Monday, December 24, 2018

Magnets: No, But Seriously, How DO They Work?

In 2010 we saw a collision of two forces that, together, generated a series of memes that are referenced even to this day.

Those two forces were the Insane Clown Posse, and Troll Science.

For those who have no idea what I'm talking about, let me give some history.  The Insane Clown Posse is not so much a "posse" as a "duo."  It includes two hip-hop artists named Violent J and Shaggy 2 Dope.  (Both of whom are legally named Joseph.)  In 2010 they came out with a song called "Miracles" that is about the wonder of the world around us.  Unfortunately, because the two Josephs aren't especially educated, their list of wonders included " everything chilling underwater... hot lava, snow, rain and fog, long neck giraffes," and an anecdote about feeding a pelican a fish and nearly having their cell phones stolen by the pelican.

Perhaps the most quotable part of an otherwise unremarkable and mediocre song was the question "Fuckin' magnets: how do they work?"  People began quoting this, mocking the child-like innocence of such a basic question.

Sometime in 2010, someone on 4chan came up with an idea for "troll physics" or "troll science," which involved coming up with poorly-drawn schematics for impossible inventions.  Troll science relied heavily on magnets, probably because magnets are not well understood.

And here's where the Insane Clown Posse got it right.  No one really gets magnets.  Everyone laughed at ICP for asking how magnets work, but let me challenge you, reader.  Right now, without cheating, without looking it up... do you know how magnets work, or even what a magnet is?

Today's post is all about explaining how magnets work.

Not like this.

A magnet is any object that has a magnetic field, and a magnetic field is the interaction of magnetic items and electrical currents. Magnetism, like electricity, is the result of a field of polarized particles, and magnetic attractions and repulsions are a result of electron interactions on an atomic level.  Magnets attract each other because they exchange both electrons (charged particles) and photons, or the particles that make up light. 

Both electrical fields and magnetic fields involve the sharing of charged particles between molecules.  This is why you often see "electromagnetism" smashed into a single fundamental principle; together, magnetic fields and electric fields comprise electromagnetism, which, you might remember from physics class, is one of the four fundamental forces of nature, along with 1) hot lava, 2) snow, rain, and fog, and 3) long-necked giraffes.

No, seriously, it's electromagnetism, strong nuclear forces, weak nuclear forces, and gravity.  There also might be a mysterious Fifth Force.  Fifth Force could easily be an indie band, an action movie franchise, or a questionably racist social group.  But currently it refers to theoretical interactions involving our favorite up-and-coming subatomic particle, the boson.  In defense of the Insane Clown Posse, "boson" doesn't rhyme with as many things as "magnets."  (Then again, they opted to use the word "giraffe."  And while "giraffe" rhymes with such words as "carafe" and "lithograph," I question whether the ICP would know those particular words.)

Back to magnets!  When you think of magnets, you probably imagine a permanent magnet, which is any magnetized item that creates its own magnetic field.  There are plenty of metals that are ferromagetic (meaning that they can be magnetized and that magnets affect them): iron, obviously, but also nickel and cobolt.

Actually, everything is magnetic.  There are four types of magnetism, shown in the chart above.  When we say "magnetic" we're usually talking about ferromagnets but all substances are magnetic.  After all, magnetism simply describes the interactions of charged particles, and all molecules have charged particles within them.  But iron, cobolt, and nickel have the most interesting and dramatic effects and so when a person says "magnet" you probably think of something that interacts with these metals in particular.  After all, we can't see magnetic fields.  We can only observe the effects of ferromagnets, or the colors of a periodic chart we found in a Google search while writing a blog post.

(If you, like me, looked at the chart and immediately noticed that chromium is special, and wondered what "antiferromagetic" is, the answer is simple.  Except, like magnets, no, it's not.  Looking at the above chart, I thought perhaps chromium was something that demagnetized magnets, in the way a magnet can ruin your credit card.  But it turns out that being antiferromagnetic is a ridiculously simple term to describe a ridiculously complex atomic state in which the spin of the electrons of the chromium molecule aligns in a flip-flopping patterns with other neighboring electrons.  So it's just another type of magnetism. Any item with unpaired electrons is a magnet... the question we humans are concerned with is, can we stick it to the fridge?)

Long before humans knew what fridges or electrons were, or could even conceive of them, we knew about magnets.  It should come as little surprise to you that the ancient Greeks are one of the earliest civilizations to describe and wonder about magnets.  Naturally occurring magnets found in the ground were called "Magnesian stones."  Magnesian stones (magnētis lithos) were also called "lodestones."  Lodestones are clumps of the mineral magnetite, which is one of many types of oxidized iron ores.  Magnets were named after the mineral, not the other way around; the Greeks noted that lodestones interacted with iron and could be used to propel and attract small bits.  Unfortunately they also sort of confused it with static electricity.  Confusing magnetism with static electricity is an understandable mistake, considering the whole "electromagnetism" thing.  Thales of Miletus, one of the Seven Sages of Greece and first philosophers, wrote about magnets during 600 BC, and and in the same writings noted that when he rubbed fur on amber, he could attract specks of dust and feathers.  Thales sounds like he would either have been very, very interesting, or very, very boring.

The Insane Clown Posse and the Greeks weren't the only civilizations to be enamored with magnets, of course.  The Han dynasty in China (300 - 200 BC) used lodestones for compasses; small pieces of iron laid in water over loadstones would always point toward Earth's magnetic north.  European and Arabic culture caught on about a thousand years later, using compasses to sail their ships.  And magnets weren't just used to entertain bored philosophers or navigate trade routes; the Indian surgeon, Sushruta, (500 BC) used magnets in surgery to remove small bits of metal from his patients.

Even if we humans weren't using magnets to guide our ships, magnetism plays a critical role in our lives.  The Earth is surrounded by a couple of invisible rings called the Van Allen radiation belts.  These belts are filled with charged particles that came from solar winds and cosmic rays, and were caught in our magnetosphere.  By trapping the electrons from solar wind, the Earth's magnetic field deflects those energetic particles and protects the atmosphere from destruction.  Without a magnetic field, charged particles would peel away the ozone layer that protects the Earth from harmful ultraviolet radiation, not unlike a hair band from the eighties spraying aerosols all over the place.  In fact, we think that's exactly what happened to Mars: eighties hair bands.

Moral?  Avoid Radical Styles

No, wait.  It was the solar wind thing.  The dissipation of Mars's magnetic field allowed charged ions from solar wind ripped electrons away from carbon dioxide, causing its atmosphere to rot away to almost nothing.  Mars does not have a global magnetic field anymore, and solar winds interact directly with what's left of its atmosphere.  Scientists think Mars used to have a magnetic field, just like Earth.  But when Mars cooled down and its inner dynamo slowed, that magnetic field disappeared.  (Side note: magnetism is pretty fragile.  You can demagnetize a magnet by heating it up, cooling it down, or hammering it really hard.  However, electromagnetic forces are not the weakest of the fundamental forces.  That dubious honor goes to gravity, which should really scare you, particularly if you live in one of those upside-down countries like Australia.)  

It's not just humans and the Insane Clown Posse who rely on magnets.  Some migratory birds and insects, in particular bees, use the Earth's magnetic field to navigate.  I hope you clicked on that last link because it also talks about how sleep-deprived bees dance "weirder."  Perhaps to Insane Clown Posse.  Who knows?

How do bees and pigeons do it?  Well, using the boldest and most dramatic of the naturally occurring magnets: iron, of course.  Bees have iron granules in their abdomens, and pigeons are thought to have iron granules in their beaks.  Not just any iron, either, but magnetite, that iron oxide mineral that lodestones are made of.  Scientists tested their theory by strapping magnets to pigeons.  Let me tell you, reader, if that were the sort of experiment my lab had been doing, I never would have left science.

Fortunately for you, I still have sufficient scientific curiosity to explain to anyone interested (lookin' at you, Shaggy 2 Dope!) what magnets are.  We now know they are any object with unpaired electrons that generates an electromagnetic field that interact with electrons and other magnetized objects.  It's usually a hunk of iron mineral but it can also be a pigeon's beak or a goddamn star.  (If you, like me, are the kind of person who is scared by black holes, do yourself a favor and don't look up magnetars, which are incredibly dense, terrifying "dead" neutron stars.  Don't let the cutesy Pokémon name fool you.)

Ultimately, the basis for all science is curiosity.  And instead of laughing at people for being curious, we should take pause and ask if we can learn something from innocent questions such as "how do magnets work?" or "what happens when I strap a magnet to my pigeon?"  You could argue that the only difference between the Insane Clown Posse and the amber-and-fur-rubbing philosopher Thales was that they were separated by thousands of years.  Perhaps in a few thousand more years, Violent J will be considered one of our great sages and philosophers of our time for daring to ask questions.

...or perhaps not.

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