifold (base space) you can create magnetic monopoles with integral charges by making non-trivial ...
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What will be the difference in the behaviour between electric charges and between magnetic charges?

It’s often asked in PSE about the existence of particles with magnetic monopoles. What’s the difference in interaction between magnetic monopoles and electric monopoles in such a theoretical case? ...
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Why can't a particle that carries magnetic charge exist? [duplicate]

Electron is the source of electric field and changing electric field produce magnetic force, what about particle that can do vice versa? My concern is how come universe favors particles that carry ...
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Runaway Monopole Catalyzed Baryon Decay

I am a layman in the subject, but I have recently learned that magnetic monopoles could be used to induce baryon decay (Callan-Rubakov mechanism), according to some GUTs. I have also learned that ...
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How to show monopole term in magnetic vector potential is 0?

Assume we are in a magnetostatic and electrostatic situation. In the multipole expansion of the magnetic vector potential, we end up with $\vec{A}(\vec{r})=\sum_{n=0}^\infty \vec{A}_n(\vec{r})$ ...
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Explanation for magnetic declination [closed]

A compass in New York points about 15 degrees west of true north; in California, it points about 15 degrees east of true north. Magnetic declination also varies with time. What are some possible ...
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Dirac equation and Hamiltonian for a collection of magnetic monopoles

I am trying to understand a mathematical comment by Eugene Wigner in some old lecture$,^{[1]}$ "The Hamiltonian of the Dirac equation for two oppositely charged monopoles is not self-adjoint." What ...
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Why did David Tong say that the global topological $U(1)$ symmetry is unbroken in Higgs phase?

In the paper A Duality Web in 2+1 Dimensions and Condensed Matter Physics by Seiberg, Senthil, Wang, and Witten, they studied the particle-vortex dualities in $2+1$ dimensions. On page 20, section 3....
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Maxwell theory : How to justify the potential gauge fields if there are magnetic monopoles?

Without magnetic monopoles, the Maxwell equations are these (I'm dropping vector notations and all constants, for simplicity): \begin{align} \nabla \cdot E &= \rho_{elec}, \tag{1} \\[12pt] \nabla \...
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Where did the idea that there *might* be magnetic monopoles come from? [duplicate]

I know that we declare that there exist no magnetic monopoles. I see it all the time in my E&M class. $$\vec{\nabla}\cdot\vec{B}=0$$ So there exists no point for $\vec{B}$ to originate from and no ...
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Magnetic Shielding

Imagine a substance in an electric field. You don't want the electric field to interact with the object you have put in its way. What should be the type of material this magnet should be made of to ...
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Does the electrodynamics-like PDE $\epsilon^{ijk}\partial_j B_{kl}(x) = \delta^i_l\delta^{(3)}(x)$ have solutions?

Consider the following PDE in 3 dimensions $$ \epsilon^{ijk}\partial_j B_{kl}(x) = \delta^i_l\delta^{(3)}(x)$$ Does $B_{kl}(x)$ have a solution? (It can have any kind of singularity, e.g. it can have ...
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What actual difference does it make whether electric or magnetic field lines are open or closed?

If both electric and magnetic fields attenuate with distance by the inverse square law, what difference does it make that the latter's field lines are 'closed'? And if a magnetically-induced electric ...
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Field lines of a bar magnet not like electric dipole

It's mentioned that the magnetic field of a bar magnet don't start at one end or end at another (like what happens for a electric dipole), but rather passes "through" the bar magnet like the magnetic ...
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Closed field lines in case of a Bar magnet

Field lines in case of charges go from +ve to -ve but incase of magnet, they dont start or stop anywhere. They form closed loops. Is this consequence of the fact that single poles dont exist or ...
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How did scientists before Coulomb ensured this fundamental property of magnets? [closed]

Firstly, please note that I am talking about the period BEFORE electricity and magnetism were unified. So I am NOT seeking for answers based on Ampere atomic current model of magnets. I have read the ...
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What exactly is meant by magnetic poles?

If I have a magnet, which of the following is really called magnetic pole and why?: $(1)$ Half of the volume of the magnet - north pole, other half volume - south pole. $(2)$ Area at one end of the ...
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A universe with fully symmetric electromagnetism?

Although several extensions to the Standard Model predict the possible existence of magnetic monopoles, their expected properties are rather significantly different from those of the electrically-...
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Definition of magnetic field

Can we define magnetic field at a point as: Force on a point magnetic north pole at that point divided by its pole strength. Anything wrong in this definition? (The concept of point magnetic pole ...
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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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How do we know normal expansion without inflation is not enough to dilute the density of magnetic monopoles?

Assuming magnetic monopoles was produced in the early universe. However we don’t see any of them. Wouldn’t expansion even without inflation dilute their density enough that they are unobservable?
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Does the magnetic field line passing along the axis of a bar magnet ever reaches to South Pole?

Consider a bar magnet, and the magnetic field line that goes through its axis and through the center of its north pole and thus follows a straight line path out of the magnet. Will this line ever be ...
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What is the spin of an electron in the presence of a monopole?

Consider a spinor field in $3$ dimensions, coupled to a $\mathrm U(1)$ gauge field. The spinor has charge $q\in\mathbb N$ spin $1/2$. According to arXiv:1712.00020 (cf. the discussion below eq.2.48), ...
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Is magnetic Field conservative in nature?

Is magnetic field conservative in nature? Magnetic field lines do go in closed paths but that's not the definition of conservative. Rather, a field is conservative when the force on a test particle ...
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Breaking a gauge group through a monopole$.$

I am trying to understand the paper arXiv:1712.08639 and, in particular, the discussion in §5. In this section, the authors take a gauge theory with group $\mathrm{SO}(N)$, and they add a "unit of ...
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If a magnetic monopole travels through a wire loop, which way does the current flow in the circuit?

I am confused about the sign convention for the electric field as described in the wikipedia article "Magnetic_monopole" and I would appreciate some help clarifying the topic. Take a positive (north) ...
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Do the Maxwell equations definitively rule out the existence of magnetic monopoles?

Gauss's law for magnetism, $\nabla \cdot \mathbf {B} =0$, is most directly interpreted as a sort of Kirchhoff's current law for magnetism, stating that while magnetic fields can be drawn between ...
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Linking phase of flux lines and excitation energy of monopole

I am reading this paper and on the left-hand side of pp.10 it states the following relation between linking phase and excitation energy of monopole: Now the $\theta = \pi$ term in the bulk implies ...
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What happens while breaking a Bar magnet?

If we have a bar magnet and we break it as shown below Then as per the image we get two bar magnets But does this happen instantaneously or there is some time lag between this process. Or simply, Can ...
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How much bigger is $a$ than $b$ when we write $a \gg b$?

When a condition of some physical quantity $a$ and $b$ is presented, say $a \gg b$, how much bigger do we say $a$ has to be than $b$? $10$ times? $1000$ times? $10^6$ times? Some context: I am ...
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On the Dirac charge quantisation, bare vs. renormalised$.$

Does the Dirac quantisation condition, $ge\in\mathbb Z$ (and its Schwinger-Zwanziger generalisation) refers to bare charges, or (on-shell) renormalised ones? Both options seem natural to me, at least ...
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Why magnetic field are from south to north pole inside bar magnet? [duplicate]

magnetic field lines are from north pole to south pole outside a bar magnet but its direction is from south pole to north pole inside it. Why and what causes it?
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Arranging solenoids into a sphere to create a magnetic monopole? [duplicate]

[I believe that this question is very different than the question about arranging magnets into a sphere. Solenoids are ruled by Ampere's Law and magnets are not. Ampere's Law is what could make it ...
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Monopole magnets [duplicate]

Let's say I have a set of weak refrigerator magnets. I place these magnets in a complete sphere 1 foot in diameter, with all their south poles facing inward and their north poles facing outward. ...
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How to incorporate Dirac's magnetic monopole solution into a continuous magnetic charge density?

Dirac famously solved Maxwell equations in the presence of a point magnetic monopole. He was able to do so in a manner which used only the standard vector potential $\vec{A}$ and gave the correct ...