The Electromagnetic Force of Fridge Magnets

https://nautil.us/issue/104/harmony/the-electromagnetic-force-of-fridge-magnets

by dnetesn • 5 years ago

77 21 5 years ago

BenjiWiebe• 5 years ago

According to https://www.theguardian.com/science/blog/2010/jun/09/science..., the rising action of cake is mostly from water boiling and leavening agents producing CO2: "Carbon dioxide and water vapour account for approximately 90% of the subsequent expansion of the batter, the remaining 10% being due to thermal expansion."

gerdesj2• 5 years ago

Tell that to my mother! She was an absolutely belting cook but always ended up with a caldera in her sponge cakes.

She was able to make clotted cream from first principles - she was Devonian. She also introduced pasties to several parts of West Germany in the 1970s/80s. The food traffic went both ways in Germany and I have a massive fondness for schnitzels - "Zigeuner" (gipsy, I think) and "Jager" (hunter - deffo).

Mum was also a soldier as well as dad (they were both Captains when they met in Scotland) but she was told to get out what with her being a woman and hanging out with a male Army occifer. That was back in the late 1960s. Times have changed a lot since then.

Anyway, cakes. mmmm cakes.

emmelaich• 5 years ago

Caldera you say?

Some cheeky person has put Penn and Teller's recipe up on epicurious ...

https://www.epicurious.com/recipes/member/views/swedish-lemo...

gerdesj2• 5 years ago

The OP is a lovely work and beautifully illustrated.

I recently spent 18 months working from our dining room table. I regularly have to worry about swapping out broken hard discs in my work data centre. I took a 3.5" SMART failed SAS drive apart fairly recently and turned the two magnets into fridge magnets. My wife cannot physically pull them off (ooerr missus) the fridge directly. She has to slide them to an edge or use a lever.

The grandkids' latest artistic efforts stay stuck to the fridge and so do appointment cards etc. My step-mum grabbed at one of those because she thought it was falling off and the door opened instead and then the painting ripped. Calamity! We got the little darling to do a copy and great granny calmed down a bit.

It's a shame that more people aren't commenting on this page. It is lovely.

duffyjp• 5 years ago

I use hard drive magnets as key hooks. Keys themselves don't stick, but the keyring does and holds great. I put my business card under mine and the wife's under hers both to label and to have a way to eventually remove them from the fridge.

I also superglued two to a pair of old Xeon CPUs that look really cool and have enough lip to be easily removed. They make ideal fridge magnets!

amelius• 5 years ago

It's a shame that more people aren't commenting on this page. It is lovely.

The illustrations are nice, but they often make so little sense: the topic is mostly about molecular interactions, yet the illustrations show macroscopic scenery. Also, the entire article reads like a grab-bag of Wikipedia entries, and only the first paragraph of each entry. I thought this was going to be an in-depth article about magnets! Furthermore, the entire page including the text is an image, which is not how the web is supposed to work.

CamperBob22• 5 years ago

Also, their induction hob appears to be on fire.

Fezzik2• 5 years ago

You reminded me of an old trick (now expired) that my grandma taught me: take the magnet out of used Sonicare toothbrush heads, wrap the magnet in electrical tape creating a pull-tab, and you have a rather powerful refrigerator magnet! Sonicare removed the original magnet vibrating mechanism quite a while ago so this no longer works, but I love creative reuses like this for items.

mkmk• 5 years ago

How do they vibrate, then?

ta988• 5 years ago

Warm them a little and you can make them weaker. you have to be gentle though. Edit: Curie temperature of neodymium magnets is 320°C so "a little is relative".

aidenn0• 5 years ago

A friend of mine used to work at Western Digital. He had a magnet from a 10k RPM SCSI drive on his cubicle. If you tried to lift it straight off rather than pry it, you would just lift the cubicle.

kragen3• 5 years ago

Typically fridge magnets are made of ferrite, which is ferrimagnetic, not ferromagnetic, as has been known since 01948; though, if you recycle some hard-disk voice-coil magnets, you will have truly ferromagnetic fridge magnets.

And this illustrates a problem with all of these explanations: none of them is precise enough to yield falsifiable predictions. (The fact that this one is wrong is, by comparison, minor. Incorrect reasoning from evidence can be corrected. Erroneous observations can be corrected with correct observations. But vague explanations can always be lawyered to fit the evidence.) Although these explanations are written with scientific words, they are not scientific explanations; they belong to the same genre as Kipling's Just So Stories or quantum-healing pseudoscience.

Or, in some cases, Life Hacks: if you drip drops of water on your "hob" and they just sit there because it's an induction "hob", you've at least empirically validated that you don't see the Leidenfrost effect. (Let's hope you know how to reseason your cast-iron skillet after you successfully reproduce the Leidenfrost effect on that.) But you'll never be able to falsify the Leidenfrost effect working from this bullshit picture, because it could always just be that your "hob" isn't hot enough; to have a falsifiable prediction, you'd need to know that water's Leidenfrost point is 193°C normally, but can be as high as 210° or as low as 150° depending on circumstances. If you have your skillet at 250° and water drops are still not floating around in a spooky way, you have falsified the prediction. (The text, "When a liquid is on a surface hotter than its boiling point, drops float on a layer of vapor," could be read as claiming that the Leidenfrost point is the same temperature as the boiling point, which is wrong.)

Science is what comes with a demonstration.

How would you tell, for example, if your cake is frothing up because of Charles's Law, because water is vaporizing, because dissolved gas is coming out of solution, because baking soda is being decomposed by heat, or because baking soda is being neutralized by an acid? How would you tell if your saliva is missing amylase, or your bread is missing starch? It's possible to do it, but you need more than a Just So Story that says "fluffy texture" or "aids digestion".

What's worse is the kind of "science" classes that consist of memorizing and regurgitating this kind of discourse; essentially the exams are testing your ability to memorize (or guess) the teacher's password, reducing science to the level of slogan-shouting politics. Feynman had a wonderful story about how this disease had taken over the Brazilian university system, to the point that his physics students were surprised that sunlight reflected off the ocean was polarized.

I think this kind of "science" popularization is to blame for the rise of quantum healing and the like (not to mention the devastation of the curent pandemic, as I sort of argue in https://news.ycombinator.com/item?id=28332889). Once you remove the evidence and empirical grounding from a scientific explanation, you can't expect the vulgar to magically intuit that the evidence is really there, behind the scenes; they won't be able to tell the difference from Deepak Chopra bullshit.

Because the difference is the part that's been intentionally left out.

CamperBob22• 5 years ago

Some very worthwhile points there, but I think you may be underestimating the challenges of how to introduce these topics to an audience that may never have encountered them before. Rigor certainly has its place, but an article like this isn't it. It's clearly meant to be a jumping-off point, nothing more.

kragen3• 5 years ago

I certainly don't mean to imply that learning science is easy, and teaching it is even harder. And it's of course necessary to have some kind of index so that you can figure out what effects are relevant to the physical phenomenon you're interested in, whether that's fridge magnets, towel absorption, sugar dissolution, opacity and transparency, or firework colors, so that you can go do some scholarship on what is already known about those effects.

A jumping-off point, however, would need to have links to further information. If you're interested in fridge magnets, you'll want to know not only about the ferromagnetism of the refrigerator but also the ferrimagnetism of the magnets, Halbach arrays, and magnetic field viewing film (or at least iron filings on paper). If you want to make fridge magnets, as opposed to just gluing them to things, you'll probably want to know about filled composite polymer systems (which are why you can cut fridge magnets with scissors), permeability, degaussing, coercivity, saturation remanence, and the Curie temperature. Making fridge magnets would probably give you deep enough knowledge to know that the theory isn't total Deepak Chopra bullshit, but maybe not enough to be able to measure saturation remanence and permeability.

But the key and principal point here is that science is not a body of facts like the coercivity of strontium ferrite. Science is a way of finding things out, and that way is precisely the opposite extreme from accepting without question what a magazine article says, even if it uses scientific words like, "Permanent magnets, working through ferromagnetism, have tiny crystals in their structure aligned so their magnetic fields add together. Fridge magnets incorporate small ferromagnets that enable them to attach to the metal fridge." The scientific or philosophical approach instead is to question those assertions to within an inch of their life, establishing reliable knowledge through reasoning and empirical evidence instead of accepting authoritative opinions as fact. (In this case, the authoritative opinions pack an astounding number of errors into only two sentences: fridge magnets are typically ferrimagnetic rather than ferromagnetic, it is not sufficient for the fridge to be metal, and magnetic domains are not crystals.)

And that's what it's most important to teach: not the particular facts that have been found so far, but the practice of questioning authority and reasoning critically based on empirical evidence. I mean, scholarship is nice, but it won't debunk the phlogiston or tell you that there are more than four elements, unless somebody's already done that for you. Even then, it's hit or miss: scholarship can just as easily lead you to believe popular pseudosciences like astrology, or worse, formerly popular pseudosciences like racism.

How would you create a jumping-off point for debunking mistaken authoritative statements with reasoning and empirical evidence? This article could barely be farther from being such a thing. I mean, it's full of mistaken authoritative statements, but that only helps the tiny minority of readers who debunk them! Maybe something like The Skeptical Inquirer or some practice in motorcycle maintenance, for example?

To some extent, though, reading material is crippled in its ability to teach people to investigate things scientifically instead of from reading material, because the medium undermines the message. "Atheist" communities, for example, seem to fall into the trap of just accepting different authoritative statements as fact; witness, for example, jhgb's embarrassing inability in https://news.ycombinator.com/item?id=28337805 to understand that mercury distillation was pioneered by ayurvedic doctors, because they class ayurveda as "pseudoscience", which of course it is.

irrational• 5 years ago

For anyone else who didn’t know, a hob is the British word for the top of a stove (the stovetop). Though, according to 2 dictionaries I checked, it more usually means hobgoblin in British English. I wonder if they have puns about these two meanings.

kragen3• 5 years ago

I was thinking maybe they shared a common origin, but apparently not: https://www.etymonline.com/word/hob

I think speaking of stovetops is around two orders of magnitude more common than speaking of hobgoblins among BrE-speakers nowadays.

PaulDavisThe1st• 5 years ago

birth BrE here, 32 years of AmE ... never ever heard "hob" as related to "hobgoblin".

_Microft• 5 years ago

The article is nice but the title could be better.

I, for one, expected the content to be about Halbach arrays. This is a particular way of arranging magnets that increases the magnetic field on one side of the array while decreasing it on the other.

It is often used for fridge magnets.

https://en.wikipedia.org/wiki/Halbach_array

The Electromagnetic Force of Fridge Magnets

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