# 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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### Magnetic monopoles in materials

What types of materials would conduct magnetic monopoles well? Would it be materials with a high 'mu' as with regular magnetic fields? Thank you.
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### The most general Maxwell equations

Due to its intrinsic interest. Suppose we want to generalize Maxwell equations without exiting to other (non-abelian) Lie groups. I know the following generalizations: Add magnetic monopoles and ...
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### Do all magnetic monopole models always imply higher symmetry than regular EM?

(Isn't this question asked anywhere before) First, Maxwell equations do not say that magnetic monopoles do not exist. The equations can easily be generalized to include magnetic monopoles. What I want ...
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### Magnetic monopole in CPT universe model

I've recently read this paper CPT universe, and a thought came into my mind. Is it possible to discuss magnetic monopole based on this CPT universe model? This paper points out that some mysterious ...
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### Is there an estimate for how many monopoles would be produced in the very early universe?

The question really hits it with this one. I haven't really found some good numbers other than the whole “It'd be so many (per Hubble vol) to recollapse the universe”. I don't know if that comes of as ...
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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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### 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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