What is Monopole: Definition and 67 Discussions

In particle physics, a magnetic monopole is a hypothetical elementary particle that is an isolated magnet with only one magnetic pole (a north pole without a south pole or vice versa). A magnetic monopole would have a net "magnetic charge". Modern interest in the concept stems from particle theories, notably the grand unified and superstring theories, which predict their existence.Magnetism in bar magnets and electromagnets is not caused by magnetic monopoles, and indeed, there is no known experimental or observational evidence that magnetic monopoles exist.
Some condensed matter systems contain effective (non-isolated) magnetic monopole quasi-particles, or contain phenomena that are mathematically analogous to magnetic monopoles.

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  1. milkism

    Magnetic- and Electric- field lines due to a moving magnetic monopole

    Question: My answer: What it looks like for an electric charge: Am I correct? If you want I can hand out my Latex on how I got to it, it will refer to the book Griffiths a lot.
  2. U

    A Question about dilaton monopole interaction derivation

    I am trying to understand how one derives the dilaton monopole interaction. In "Black holes and membranes in higher-dimensional theories with dilaton fields", Gibbons and Maeda mentioned that one could obtain the dilaton monopole interaction as such: where the action is given by However, I...
  3. A

    B How can a superconductor be used to detect monopoles?

    Why does a monopole detector have to be a superconductor? If there were Monopoles. Why couldn't an EEG machine detect them. Remember in monopoles, moving magnetic charges would generate electric fields. If say the monopole is very strong, it should make the EEG detect them by the probe just...
  4. jordy1113

    I What are the Cosmological monopole and dipole?

    Hi there I'm currently studying cosmology but I'm having a hard time grasping that concept of the cosmological monopole and dipole (quadrupole etc) and was wondering if someone could explain what they are conceptually and physically. Thanks : )
  5. J

    I Valentine Monopole & Detector Constructions

    Here is a high quality article about it written by Ethan Siegel, with Ph.D. astrophysicist, author, and science communicator, who professes physics and astronomy at various colleges and has won numerous awards for science writing since 2008. So it's not a crackpot source. The Enduring Mystery...
  6. LCSphysicist

    About Maxwell's equations and the attempt to insert a magnetic monopole

    I was reading somethings about magnetic monopoles, and how, if it were discovered its existence, it would changes the Maxwell equations, in summarizing, is not the first time i see this: It is the consequences of the existence of a magnetic monopole? That is, IF it exist, SO the imagem is true...
  7. Athenian

    Finding the Monopole and Multipole Moments of the Electric Potential

    My first attempt revolved mostly around the solution method shown in this "site" or PowerPoint: http://physics.gmu.edu/~joe/PHYS685/Topic4.pdf . However, after studying the content and writing down my answer for the monopole moment as equal to ##\sqrt{\frac{1}{4 \pi}} \rho##, I found out the...
  8. dRic2

    Magnetic Monopole: Reason Behind Faraday's Law Counterpart

    For the magnetic fields it is obvious that ##F = q_m B##, but I don't get why the final result is $$\mathbf F = q_m(\mathbf B -\frac 1 {c^2} \mathbf v \times \mathbf E)$$ The second part is like a "counterpart" of Faraday's Law, but I do not understand why it should be there... For what reason...
  9. S

    B Effects of a discovery of the monopole

    I guess i have two questions , is the magnetic field conservative or non-conservative.As far as i can see just looking at a magnetic field we have a curved path hence it wouldn't be conservative, however many textbooks assume it is.Is there something I am not seeing here? Furthermore would...
  10. Philosophaie

    I Stationary Monopole exist at the Origin

    A stationary Monopole exist at the Origin. 1)##\vec{B} = \frac{g \hat r}{4 \pi r^2}## 2)##\vec{E} = \frac{e \hat r}{4 \pi \epsilon_0 r^2}## 3)## - \nabla \times \vec{E} = \frac{\partial \vec B}{c \partial t} + \frac{4 \pi}{c} \vec{J_m}## 4)##\nabla \times \vec{B} = \frac{\partial \vec E}{c...
  11. D

    Current induced in loop as magnetic monopole passes

    Homework Statement Suppose a magnetic monopole q_m passes through a resistanceless loop of wire with self-inductance L. What current is induced in the loop? Homework Equations \nabla \times \textbf{E} = - \mu_0 \textbf{J}_m - \frac{\partial \textbf{B}}{\partial t} \nabla \cdot \textbf{B} =...
  12. B

    Magnetic field strength over distance

    I want to know how does distance affect the magnetic field of a permanent magnet. I have read about the inverse square law and how it could apply to magnetic fields over growing distances, but doing so, I read about monopoles, which is a new concept to me. So, for the time being, I would like a...
  13. quantumgeography

    A Magnetic monopole discovery, but not the creation

    You have probably all heard about magnetic monopoles creation ,but I just want to ask is there theoretical basis (without denying already proven theories) which would allow us to expect natural magnetic monopoles discovery? https://arxiv.org/abs/1607.07460...
  14. I

    A Lagrangian of a monopole (Einstein notation is used)

    Hi everyone, I am trying to calculate the equation of motion of a charged particle in the field of a monopole. The magnetic field of a monopole of strength g is given by: \textbf{B} = g \frac{\textbf{r}}{r^3} And the Lagrangian by: \mathcal{L} = \frac{m\dot{\textbf{r}}^2}{2} +...
  15. DuckAmuck

    Electric Charge Interacting with Magnetic Monopole

    Is there a general solution explicitly worked out for how a monopole and electic charge would interact? Of course the electro-static solution is that there is no interaction, but the electro-dynamic solution would not be so trivial, as moving charges/monopoles would induce magnetic/electic fields.
  16. E

    I Monopole Creation and Higgs Field

    Please consider this statement from Alan Guth (from his book "The Inflationary Universe"). The context is the creation of magnetic monopoles: The monopoles, therefore, are the surviving remnants of the chaos in the Higgs fields immediately after the phase transition. Guth then goes on to...
  17. DuckAmuck

    Is it possible to build a magnetic monopole using permanent magnets?

    Has anyone attempted build a magnetic monopole? If you took a bunch of wedge-shaped permanent magnets and assembled them into a ball such that the same pole for each magnet was pointing out radially, then you would have a magnetic monopole. (see attached).
  18. V

    Has the Charge Quantization Problem Been Solved Without Magnetic Monopoles?

    I am no mathematician, not even an expert in Gauge Theories, but I came across this article http://arxiv.org/abs/1409.6716 (published here http://www.sciencedirect.com/science/article/pii/S0393044015002284) when I was looking for some "condensed-matter-type-monopoles", and the author claims...
  19. A

    Vector potential of the Magnetic monopole

    It is argued here that the use of vector potential to describe the magnetic field of a monopole is inherently wrong http://arxiv.org/ftp/physics/papers/0701/0701232.pdf It will indicate that the affirmation that charge quantization will be proved if a magnetic monopoles exists is wrong. The...
  20. diogenesNY

    How massive is a monopole particle compared to a proton?

    Please forgive the thread title... it just kinda slipped out that way. I am reading and enjoying Alan Guth's _The Inflationary Universe_. Dr. Guth is not only in command of a very lucid style of exposition, but he has a very subtle and penetrating sense of humor. Anyway... He relates a...
  21. Salvador

    Outer monopole generator rotor

    Hello, Happy New Year everyone. I wanted to know or can anybody show me how would a rotor like that look like or how it would be wound? I need the rotors outer part that faces the stator to have a single magnetic pole coming out of it , not like typical rotors that have poles on them and one is...
  22. QuantumCurt

    Writing magnetic monopole analogs for electrical circuits

    Homework Statement This isn't a 'homework' problem as such. I'm currently in University Physics II (E&M), and I've become really interested in magnetic monopoles. They haven't been discussed in any kind of depth in my course, but I'm trying to figure out how a magnetic monopole (if they exist)...
  23. J

    Sound power radiation of dipole and bipole sources

    Homework Statement For a fixed given electrical power to two monopole sources, producing the same frequency. Which mode, either in-phase or out of phase, will radiate the most sound power into the far-field? Homework Equations Is the radiated sound power dependant of the given electrical...
  24. J

    Lagarangian of a charged particle in a magnetic field (magnetic monopole)

    Homework Statement Show that the Lagrangian $$ L = \frac{m}{2}(\dot{r}^2 + r^2\dot{\theta}^2 + r^2\dot{\phi}^2sin^2\theta) - qg\dot{\phi}cos\theta $$ describes the motion of a charged particle (mass ##m## charge ##q##) in the magnetic field ## \vec{B} = g\vec{r}/r^3## (##g## is a constant)...
  25. J

    Forces and fields: magnetic dipole vs electric monopole

    Two electrons, they have their electric fields and magnetic dipole moments. Their electric field is proportional to 1/r^2, and electric force is also proportional to 1/r^2. http://en.wikipedia.org/wiki/Magnetic_dipole%E2%80%93dipole_interaction However, their magnetic dipole field is...
  26. H

    Magnetic Monopole (Magnetic Charge)

    An electric charge produces a Coulomb electric field: E = dqe r/r3 A current element produces a Biot-Savart magnetic field B = i dl×r /r3 From what I understand, magnetic charges are inserted for the sake of making Maxwell's equations symmetric. A magnetic charge is meant to produce a...
  27. K

    't Hooft - Polyakov monopole at large distance

    According to 't Hooft - Polyakov monopole solution, SO(3) is spontaneously broken down to U(1) and the unbroken mode works very well as the electromagnetic field. In this case we do not need dirac string but just some scalar field. At very large distance , the two massive gauge modes can be...
  28. H

    Dirac Expression for Vector Potential of a Magnetic Monopole Problem

    Hi, Homework Statement Consider the vector potential, \vec{A}(\vec{x}), below. The problem is to calculate \vec{A}(\vec{x}) explictly, and show that it has components A_{r}, A_{\theta} and A_{\phi} Homework Equations \vec{A}(\vec{x}) = \frac{g}{4\pi} \int_{-\infty}^{0} \frac{dz'...
  29. Abscissas

    What is the Current Understanding of Monopoles in Physics?

    Homework Statement I am looking for reliable sources with decent information on monopoles, this is a freshman research paper. I am just looking for books websites and any useful information on the topic. thank you Homework Equations The Attempt at a Solution I've gone to the...
  30. A

    Electric field of a magnetic monopole

    A north magnetic monopole moving with uniform velocity through a uniform electric field would experience a force (assume the direction of the force to be upward along the x-axis) due to the circular electric field created around it. Similarly a south magnetic monopole would experience a force...
  31. Spinnor

    Maxwell's Eq, Magnetic Monopoles, GR & Gravimag. Monopole?

    If there was magnetic charge Maxwell's equations could be altered to accommodate the magnetic charge? For small field strength and velocities General Relativity can be put in a form similar to Maxwell's equations? If so is there something that could be introduced into General Relativity...
  32. P

    Show that an oscillating electric monopole does not radiate

    Homework Statement Given \rho(r',t)=\frac{Q}{4\pi (r')^2} \delta(r'-(R_0-\Delta{R}\cos(wt))) J(r',t)=\frac{wQ\cos(wt)}{4\pi r'} , which is an oscillating sphere with uniform charge distribution, find the vector potential, then the magnetic and electric fields. Hint: Integrate in the...
  33. Z

    Let's rename Valentines day and call it Monopole day

    Let's rename Valentines day and call it "Monopole day" In honor of the Valentines Day Monopole of 1982 caught in Blas Cabrera's lab @ Stanford. It was the perfect specimen.And sadly, no other magnetic monopoles have every been found...yet. So happy belated monopole day to everyone here @...
  34. P

    What Is the Spin of a 't Hooft-Polyakov Magnetic Monopole?

    Hi there, I was wondering what is the spin of a magnetic monopole. To be specific, I mean the 't Hooft-Polyakov monopole in the Georgi-Glashow model. Sure, it is a purely classical object and as far as I know, there is no known way how to fully quantize it. So, strictly speaking, the notion...
  35. L

    Does macroscopic magnetic monopole contradict physics?

    I know Dirac had said yes to existence of microscopic monopole by quantum theory, so why not the macroscopic monopole?
  36. Y

    Laplace-Runge-Lenz Vector for Magnetic Monopole

    This is related to Goldstein Exercise 3-28. It is not really a homework problem anymore because I have solved them. But there's something bugging me so I shall post here instead of under homework problem. The Exercise reads: A magnetic monopole has magnetic monopole B = br/r^3 where b is a...
  37. G

    Would one consider the following to be a monopole, or a dipole?

    I hope that I have chosen the correct thread and that this belongs here. I understand the concept of a dipole, where you have opposite polarities at each end of a lineal object, i.e. a magnet. My question concerns the case of a sphere, where the outer surface is one polarity and the center is...
  38. C

    E & B Fields from Moving Charges: The Magnetic Monopole Mystery

    Lets say I have a negative line charge on a long thin rod, if I am at rest with respect to that rod I will see an E field. But If I am moving with respect to that rod I will see a B field. So why are people looking for magnetic monopoles, If B fields are E fields in disguise, wouldn't the...
  39. D

    What will happen if I assemble magnets with flush joints and the same polarity?

    I cut some magnets into buckeyball-faced polyhedra and bond the pieces together so that all joints are completely flush. Assume the joints are perfectly planar-flush, and bonded with a monolayer of something with a small molecular size. Or better yet, the thing is assembled in a vacuum and the...
  40. D

    Monopole crystal radio antenna length

    Good Morning Can anyone help me understand why, apparently the physical length of a monopole end feed wire for a crystal set need to be ½ the wave length of the desired signal. The reason I ask is, that I understood that, if you have a variable coil in series with the antenna, the...
  41. W

    Anyone solved eigenstates in the field of a magnetic monopole?

    any references? i think it is a basic problem
  42. H

    What is the nature of radiation from an oscillating electric monopole?

    From another Physicsforums thread I found this outstanding webpage: http://www.lightandmatter.com/html_books/genrel/ch09/ch09.html" which contains this startling statement: Suppose you place a highly charged ball in space and oscillate it with an insulating piston connected to a simple...
  43. R

    Magnetic Monopole: Properties & Detection

    Hello, First I would like to introduce a brief definition of such a particle from Wikipedia: Now, my question is how would magnetic monopoles be detected? Does anyone of you know about more properties of these particles for a better understanding?
  44. F

    Is There Solid Evidence of Magnetic Monopoles?

    Homework Statement To find magnetic monopole. Homework Equations I need to know whether or not there is The Attempt at a Solution I have searched around and i can't see to find any SOLID evidence p.s. I am so sorry if this the wrong forum. I am a newbie.
  45. S

    Do gravitons spiral around a monopole?

    I'm a sci-fi writer and would like some help, if you would please. My story is simple: monopoles arising in spin-ice can be charged with enough magnetricity to deflect spin 2 gravitons, freeing manking from the tyranny of a lone world, and propelling us into a vast new tyranny. I heard...
  46. mg0stisha

    Magnetic Monopole: Exploring a Possibility

    We were having a discussion about magnetic monopoles in an AP Physics course a while back, talking about why they can't happen, etc. One of the other students (there were 7 of us, haha) said, "What if you magnetize a bunch of needles and then stick, say, all of the south poles into a styrofoam...
  47. P

    Lagrangian of a Force Law, with magnetic monopole

    We know the covariant Lagrangian of the Lorentz force law. However, in presence of a magnetic monopole, one must add another term to the force law. This term, of course is the Dual Field Tensor, along with the magnetic charge 'g' as follows - m \frac{d^2 x^{\mu}}{d {\tau}^2} =...