as everyone knows there are three different types of magnetism so I was a bit surprised to learn of a new third type of magnetism didn't we already have three what's new I had a look the magnets that we all know and like are what physicist call ferromagnets materials with these properties include most famously iron which the name ferromagnet derives from as well as nickel Cobalt and many Alloys when it comes to the Alloys it's apparent already just one why magnetism is so confusing take steel as
an example depending on the crystal structure and Fabrication some types of Steel are magnetic others not and some are magnetic in some places though none of them will stick to your forehead after vaccination contrary to popular belief magnets also don't stop working if you put them into water all I know about magnets is this give me a glass of water let me drop it on the magnets that's the end of the magnets though I'm sure what Trump had in mind there was elect magnets which I indeed recommen
d you don't throw into water or if you do at least don't sit in the water at the same time where does magnetism come from Magic well the electromagnetic interaction is one of the fundamental forces of nature it doesn't come from anything at least not that we know it's rather that other things come from it for example fridge magnets or as Richard Fineman put it so I'm not going to be able to give you an answer to why magnets attract each other except to tell you that they do but we can understand
to some extent how magnetism and materials comes about from this fundamental magnetic force it's that atoms all have electrons hovering around them and that makes each atom a tiny little magnet where the strength depends on the type of atom the question is then how these individual magnets combine in materials in ferromagnets what happens is that the magnetic moments of neighbor ing atoms like to align and they hold on to this alignment this is why you can magnetize these materials in most mate
rials that doesn't work because the orientation of the tiny Atomic magnets won't stay aligned with the neighbors but even ferromagnetic materials will lose their magnetization if you heat them up too much that's because then the atoms Shake around too much basically so maybe Trump was speaking of boiling water I'm sure that's what you must have meant in any case that's pherom magnetism which most of you will be familiar with the second kind of magnetism is called di magnetism di magnetic substan
ces react to magnetic fields by weakly repelling them an interesting example of a DI magnetic substance is water you can see this in this little demonstration in which the magnet seems to attract the air bubble though actually it repels the water diamagnetism had its moment in the Sun when a group of scientists demonstrated it by making a frog levitate since humans like frogs are basically big backs of water I suppose you could levitate humans the same way if only the magnetic field was strong e
nough you know I think if CERN said they want to build a magnet strong enough to levitate humans I'm pretty sure they'd have an easier time getting money so we have pherom magnetism and diamagnetism and then there's paramagnetism paramagnetism is similar to diamagnetism in that it's a response to a magnetic field but paramagnets are attracted to rather than repelled by the magnetic field some paramagnetic materials are oxygen aluminium and platinum that makes paramagnetism diamagnetism and param
agnetism by my count that's three and then I read this press release which says that a group of experimentalists in Switzerland has experimentally proved a third branch of magnetism termed alter magnetism all right but we already have three right I read the paper and they count ferromagnetism anti ferromagnetism and alter magnetism oh dear but don't despair we can sort it out remember that in a ferromagnet the atomic magnets react strongly to each other and they like to align in an antiferromagn
etic material they also react strongly to each other but they don't want to align so you get a mix of one and the opposite direction this happens for example in chromium an antiferromagnetic material then has no total magnetization and won't hold stuff to your fridge but they're good at holding orientations of the tiny magnets which is why they're used in Computing for storage and for other things the alter magnetism now is a new type of magnetism in which the directions of the atomic magnets al
ter in periodic configurations creating a local polarization of the field but no total magnetization so these Auto magnets might appear to be antiferromagnetic but the point is that they have these interesting stable structures in the polarization what they did in the new papers is that they confirmed for the first time that some types of crystals actually have this Auto magnetism it's been there all along basically it's just that no one knew it existed why is this interesting well first of all
it's fascinating that they discovered a completely new class of materials and it's not even stuff that needs to be synthesized in a complicated way one of the compounds they used is ruthenium oxide which is maybe not exactly on your friend list but popular enough to have a Wikipedia page and be available for order online but besides the general interest these Auto magnets might be useful because their alternating patterns can be used to encode and transport information and that could be handy fo
r electronics maybe even for Quantum Computing and just just in case you thought you understood it there's a thing called fery magnetism did you know I have a quantum mechanics course on brilliant.org it's a beginner's course that you can take without any background knowledge it'll introduce you to topics such as interference superpositions and entanglement the uncertainty principle and B theorem and afterwards you can continue learning more about your favorite topics in science computer science
or maths all courses on brilliant come with interactive visualizations and follow-up questions it's really an easy and fun way to learn something new if you want to try it out for free use our link brilliant.org Saina first 30 days are free and the first 200 of you to use this link will get 20% off the annual premium subscription thanks for watching see you tomorrow
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Magnets are great for getting children interested in physics. Interestingly, those who are very much attracted by magnets often remain child , throughout puberty and adolescence and build larger particle accelerators.π
To resolve some of the confusion, the term "magnetism" is used in essentially two different ways: (i) to classify how a material reacts to an externally applied magnetic field and (ii) spontaneous magnetic ordering (symmetry breaking). As for (i) there is indeed mainly paramagnetism, diamagnetism, and ferromagnetism. Now comes the confusing part: while paramagnetism and diamagnetism are quite easily understood and explained in elementary textbooks (Pauli spin paramagnetism and Landau orbital diamagnetism), already ferromagnetism is much more complicated and belongs to class (ii) of spontaneously symmetry-broken phases of matter. Most condensed matter physicists don't think of para- and diamagnetism as "magnetism" but only think of (ii) -- and now there are many different types of magnetic ordering indeed. The main ones are (1) ferro and (ii) antiferro, hence the use of "third" type of magnetic order for altermagnetism. But then there is ferrimagnetism (essentially a version of antiferro...) but also spin spirals, multiferroics (magnetism intertwined with ferroelectric ordering), and an entire zoo of more exotic magnetic orders. So, yeah, as always, it's complicated (and rich and very interesting). :)
My daughter had to do a science project for class about 15 years ago. Being a science loving dad, I found a cool kit using bismuth and neodymium magnets to demonstrate diamagnetic levitation. I had to construct a small plat form to be able to adjust the distance between the diamagnetic bismuth and the little magnet cube to achieve the necessary balance between attraction and repulsion, but it was successful, and earned my daughter an A grade. I used the same kit two years later when my son had to do the same project. Again, it was a success. I taught my kids how it worked, but they wrote their own papers explaining how it worked. Magnetic levitation makes for a great science project!
There are lots more "magnetisms":Β β’ helimagnets (magnetic moments arrange themselves into helical repeating patterns) β’ ferrimagnets (mentioned at the end, in which moments are antiferromagnetically coupled, but because there are at least two different kinds of magnetic ions, the net magnetization for a macroscopic sample isn't zero because the moment cancelation of the moments isn't complete) β’ Pauli paramagnetism (the small net magnetism in a metal's conduction electrons induced by an applied magnetic field - 'up-spin' and 'down-spin' conduction electron populations are slightly imbalanced) ... and many more complicated and more arcane things In short, the textbooks are already full of many of these ... it's very doubtful that this 'altermagnetism' will lead to revisions - and it isn't even clear that this is really phenomenologically distinct from existing stuff.
I've had a terrible day at work today but watching that frog fly has cheered me up a lot. Thanks for sharing!
1:15 So literately magic.
I love your explanation about where magnetism comes from: MAGIC!
4:05 This still makes no sense because the third entry in this list should be Ferrimagnetism. So depending on how you count, Altermagnetism, would either be the fourth, the fourth or the sixth type of magnetism.
Just a couple years ago I was trying to pick up a coil of copper with a ferro magnet and I was perplexed that it didn't work. I had been working with electricity and magnetism for decades and somehow I didn't know that copper wasn't magnetic.
Electromagnets work perfectly fine under water if you dunk them in waterproof resin/enamel, pull a vacuum to get most of the air out, then cure under pressure to crush remaining air bubbles while the excess drips off. Or just put them inside a plastic housing, flood that with sealant and then use magnetic coupling to move the pump impeller like many submersible pumps do.
Every material is at least diamagnetic. There can be stronger collective ordering such as ferromagnetism on top, but if you take the bare elements they are always diamagnetic. It's something like a Lorentz rule back action argument from the electron movement within the magnetic field. By the way, would be great to see a video on "Magnonics", which is the research field that is actually dedicated to using magnets (spin-waves) for information processing!
One of the best science channels around! Always on the forefront! Hervorragende Arbeit, Frau Hossenfelder!
So basically, I counted 6 types
Maybe Trump was talking about MAGAnetism... I'll see myself out.
I am fan of you. You explain even complex topics in very interesting and simple way. You explain latest inventions and research in the field of physics very well.
I was a Scout as a kid, and I had a Silva hiking compass. When I graduated from high school I put it in one of those metal cookie tins, along with a bunch of other junk, and didn't open the tin for twenty years. When I did it pointed south. Or, rather, it pointed south if I tilted the base of the compass so the needle would swing freely. Compass needles align with the Earth's magnetic field, which is not parallel to the surface of the Earth. In the northern hemisphere needles would point north and down, except that the needle is weighted on the south end to make it level. With the magnetism of the needle swapped, the counterweight was working against the tilt, not with it. After a couple of months of being outside the tin, the magnetism switched, again, and the needle started pointing north. I have no idea what was the cause, though I suspect the tin was acting as a Faraday cage.
Donald Trump is a well known expert in fields concerning repulsive forces.
Fascinating! Thanks a bunch, Sabine! π Stay safe there with your family! ππ
Time to redo the maps! Whatβs just around the corner will be huge, love and light
Your humour as always, flawless! How I laughed! π