Researchers have discovered magnetic monopole quasi-particles
cam.ac.uk
cam.ac.uk
The title is basically clickbait and personally it triggers a collective truma of hundreds who worked on that during the last 7 decades. Well we might actually have discovered a magnetic monopole in the 80s on the famous valentine's day experiment/incident. [1]
As many people here mentioned, these are not the groundbreaking and fundamental particles that we call magnetic monopole that was predicted by Dirac or GUT monopole (predicted by many grand unification theories). This manifestation of spin effects is consistent with the unsymmetric Maxwell's equations we have and wouldn't prompt a modification like if we discovered the "fundamental" magnetic monopole. Well thanks to inflation, we probably never going to be able to see it even it exists. [2]
Probably titles like these are part of the reason why HEP physicists have their own APS conference (april) and don't participate in the more generic march conference /S.
[1]https://www.nature.com/articles/429010a
[2] https://en.m.wikipedia.org/wiki/Big_Bang#Magnetic_monopoles
It's moving information faster than the speed of light that's tricky.
The Standard Model is a theory that describes the fundamental particles and forces (except gravity) in the universe. It is essentially a set of mathematical equations that explain how particles like quarks and leptons (i.e electrons) interact through forces mediated by particles like photons (for electromagnetic force), W and Z bosons (for weak nuclear force), and gluons (for strong nuclear force). These interactions are described using quantum field theory, which combines quantum mechanics (dealing with the smallest scales of energy levels and particles) with special relativity (dealing with particles moving at high speeds).
Now, regarding magnetic monopoles, these are hypothetical particles proposed in various theories. There are two main types of hypothetical magnetic monopoles that theorists have considered:
- Dirac Monopoles: Proposed by Dirac in 1929, these monopoles are simpler and would arise from modifications to electromagnetism. Dirac showed that if magnetic monopoles exist, they would explain why electric charge is quantized (i.e., why it comes in discrete amounts like the charge of an electron). However, Dirac monopoles don't fit neatly into the Standard Model as it currently stands. They would require some extension or modification of the model.
- Grand Unified Theory (GUT) Monopoles: These are more complex and emerge from grand unified theories, which are theoretical frameworks that attempt to unify the gravity, electromagnetic, weak, and strong forces into a single force. In these theories, monopoles are heavy and rare relics from the early universe, a time when the fundamental forces were unified. In many GUTs, conditions in the early universe would have allowed for the creation of magnetic monopoles. These monopoles are predicted to be very massive and thus difficult to produce and detect with current technology (LHC energies are still too low to produce them).
So as of now, there is no experimental evidence for magnetic monopoles (this did not change by this announcement). Their theoretical existence is a topic of significant interest, but it remains speculative and outside the direct scope of the Standard Model. Any confirmation of magnetic monopoles would be groundbreaking, potentially opening up new physics beyond the Standard Model.
Probably Biden's fault.
They’re not “real” monopoles, in the sense of individual particles that generate a divergent field but rather a quasi-particle (the collective behavior of many individual atoms producing this overall effect).
In the worlds of the authors:
“These monopoles are a collective state of many spins that twirl around a singularity rather than a single fixed particle, so they emerge through many-body interactions. The result is a tiny, localised stable particle with diverging magnetic field coming out of it,” said co-first author Dr Hariom Jani, from the University of Oxford.
That being said, the applications are still pretty exciting and this is something that many people wouldn’t have tought possible at all.
This is equivalent to propping up a horseshoe magnet with the ends up, and laying a piece of paper across it; that also gives you a 2d surface with a pair of monopoles on it.
It's still interesting and probably useful for building things, but it's not "we broke a known law of physics".
Is that what the paper is suggesting? I didn't see that, but admittedly most of it went over my head.
Can this be replicated on the macro scale with meta materials?
What are the actual uses?
I can't get the article to load, if that's in there.
> Using muon spin rotation as a suitable local probe, we apply the method to a real material, the ‘spin ice’ Dy2Ti2O7 (refs 5–8). Our experimental measurements prove that magnetic charges exist in this material, interact via a Coulomb potential, and have measurable currents.
This new paper points out how these monopoles are different, at https://www.nature.com/articles/s41563-023-01737-4
> The reported duality between magnetic charges and topological AFM textures sheds light on a new class of materials hosting 2D monopolar physics in contrast with other systems that harbour emergent magnetic monopoles, such as the pyrochlore spin ice. Although intriguing, monopoles in spin ice are intrinsically distinct, as they have an underlying gauge charge, which is topological and quantized. Conversely, the emergent magnetic charges in haematite are 2D, not quantized and are topological in the sense that they dress topological AFM textures underpinning them.
These monopoles are a collective state of many spins that twirl around a singularity rather than a single fixed particle, so they emerge through many-body interactions. The result is a tiny, localised stable particle with diverging magnetic field coming out of it,"""
So do I take it that there is some kind of superposition of spins that locally, possibly just in a 2D cross section, appears to have a magnetic field with non-zero divergence? Is \nabla\cdot\vec{B} actually violated somewhere? The language seems pretty cagey.
Incidentally, I belive Dirac posited that they existence of magnetic monopoles would explain the quantization of charge.
In the "Emergent Magnetic Charge" section, second paragraph:
"Finally, we emphasize that the observation of emergent monopoles is fully consistent with the modelling of AFM topological textures in Fig. 2 and does not violate Maxwell’s equation as they are, in fact, sinks and sources of the H^ field."
So this is a collective effect of a bunch of magnetic dipoles, and they go on to describe how div B is indeed zero in the material.
So this is not a Maxwell's Equations violation or anything, it's just some 'trick' to make a field that somehow locally looks divergent.
Please correct my understanding if you know better and I'm wrong.
"Nick Sohl was coming home.
...He had gone mining in Saturn's rings, with a singleship around him and a shovel in his hand (for the magnets used to pull monopoles from asteroidal iron did look remarkably like shovels)...
A century ago monopoles had been mere theory and conflicting theory at that. Magnetic theory said that a north magnetic pole could not exist apart from a south magnetic pole, and vice-versa. Quantum theory implied that they might exist independently.
The first permanent settlements had been blooming among the biggest Belt asteroids when an exploring team found monopoles scattered through the nickel-iron core of an asteroid. Today they were not theory, but a thriving Belt industry. A magnetic field generated by monopoles acts in an inverse linear relationship rather than an inverse-square. In practical terms, a monopole-based motor or instrument will reach much further. Monopoles were valuable where weight was a factor, and in the Belt weight was always a factor. But monopole mining was still a one man operation.
Nick's luck had been poor. Saturn's rings were not a good region for monopoles anyway; too much ice, too little metal. The electromagnetic field around his cargo box probably held no more than two full shovelfuls of north magnetic pole. Not much of a catch for a couple weeks backbreaking labor... but still worth good money at Ceres."
Some more discussion: https://news.ycombinator.com/item?id=38548002
In other words, should we expect that this discovery (and the apparently previously discovered monopole quasiparticles) have the exact same use and application as a hypothetical normal particle monopole?
"Finally, we emphasize that the observation of emergent monopoles is fully consistent with the modelling of AFM topological textures in Fig. 2 and does not violate Maxwell’s equation as they are, in fact, sinks and sources of the H^ field."
So this is a collective effect of a bunch of magnetic dipoles, and they go on to describe how div B is indeed zero in the material.
I couldn't find a mention of the flux, but I suppose it could be covered there and I just missed it.
Discovering true magnetic monopoly would be biggest discovery in physics since ____. Gauss's law of magnetism violated. This was not it.
This is not less interesting because it's "just a quasi-particle".
This is 2d surface behavior of a solid material. The magnetic fields on the 2d surface act as if there are mobile particles with magnetic charge moving around on the surface.
1. No new particles for starters.
2. This is not first time magnetic monopoly quasiparticles have been discovered in materials. Mangetic monopoles have been discovered in materials in the past https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.10..., https://www.nature.com/articles/news.2009.881
-Quasiparticles: We select some property by drawing a box around a set of adjacent particles and computing over those particles. That property is not represented in a single and unattached member of that box. It isn't the real thing but might approximate some nifty functions you wanted if scaled up and embedded in the right material under the correct circumstances.
-"...in a simulation": This means that this is only as good as your programming (and databases and libraries) is, on top of how well that programming relates to the math you think represents the system in question. Not only do you not have the real thing, you have bits representing the answer to your imperfect programming based on what you think the math is (and what math can be ignored) in your model.
-Analogue of in another system: See sonic black holes. Parallels are drawn between math in one system and math is an entirely different system. Some expect that new inferences can be drawn from the comparison, but you still don't have the real thing, you have a cardboard box with subdividers and you wonder how that applies to high-rises.
-Property exists in n-dimensions: Where N is not our three spatial dimensions. It's not the real thing because we don't have anything with just two spatial dimensions, or an extra spatial dimension, but maybe, just maybe, that can lead to some interesting properties on the edge of the thing, or its face, but probably not in the way you would expect.
Listen for their hooves during any breathless science press release about physics, materials science, and so on.
This position entails climate denialism. Do you?
The raw data shows no warming trend. NOAA and NASA admit this, it’s not a conspiracy theory. The adjustments made that show warming are based on models. Hence to trust the warming trend you have to trust the models, which are very computer simulations.
seems like some sort of virtual or model-like result based on emergen properties
If the existence of magnetic field is unnecessary, there is no reason to even search for a magnetic monopole.
I appreciate the context on "monopoles" in this thread. Can anyone help me wrap my head around quadrupoles?
Essentially, it's a configuration of 2 south poles and 2 north poles. It's pretty important if you're doing quantitative magnetism. Many magnetic configurations don't generate a pure dipole-like field, but also need higher order contributions - like quadrupole and octopole moment - if you want to model/calculate the field.
Quadrupoles also have useful technical properties, you can use one to re-focus the beam in a particle accelerator, for example. In a sense, they act like magnetic lenses.
Or, maybe that's not even a reasonable mental model / distinction - magnetics be freaky.
The interior hollow. The shell comprised of bar magnets with all the PLUS pointed inward and the MINUS pointed outward.
That would be like a MINUS MONOPOLE.
Yes no maybe?