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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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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120 views

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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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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280 views

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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3answers
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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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479 views

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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211 views

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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1answer
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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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1answer
122 views

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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1answer
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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 ...
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Can we have $\nabla\cdot B \neq 0$ and still no magnetic work?

I had an argument with a friend who says that it's possible to have a force that does no work on monopoles with $\nabla \cdot B \neq 0$. I believe this is not possible, as if we imagine approaching ...
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Monopoles from hypothetical Weinberg-Salam model with massless Z boson

We know that no monopoles exist in the Weinberg-Salam model (a good explanation is provided in the answer to this previous question). Now let us assume that the initial $SU(2)\times U(1)$ gauge ...
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No global monopoles in QCD

If a global symmetry gets both spontaneously and explicitly broken, the explicit symmetry breaking pattern is crucial for understanding the formation of topological defects. For example, in the axion ...
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Question about Monopole Operator

I've been studying IR-dualities in 2+1 dimensions. I encountered monopole operators in the following paper: Time-Reversal Symmetry, Anomalies, and Dualities in (2+1)d On page 10, starting from $...
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Question about Charge and Gauge Transformation

Does gauge invariance imply charge neutrality? I understand that all physical observables must be gauge invariant. Does this mean that physical observables must be neutral? If a quark is in red, a ...
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Why won't this magnetic levitation system work?

According to Earnshaw's theorem, a system of static magnets cannot be stable. I have a though experiment and I'm wondering what would happen in real life. If one were to take a ball and cover it with ...
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Magnetic monopoles and the Poynting vector

Assume that magnetic monopoles exist. Let us have one charge(for example, an electron) of electric charge $q_e$ at the origin and one magnetic monopole particle of magnetic charge $q_m$ separated by a ...
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698 views

Is a magnetic monopole really necessary for charge quantization?

The usual remark that goes about in a first encounter of Dirac monopoles is that it solves the problem of electric charge quantization. I have also studied t'Hooft Polyakov monopoles which ...
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If they were freely available, what would be potential applications of the magnetic monopole?

viz., if the magnetic monopole (the hypothetical fundamental particle, not the fauxmonopole behavior in BECs) was discovered, and then found to be abundant or easily produced, what could they be used ...
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Could there be equivalence between anisotropic space and the presence of a field? [duplicate]

What if we are so used to the curvature of space caused by mass and the range of its effects that we totally ignore the possibility of the existence of "opposite" curvature1, i.e. objects that bend ...
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157 views

Electric field produced by magnetic monopoles current density

We know the magnetic field produced by electric current density...if we add the magnetic monopoles what would be the electric field produced by this magnetic monopoles current density?
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How to derive Gauss's law for magnetism? [closed]

We know how to derive Gauss's law for electric field from Coulomb's law but i need to know how to derive Gauss's law for magnetism from biot-savart law?
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Vector Potential for Dirac's String

I've been doing some research on magnetic monopoles and I always end up seeing an expression for Dirac string vector potential commonly as: $$\textbf{A}=g\frac{1+\cos\theta}{r\sin\theta} \hat{\phi}$$ ...
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Can you make electricity from the bound charges in magnets?

Magnetostatics is the study of magnetic fields in systems where the currents are steady. If inside magnets that give off magnetic fields there are bound charges, is there any possible way to make them ...
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168 views

What happens if I put one pole of a magnet beyond the horizon of a black hole?

Let's assume I could lower a bar magnet slowly from some position outside of the Schwarzschild horizon. What happens if it crosses the horizon, so that one pole of the magnet is inside the black hole ...
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1answer
222 views

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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Is there either a Lagrangian or a Hamiltonian formulation of electromagnetism with continuous distributions of magnetic monopoles?

Maxwell's equations generalize very nicely if we add in magnetic monopoles: we get $$\begin{align*} \partial_\mu F^{\mu \nu} &= J^\nu \\ \partial_\mu \tilde{F}^{\mu \nu} &= \tilde{J}^\nu, \end{...
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Why do we need poles?

The electric force is the attraction or repulsion between charges. If we for example had a metal with only positive charges, and another metal with only negative charges. The two metal pieces will ...
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What are the physics principles behind magnetic strength and distances [closed]

This is for my report and I wanna know what are the theory behind why magnets repel. Why magnetic force decreases as distance increases. I wrote down one of the theory, magnetic field but I'm not sure ...
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Dirac's quantization of electric charge

I was following Nakahara's book Geometry, Topology and Physics, specifically subsection 10.5.2. I do understand how he obtains the equality, $$ \Delta \varphi = \int \mathrm d\varphi = \int \limits^{...
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What was Dirac's motivation to study hypothetical magnetic monopoles?

The equation $$\boldsymbol{\nabla}\cdot\textbf{B}(\textbf{r})=0\tag{1} $$ dictates that there can be no isolated magetic monopole. What was then the motivation for Dirac to consider the consequences ...
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198 views

Magnetic field generated by magnetic monopole?

My goal is to show that a magnetic field generated by a magnetic monopole is $$-\frac{1}{2r^2}\hat{r}$$ but I'm having a little trouble doing so. I know that $$\vec{\nabla}\cdot\vec{B} = 4\pi \rho_M $...
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Why does Monopole in $D=3+1$ not drive a compact $U(1)$ gauge theory into a Confined Phase?

In compact $U(1)$ gauge theory, it has confined/deconfined phase. For $D=2+1$, monopole (2$\pi$-flux) event can always drive a system into a confined phase, as shown by duality mapping to a Sine-...