How Earth Creates Its Magnetic Field

[@kayakutah]

"Not to scale". Thanks, I wasn't sure!

[@idontknowok5632]

😐oohhkayy….

[@MiniWireCoD]

Damn, that circle is nicely drawn.

[@Pile_of_carbon]

Ikr! His first circle was _really_ good.

[@NG-VQ37VHR]

I was disappointed by the second one, but I thought first was pretty satisfying.

[@deepdoodle1]

Whaaat?

[@movax20h]

The first one was AWESOME. The other ones were shit.

[@exeerror-om6cq]

Circle drawing goals

[@sygo]

I LOVE the passion of this guy. He really cares about this, and is clearly willing to dumb it down for the purpose of teaching anyone who asks.

[@Stuart.Branson.]

You certainly can't get any dumber

[@goosee7776]

That's Incorrect unfortunately" cat laughing at how many people thought this was true in the comments" ok folks the planets energy field come's from the suns powerful electron dencity and x rays pass into the earth at its poles' and produce fusion in the center. it's a two part reaction this fusion creates an electron loop or electromagnetic field is a modality" via it's circular magnetic physical property's" a iron, nickle shell" exc,,,this also makes it's spin or rotate itself'' one energy flows counter clockwise from the sun" the em field flows out counter clockwise I believe'... its not a ball lava that's impossible we would be melted by the mass of the heat squared mc_2,,, to what a 5 thousand mile across peace of hot cole would do floating around in outer space ummm no" it's empty after 450 miles debts ish" alot of watter some other things' I can't say" olny fusion "a small star" in the center with not alot of gravity probley near it...so there's acculy nothing there a real bright blueish light, but still not vary hot no...but nice try guy'' however liquid mettal can make a magnetic field yes', but no" there's probably none of that down there, you see especially near all magnetic centurfugal divergence" is a zero point" so there's no gravity to hold any rotating element together so such' Instine was still great tho' thank you lady's and gentlemen," a house cat walks off stage...

[@wycliffeo4656]

Lmao

[@doeeyeddevil4896]

😂😂😂😂 riiiiiight

[@johnbhai7147]

1:12 Mars whole planet radius is 3389 km whereas Earth's core only is estimated to be 3485 km. Thanks for the information, that's the first time i've heard.

[@Dillon....]

he literally describes the magnetic field like a sales pitch like he's trying to convince you that this is what's actually happening lol

[@tylerdurden3722]

It's because he's skipping a certain part, to get to this part. This part explains how the earth's magnetic field is amplified to be what it is. The missing part is how the initial magnetic field is generated(like in a generic planet with an normal iron core) Veratasium was able to realize something is missing. BTW, the amplification part only started 600 million years ago. The earth had a weak magnetic field, and it was weakening with time...then this amplification kickstarted for some reason, and life coincidentally exploded into multicellular organisms (for the previous 3.6 billion years, it was just single celled organisms, and the base magnetic field was fading...then the supercharged magnetic field came to the rescue just in time.) Also, more recent research shows that the inner core has two parts, an inner inner core that's in a plastic state. And the outer inner core has a crystal structure that shouldn't be able to form at that pressure and temperature (without an Iron/Nickle seed crystal from which to grow)... which raises some questions (how did our core get a seed crystal injected into it?...and that seed crystal would have to be very large to not melt entirely during it's journey to the center of the earth).

[@NicholsonNeisler-fz3gi]

@@tylerdurden3722came for this comment - can’t find this info anywhere else

[@SlimThrull]

But what DOES give the Earth the initial magnetic field? I get that for illustrative purposes we can simply impose it, but I'd like to know what the actual answer is.

[@FoxEagle993]

The system being discussed evolves across orders of magnitude in scale. If you're interested you may find resources which delve into the specifics 1. The outer core fluid can hold and generate flux through motion; 2. Local differences form larger composites which are sustained by effects of local motion and charge/flux; 3. Nature favours the lowest energy state. The gradual evolution of the massive system trends toward alignment, leading to initial conditions discussed at 6:00 I imagine the torus of magnetism being more a jagged chain of flux in the system than the smooth shape of a doughnut. (P.S. The magnetic poles are not greatly aligned with the rotational poles)

[@derek]

yeah the thing is that there is positive feedback. A small current or magnetic field can generate the other and they can continue to grow and generate each other in the presence of these helical, turbulent convection currents.

[@KeystoneScience]

SlimThrull sadly, the base of your question, the why, is unknown, we learn more and more about the effects, but many ideas for the why accelerated materials are still hypothetical, for instance, something likely related, it is not yet known how charge is built up in clouds for lighting, all we know is there is a high correlation with stronger updrafts equating to more lightning. So, stay curious, and perhaps you could find it :)

[@SlimThrull]

So the motion of the liquid metal is enough to generate some field which in turn is amplified by the convection currents, yes? Okay, that makes sense.

[@robmckennie4203]

@SlimThrull I don't think liquid metal will generate it's own magnetic field that's then amplified, but there are any number of potential sources of a magnetic field that the core can then amplify.

[@gersontheperson1215]

0:15 lets take a moment and appreciate that circle

[@jeestudent6758]

Ok I did. Now what?

[@omsingharjit]

Yup

[@TheModernMartialArtist]

Hokay, so here's de Earth. Dang, that's a pretty sweet magnetic field, you might say...

[@jgrant4201]

Too few people remember this gem :)

[@blackpink1fan479]

This proves that those places on journey to the center of the earth 2008 movie are real unbelievable and they exist

[@michaelpachuilo6219]

Fire ze' Missiles!!!

[@frankdimeglio8216]

@@jgrant4201 Energy has/involves GRAVITY, AND ENERGY has/involves inertia/INERTIAL RESISTANCE. TIME is NECESSARILY possible/potential AND actual IN BALANCE, AS E=MC2 is F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. TIME DILATION ULTIMATELY proves ON BALANCE that ELECTROMAGNETISM/energy is gravity, AS E=MC2 IS F=ma. Gravity IS ELECTROMAGNETISM/energy. ("Mass"/ENERGY IS GRAVITY. ELECTROMAGNETISM/ENERGY IS GRAVITY.) GRAVITATIONAL force/ENERGY IS proportional to (or BALANCED with/as) inertia/INERTIAL RESISTANCE, AS ELECTROMAGNETISM/energy is gravity; AS E=MC2 IS F=ma. Gravity/acceleration involves BALANCED inertia/INERTIAL RESISTANCE, AS E=MC2 IS F=ma; AS ELECTROMAGNETISM/energy is gravity. (Gravity IS ELECTROMAGNETISM/energy. E=MC2 IS F=ma.) "Mass"/ENERGY involves BALANCED inertia/INERTIAL RESISTANCE consistent with/AS what is BALANCED electromagnetic/gravitational force/ENERGY, AS E=MC2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. Gravity IS ELECTROMAGNETISM/energy. It ALL CLEARLY makes perfect sense, AS BALANCE AND completeness go hand in hand !!! (Very importantly, outer "space" involves full inertia; AND it is fully invisible AND black.) E=MC2 is CLEARLY F=ma. The stars AND PLANETS are POINTS in the night sky. A PHOTON may be placed at the center of what is THE SUN (as A POINT, of course), AS the reduction of SPACE is offset by (or BALANCED with) the speed of light (c); AS E=MC2 IS F=ma; AS ELECTROMAGNETISM/ENERGY IS GRAVITY. E=MC2 IS F=ma. This NECESSARILY represents, INVOLVES, AND DESCRIBES what is possible/potential AND actual IN BALANCE. Gravity IS ELECTROMAGNETISM/energy. The Earth is ALSO CLEARLY then E=MC2 AS F=ma ON BALANCE !!! GREAT !!! By Frank DiMeglio

[@laurenvillarreal1825]

wow, wish this guy was my professor! I'm studying mechanical engineering and this beautifully ties so many concepts in electronics and heat transfer and fluid mechanics. THANK YOU FOR THE POST.

[@goosee7776]

That's Incorrect unfortunately" cat laughing at how many people thought this was true in the comments" ok folks the planets energy field come's from the suns powerful electron dencity and x rays pass into the earth at its poles' and produce fusion in the center. it's a two part reaction this fusion creates an electron loop or electromagnetic field is a modality" via it's circular magnetic physical property's" a iron, nickle shell" exc,,,this also makes it's spin or rotate itself'' one energy flows counter clockwise from the sun" the em field flows out counter clockwise I believe'... its not a ball lava that's impossible we would be melted by the mass of the heat squared mc_2,,, to what a 5 thousand mile across peace of hot cole would do floating around in outer space ummm no" it's empty after 450 miles debts ish" alot of watter some other things' I can't say" olny fusion "a small star" in the center with not alot of gravity probley near it...so there's acculy nothing there a real bright blueish light, but still not vary hot no...but nice try guy'' however liquid mettal can make a magnetic field yes', but no" there's probably none of that down there, you see especially near all magnetic centurfugal divergence" is a zero point" so there's no gravity to hold any rotating element together so such' Instine was still great tho' thank you lady's and gentlemen," a house cat walks off stage...

[@deanlewis1277]

I've had him as a professor and worked in his lab. He's awesome as both a human being and an instructor.

[@ClevorBelmont]

This man almost free-hand drew a circle. I was already impressed.

[@tristanteller7990]

Then ingeniously normalized himself by doing a hilariously terrible placement of the inner circles. Like the Iron Core, my impressed assessment then cooled somewhat

[@eahere]

"It's messy. You're wrong." That's such an Einstein thing to say lol

[@YawnGod]

It's an obvious statement, but I have never heard it in my life: "This core is about the size of Mars. It's big. It's the size of other planets." Cool.

[@Decrosion]

therealnightwriter ha "hollow" is a bad word to use friend because of the crackpot connotations. It's also just inaccurate i mean its obviously not vacuum because that would contradict everything else we observe in nature.

[@Decrosion]

therealnightwriter the dinosaur Gravity point is pertinent though. This seems to be something most people have never heard but remains completely unanswered by mainstream science.

[@renedekker9806]

@therealnightwriter Lol, good joke. You made a mistake, though. For gravity at the surface to be smaller in the paste, the Earth needs to shrink over time, not grow. Or you need to add mass to its hollow core over time.

[@IAMSTEVIERAYBITCH]

@@renedekker9806 can you show me in life where mass is attracted to another Mass. I'm going to answer this really fast for you..... No! Here's an idea start at the beginning trying not to believe the lies that you've been told use your brain for yourself and you will see.

[@renedekker9806]

@@IAMSTEVIERAYBITCH I am sorry, I don't follow your humor. What is mass attracted to if not other mass?

[@Wulthrin]

"this core is about the size of mars" mind blown

[@brokenwave6125]

Why? Mars is half the diameter of Earth.

[@jbenkidu]

@MomoTheBellyDancer lol wow that's not nice. Don't discourage, stimulate.

[@bibekwagle5751]

MC Güx Deluxe b

[@teebee5323]

@@brokenwave6125 exactly, in fact martian gravity is so comparatively weak, it provides a serious hindrance in colonizing mars.

[@Squirt5]

Justin Clonts To start off with, did you know that teenagers who play video games excel at math while those into social media receive below average scores? You’re probably thinking that’s absurd, however yes, it is possible that playing violent or non-violent video games can impact your child’s brain in a positive way by enhancing their skills for different subjects. For example, action-oriented sequences can enhance motor-skills. According to researchers at New York University in Shanghai, a first-person shooter game has led to speedier reactions during road tests on driving simulation software. After further research, war games enhance social skills. It leads participants to treat each other, whether teammates or opponents with surprisingly high degrees of decency. Also, It may come to a surprise to many that a recent study found that teens who were regular gamers actually have amazing scores/results in math, reading and science on their exams. This study that was published in the International Journal of Communication looked at the test scores of twelve thousand fifteen year olds along with their online activities. The Program of International Student Assessment evaluated these 2012 results. Their test measures the student’s knowledge and application of skills in the three subject areas mentioned, math reading and science. A quote from Alberto Posso, professor at Royal Melbourne Institute of Technology’s School of Economics, Finance and Marketing states: “This may be because many online games require players to solve puzzles that, in turn, require some understanding of the three subjects.” Another thing I’d like to address is why play video gamers are aware of the fact that they are only playing a game and are doing things that are fictional, they are just using it as a way to escape reality and enter their own virtual fantasy. I’ve just stated and established that gamers receive excellent scores for Science, English and Math, so it would make sense that these teenagers would be able to tell the difference between a fictional world and reality. Besides science portrayed in video are highly exaggerated, the Super Mario franchise is a good example of this. Teenagers often use the opportunity to play violent video games as a way to relieve stress or anger. If someone is feeling down or is tackling any sort of negative emotions, a way for them to make themselves feel better is to play violent video games. Another study from 2003, by John Colwell at University of Westminster, found that violent gaming was associated with reduced aggression among Japanese youth. For example, Battlefield 1 can be used to support my evidence with the following quote by Stephanie Lind, Associate Professor, Queen’s University, Ontario: “Battlefield 1 is often called an immersive game by its players, but an understanding of immersion that relies on players believing that the game is reality would imply that players identify as first World War-era soldiers”. The quote explains that players always know what they’re playing. Therefore, they are free to move among the different roles the game provides. Players embrace the flexibility of that feature and come in and out of moments of immersion, breaking the player and character. In other words, the players are completely aware that they’re playing a game and playing within a fictional world. This fiction can provide experiences and viewpoints not possible in real life

[@Marcio100s]

A recent scientific publication on the "Origin of Geomagnetism" shows "A New Hypothesis to Fully Justify the Generation, Maintenance and Behavior of Geomagnetism". Just search.

[@gustavderkits8433]

Notice the word “hope” in the explanation. They can generate a lot of little fields, but cannot say why all the little ones coalesce into a giant dipole. Still messy. Still a lot of work to do.

[@shpadoinkle_wombat]

Great video! I would love part two with the topic of "how we actually know all this things". Like how can we know the chemical composition of the core? What proves this theory besides that it fits the observation of large scale magnetic field? etc.

[@doeeyeddevil4896]

👍🏽👍🏽👍🏽👍🏽 exactly my thoughts!

[@koalasaw]

one way we know the chemical composition of the core is from chondrites that can be dated back to the time of earth's formation. basically meteorites were pieces of earth's core that didn't get trapped when the earth formed.

[@Nhoj31neirbo47]

“He nailed it. It’s just complex.”

[@Decrosion]

LOVE OF PLANTS 🌻 fml

[@glenncanfield6211]

Sounds like a bunch of assuming and should bees I don't know we know nothing.

[@mgtowvalues]

@@glenncanfield6211 You are absolutely correct. There was nothing of modern science in this report.

[@nikiwiki2006]

Mgtow Values Seismology has shown a lot of this information.

[@mgtowvalues]

@@nikiwiki2006 Do not blandly tell me that, please. I did the research on seismology and there is nothing in seismology that explains the cause of earth's magnetic sphere.

[@metou3072]

I can't wait for the day that they can make a model of the earths magnetic field that is made the same exact way that earth makes its magnetic field. But obviously I wont hold my breath

[@letstacoboutit8205]

U ever think u could use magnets for energy?

[@metou3072]

@@letstacoboutit8205 obviously the real way Earth's magnetic field is produced is because the earth and sun are electrically connected through birkland currents that you can see with the naked eye... northern lights, Aurora...it also explains why the earth spins..follows the right hand rule.. claiming that the heat that is in Earth's core comes from gravity is total BS... must be a coincidence that electric currents produce heat as well

[@letstacoboutit8205]

@@metou3072 I mean could we use it in a way of a unlimited source some way to harness the electrical field idk too much up on it u knw just researching

[@metou3072]

@@letstacoboutit8205 no.. magnetism is from protons...and electricity is nothing more than moving magnetism

[@metou3072]

If you are interested in making your own energy usually storing it is the issue because batteries are expensive... capacitors are the future not batteries but in my opinion use electricity generated to lift a weight connected to a generator so when you want to use it release the weight to spin the generator...or if you have the batteries to store energy use your car to charge batteries as your battery in your car is only used for starting the car. You waste a lot of energy driving your car around and not capturing all the energy it can produce...you need to learn about diodes...like solar panels use... electricity behaves exactly like water in a pipe... EXACTLY...so if u can understand that then you should have no problem understanding electricity and ways to generate it...if I was you I would save information that you think that you will need later in life cause the internet will not always be there

[@omsingharjit]

2:23 how can volume increase if temperature goes down ?

[@omsingharjit]

4:42 ???? why and how can Magnetic field can be trap in fluids . Why you choose only sulphur ? Why sulphur movement makes magnetic field is it because of sulphur ion ? How do you know there is sulphur responsible for this ? How can Liquid sodium core Expands when it cool down instead of Vise versa ? How that liquid resist the magnetic field ? If it can pass through as field .!!??

[@TeunZijpGroningen]

Why would the dipole be composed of quadruples? Also, changing magnetic fields generate currents, typically eddy currents, which just heats up the metals. I'm skeptical.

[@bjornmu]

So how *fast* is the material in the liquid outer core actually moving?

[@movax20h]

Similar speed to earth surface rotation. 24h per revolution. The speed at the outer bunduary is thus probably something like 900km/h. The turbulent convection and other random motions in the outer corre add and substract a bit from this figure, but on average it is 900km/h, and local variations are probably extremally small. (I do not have any sources, but my guess it is less than 1km/h). My guess, is that the outer core is actually rotating little bit faster, (but could be also little less, we do not know), and using slightly different axis of rotation, but probably within 5 degree of normal axis of rotation. These differences are becuase the things are fluid, and outer core is actually pretty low viscosity, it takes a lot of time to transfer torque and find balance towards equilibrium. Not only that, the outer core also has a magnetic torque and sheer forces, as well due to angular momentum, a differential rotation. So, it is likely the outer core is rotating slightly faster (less than a degree per day) than mantle and surface of the Earth at the Equator, and slightly slower or similar closer to the poles.

[@movax20h]

Update: Apparently, it is even more complex! www.sciencedaily.com/releases/2013/09/130916162005.htm the inner core rotates faster than mantle and surface, but due to reactive forces, this make outer core to rotate actually SLOWER than mantle, thus from the stationary point on the surface, it appears that the outer core is rotating in oposite direction! Fascinating. In the absolute space (lets say from the moon or sun or distant starts perspective), they rotate at similar speeds tho, close to sideral day, which is just few minutes less than 24h.

[@bjornmu]

I'm not talking about the speed of rotation which is rather uninteresting. I meant the *relative* motion of some parts of the liquid relative to other parts. Like e.g . the "speed" of the Golf Stream is measured relative to the surface, not relative to the universe, the latter being quite a meaningless number.

[@movax20h]

There are features in the outer core (liquid part), that do reasamble gold stream, and do form jets, but the relative speeds to the mantle and crust are very small. From my quick calculations it is about 1 meter per hour. Slow.

[@nikiwiki2006]

Wei Zhao Triggered much. Someone stoled your puppy. Your haircut is shit. Oh, by the way, we are living in the best of times in human history.

[@crobbie86]

"Where is it coming from?" Is the most important question.

[@senantiasa]

"and who put it there?" as phoebe said...

[@Shadow-uw3ld]

Mantal part

[@falcodarkzz]

Yeah he doesn’t make that clear. Naturally in the earth’s core there are charges/ions, I guess in a much higher quantity than in normal matter. The motion of these charges is what generates the field. Scientists think this motion is greatest at the boundary between the solid and liquid cores

[@surendrakverma555]

Motion of ions

[@Sam-bc9ll]

Zeb Oh!! Thanks fam, that helps me understand a bit better. So is it like the concept of the “sea of electrons” in metallic bonding?

[@johnstown2451]

6:20 is this like an inverse right hand rule, but the force is causing the field?

[@adityavikram6077]

Where can i find more videos explained by this professor

[@whatthefunction9140]

how quickly is the core freezing?

[@karanbirsingh7884]

It'll freeze over in about 91 billion years last I read.

[@IIGrayfoxII]

in 5,000,000,000 years all life on this planet will be dead. in 7,000,000,000 the sun will become a white dwarf.

[@JimGiant]

1/2 Earth radius - 1/3 Earth radius = 1062km Assuming +Karanbir Singh is correct It will average 1062km per 91 billion years or 1.33 nanometers per hour

[@movax20h]

1mm per year. Seriously.

[@whatthefunction9140]

If I was a giant super god I would dust off the earth. and use that solid crystalline core in some cosmic game of marbles.

[@tezzeret2000]

How exactly does a magnetic field become “trapped” within a fluid? Is it a bunch of iron electrons that are flipping and moving with the iron?

[@tezzeret2000]

If anyone's wondering it's just eddy currents -- sea water is conductive and pulls the magnetic field as well.

[@yashx26]

Miss this channel so much!

[@stephenfulmer1910]

@0:24 holy shit that circle is perfect

[@GillesSaindon]

Does that mean we could maybe measure the electro magnetic activity to determine other planets' activity, age, core make-up?

[@bubblegum-iz8zu]

Let me know if you find the answer

[@Eragon954]

0:14 Casually hand draws a perfect circle, no big deal.

[@Astraeus..]

As Neo said to the Architect, "You haven't answered my question!". You've explained only how the Earth maintains it's magnetic field, not how it was created in the first place, which not only makes the title of your video false but it's also ignoring the most important part of the question in the first place.

[@waiqiao6875]

No, he’s explaining how it’s created. Try watching again or proceed on to other electrodynamics or magnetism courses

[@rameshsabbavarapu3758]

When there is movement of charge it generates field, initial condition was attained by rotation of the earth which forced liquid metal to helical spin.

[@moshcustom]

Interesting, yet I've never seen the heat radiating from the core through the mantle being factored into the calculations regarding global temperatures in the climate models. Also, I didn't catch how a molten iron core can have a solid iron center. But I've often wondered where does the heat at the earth's core come from? And since high temperatures actually cause magnets to lose all magnetic properties, how can it be creating the earth's magnetism? Considering the deepest hole ever dug by man goes only as far as 8 miles, how are we able to extrapolate the composition of the core? Wouldn't we see much larger amounts of iron in volcano lava and magma? Not trying to be a smart ass, just curious....

[@goosee7776]

That's Incorrect unfortunately" cat laughing at how many people thought this was true in the comments" ok folks the planets energy field come's from the suns powerful electron dencity and x rays pass into the earth at its poles' and produce fusion in the center. it's a two part reaction this fusion creates an electron loop or electromagnetic field is a modality" via it's circular magnetic physical property's" a iron, nickle shell" exc,,,this also makes it's spin or rotate itself'' one energy flows counter clockwise from the sun" the em field flows out counter clockwise I believe'... its not a ball lava that's impossible we would be melted by the mass of the heat squared mc_2,,, to what a 5 thousand mile across peace of hot cole would do floating around in outer space ummm no" it's empty after 450 miles debts ish" alot of watter some other things' I can't say" olny fusion "a small star" in the center with not alot of gravity probley near it...so there's acculy nothing there a real bright blueish light, but still not vary hot no...but nice try guy'' however liquid mettal can make a magnetic field yes', but no" there's probably none of that down there, you see especially near all magnetic centurfugal divergence" is a zero point" so there's no gravity to hold any rotating element together so such' Instine was still great tho' thank you lady's and gentlemen," a house cat walks off stage...

[@frootube5662]

This guys an awesome teacher the angular momentum analogy with the convection of the fluid was spot on nice work.

[@HighSpeedNoDrag]

I would like to get his take regarding a area that is off the charts regarding a Aeromagnetic Map which indicates a county Major League magnetic presence. Some strange things at night and will leave at that.

[@captainclone1367]

If the core is cooling down, ergo shrinking, how does the core then expand? 3:30 ish.

[@DougieBarclay]

Water expands when it freezes 🫠

[@KeystoneScience]

Oooo time to watch a video at 2 am :D Edit: was actually 1:30 am.

[@derek]

time to launch a video at 12:30am

[@KeystoneScience]

2veritasium oops, yes you are right, it was 1:30 to me, I was too exited to look at the time

[@koosnaamloos4291]

Keystone Science we need a European science youtuber now

[@sick000fight]

Keystone Science get a life

[@jacksharples4128]

Keystone Science I looked at my watch as I read this and it was 1:30am

[@thelastcube.]

2 videos in one day Is it Christmas yet?!

[@medokn99]

but...

[@hollisatlarge]

I highly encourage viewers to look for different explanations.

[@peacelove6817]

I am...trying to explain to a child and this was nonsense

[@ChetanMayur]

@@peacelove6817 😂

[@fazdianafarhanats]

He is talking nonsense. Earth is spinning.. Basically, the outer part of Earth is a solid inner part of it liquid with differentials in density, which causes differentials in turning speed eventually created magnetic field similar to dynamo.

[@footballCartoon91]

What he really means is that .. Magnetic field of the earth Is coming from the magnetic field of a metal element of the periodic table or the interactions of those metallic elements creates the Earth's magnetic field

[@rickevans3959]

@@footballCartoon91 some of his facts work some don't liquidity is probably a big nuclear reactor the earth is one big China syndrome

[@tomburns5231]

Isn't the explanation from 3:35 onwards just a circular argument? i.e. he explains the creation of magnetic fields via the manipulation of larger magnetic fields and planet core liquids which create smaller magnetic fields which in sum create the larger magnetic fields.

[@dylanhenry3310]

Writing a topical paper on Ganymede for my astronomy class and watched this video for some background context. Jon Arnou's name sounded familiar and I check the citations I have and sure enough, he has co-authored the papers I've used that are focused on the geodynamo in Ganymede. What a coincidence! Thank you Derek!!

[@melomania2637]

Explain like im five

[@medokn99]

r/explainlikeimfive

[@UrielSuarezElectro]

They never explain like you're five - more like ten.

[@professoroak3411]

Melomania not flat = magnetic field (Globe Earth) 🌎

[@skillinp1388]

I've seen one or two times that they literally break it down to 5 year old levels

[@mrjbexample]

Tidy your room first and then we can talk

[@mronion597]

The magnetic field cause the fluid to stretch and create the Earths magnetic field. How did the first magnetic field come??

[@moonasha]

wikipedia said nobody really knows but they guess it's the sun's magnetic field; it was way stronger billions of years ago

[@ronyvernet]

One possibility is that the liquid outer core in friction with solid inner core produced electric charges that in movement through the metal induced little initial magnetic fields.

[@josyjoy2836]

God created everything

[@xeno2421]

@@josyjoy2836 if you are so sure about what you think why are you here? Please don't spam the comment section of scientific viedos

[@Guildrum]

However, the thing that occurs to me as someone who does some welding, I know that mild steel will loose magnetic properties at about 1420° F and will not regain them until it cools to about 500° F. Since steel is made from iron, and it's the iron that imparts the magnetic properties to steel, I assume that iron shares this property of losing magnetism at critical temperatures, yet a magnetic field is still generated.

[@dave5194]

Guildrum I've got a hazy idea of how this works but from what I understand the convection currents cause the fields in the mantel to have helical spirals and creates rings of net current which act like the coils of an electromagnet and the turbulent changes to the field also generates induced magnetic fields as the field "resists" changes

[@Guildrum]

Trust me, I realize that there's no way to know exactly what goes on until someone goes there and directly observes it. :) I know magnetism and electricity are closely related, but I also know, also from welding, that heat effects those relations, as does any welder that's arc welded something too hot and got an arc "blow-out" where the electrical arc will actually try to follow a generated magnetic field due to heat, rather than "do like electricity do" and try to take the shortest route to ground. It seems magnetic fields do strange things at high temperatures, as does electricity.

[@dave5194]

Well he mentioned in the video that there is currently flowing through the mantel and I have seen videos of induction heating from an electromagnet which causes the ingot to levitate and also quickly and evenly heat up. Permanent magnets lose magnetism when they heat up because the molecules are able to move around freely and orient in random directions, canceling out the net force. My guess is that because there's a strong field passing through the molten metal, the molecules are still induced to orient in the direction of the net field

[@sidewaysfcs0718]

It has nothing to do with iron's ferromagnetism, this works with any convecting metal.

[@Guildrum]

And NOW I get around to seeing the main video, where they're talking about sodium!

[@kaitzu4560]

This simulation is just too damn complicated. No creater would create a simulation this sophisticated

[@burt591]

5:02 How fast is the liquid metal spinning?

[@ronyvernet]

The liquid core spins little faster than the earth. Supposing the speed of both are almost the same and the radius of core is about 4350 miles then the speed of core is 1138 miles per hour.

[@punyomilo507]

He said "magnetic field " more than I would blink..

[@theword7377]

He re explained everything he was trying to explain but never explained the magnetic field. Makes absolutely know sense

[@ShouldHaveKnownYT]

“Or we would quickly perish” I love this video

[@bobleclair5665]

You mentioned the little inner spin of magnetized liquid metal,, is there a Coriolis effect present and wouldn’t that effect be shown on the deposited lava bed, making it appear that at one time in history, the magnetic poles flipped and could you explain the Milankovitch cycles and it’s wobbling effect on the earths inner liquid metal?

[@fearlessjoebanzai]

I know pretty much nothing about electric and or magnetic fields, so forgive my ignorance if this is a silly question, but are the fields generated due to the friction of the moving liquid metal core? Or by some other proposed means?

[@davescruton2829]

So far he has not mentioned that the transformer relationship with the sun. You can't map it all out without that tidbit. Remember that the more measurements taken, the more the current paradigm is disproven. When you refuse to see the magnetic and electrical effects in space, you can't understand our own planet.

[@Decrosion]

Dave Scruton Yes thank you. Please keep educating! If anyone wants to understand Dave's comment, just watch this (there's plenty more where that came from). kzbin.info/www/bejne/noGxfqKXobmHjKc

[@bara734]

It's a religious cult... if you contest his dog and pony show they put the cross in your face 😂😂😂😂😂😂

[@caroline61804]

Oh. Good idea. There likely is a connection with the sun and a connection of the sun with orion’s belt. Birkland current anyone?

[@Blilar]

Thunderbolts project

[@masumoto007]

I tend to believe the field is caused by that current from the sun. Also tend to think... the relative motion of the sun... and relative speed...I think of static electricity. Motion, electricity, fields.... motion, they are all intertwined.

[@Squirt5]

This guy is a god. Look at the way he drew that circle

[@DA-bm2mj]

I didn't get how he moved from the cooling Earth to the magnetic field at 04:14

[@sobelgar9289]

Don't think he answered the question... He imposed a field to explain how that field got bigger. The question is where did it come from in the first place? Did I miss something? Also, are we certain about the core elements or are these assumptions? How was this proven?

[@nathangrandlund2259]

Could the earth's natural magnetic field be replaced with an artificial magnetic field and if so what are some reasons that some may try it? Is that something that a facility like CERN could accomplish or do you think it would take many small hubs placed throughout the world?

[@pbj4184]

Before, my question was why does the magnetic field change direction Now, my question is why doesn't it change quickly

[@lunamaria1048]

Nobody knows how Earth generates its magnetic field..... Nobody lol

[@mmmk6322]

You're not suggesting the earth is flat...?

[@Dr.FeelsGood]

@@mmmk6322 how did you infer THAT from what he said, rofl. Nobody knows because no one can fucking actually observe what is going on and test it...it's all a theory based on how we most likely think it is generated based on our limited understanding of what is beneath the mantle..

[@twonumber22]

This guy does.

[@lunamaria1048]

@@twonumber22 No he doesn't. We can only theorize.

[@twonumber22]

@@lunamaria1048 lol

[@reven6e531]

mans wears his watch with the face facing inward that's how you know hes on another level

[@ST-dm3gs]

That's usually an offshore marine thing. It's so the watch isn't damaged by metal rails that are everywhere.

[@Bassillixx]

A particle at the centre of the Earth would experience a vector summation of gravitational forces equal to zero. It would be weightless, and NOT under immense pressure.

[@amogussus2399]

Lol being weightless and being under immense pressure are two diff things !

[@williamdegauven6090]

If I were to try to put this in my own words: so it's the Coriolis effect caused by the Earth's rotation acting on the magnetic elements in the earth's core in a very similar way to how it acts on the Earth's atmosphere to cause rotating storms? And from that movement, which should mostly be in the same direction within a hemisphere but opposite between the hemispheres, generates the magnetic field?

[@janhemmer8181]

The iron in the core is not magnetic because of the curie temperature. The theory here is based on its conductive properties. But the simple fact that no experimental setup with all varieties of rotating conductors has been able to create or even enhance a magnetic field, tells me that there is no understanding of planetary magnetic fields. Just admit that for once, please. The same lack of understanding goes for the phenomenon of differential rotation in planetary bodies and stars. Perhaps the two questions are connected?

[@ronyvernet]

We have high temperatures but also high pressures and a huge radial speed. With all this high energy involved many things can occur.

[@hanskrakaur9830]

Amazing the way he did a perfect circle,

[@DemonDragonGD]

Hans Krakaur Power if science

[@levelwithz3779]

More turds dropped in this video than my dog drops in my yard.

[@studytimewitharshadkhan8439]

Sir why cooling from inside when heat is escaping from surface. Cooling must be at outer surface of this core. As the core is large enough and the process is slow possibility of convection can be ruled out. Please tell

[@shaheenalhirmizy9648]

Is there any indication or printed paper about conviction cells of earth mantle in solid state

[@sean3533]

Or.... everything he said could be wrong. Planetary magnetic fields are a huge area that is unresolved.

[@TheLeontheking]

yes, that fact could have been more highlighted.. i think this is one of our greatest weaknesses, that we want the things we learned to be true. Look at the history.. whenever someone proposed a new concept that broke with establsished thinking, it always took a long while till that new concept even was considered to be true.. scientists have more ego than they generally admit, and more ego than is good for their studies.

[@lorenzo20barnes12ahs]

I agree

[@IAMSTEVIERAYBITCH]

Thank you that's the most truth I read on any of these sites so far. The truth is we don't know it's all speculations. It's very clear the scientist have no idea how a magnet really works if they're going to use it as a Cause at Earth's core.

[@MatrixTerraPlana]

Magnetic field is contrary to the rotation of the earth. Pseudoscience is BS

[@thecritterguy]

Everything he stated is supported by evidence. If you got something better Sean......you're more than free to have it examined by the scientific community.

[@jetsshowbruh7617]

Magnets loose their magnetism when heated so we don't know anything really

[@moa3810]

Amen

[@kekersdev]

You are kind of right and kind of wrong. Earth's core is not like ordinary permanent magnet so saying it would loose it's magnetic field is incorrect. Although earth would loose it's magnetic field eventually but because of some another reason

[@jetsshowbruh7617]

@@kekersdev because of what reason?

[@kekersdev]

@@jetsshowbruh7617 We are not 100% sure how exactly magnetic field is generated but it is definitely related to the movement of liquid metal in the core. This movement happens due to convection between hot core and cold planet' surface so the main reason is core cooldown. The core cools - convection slows down - slower movement in core - weaker MF. After a long time (if nothing special happens) core will completely soludify and MF will be completly gone

[@jetsshowbruh7617]

@@kekersdev yeah ok

[@iammattbarker]

But did he answer your question about where the initial field comes from?!

[@calinculianu]

No, he did not. You know why? Because this professor sucks at explaining. He just likes to hear the sound of his own voice and to finish his diatribe undisturbed. He majorly pissed me off when he didn't stop to explain where the initial field comes from. He sucks.

[@movax20h]

Because the question is actually stupid, and explaining it would involve a lot of math and physics that is not related to the topic. Just take a look at defintion of unstable state, or take a look chaos theory, or instability, positive feedback mechanisms, spontanous symetry breaking, initial condition sensitivity, opamps, turbulence, convection, etc. In the esence, the initial field can be arbitrarly small, so small, that it is not possible to make it smaller in practice (space is always filled with some field, fields and matter and current fluctuations). That is enough to provide initial field, and eventually be huge field. From mathematical point of view it is like asking why it is raining today or not.

[@mrjbexample]

The Earth has small variations in current throughout its entire mass. These might come from reactions between elements, friction, or radioactive decay. The tiny currents have their own tiny magnetic fields, which get twisted and shifted by the turbulent flow in the Earth's outer core. Moving a magnetic field creates a current (Faraday's Law), so it becomes a larger current than the initial one, which in turn creates a stronger magnetic field, and so on. Normally there isn't a positive feedback loop, but the natural convection and 'sulfur' plumes are driving the whole process, converting their kinetic energy into magnetic/electric.

[@Markle2k]

+movax20h Also, the answer is in the companion video on the primary channel that was released a day after this one. Derek erred on the side of dramatic suspense.

[@calinculianu]

> movax20h1 day ago (edited) "Because the question is actually stupid, " The question is not stupid. This is a layman science video. STFU and GTFO with your elitist "is stupid" bullshit. There is no such thing as a stupid question. And lots of people were asking themselves that. You're stupid.

[@no_more_free_nicks]

Finally some in depth analysis.

[@stephanvanhoek7529]

Hey! That has got to be why compasses wern't in common use.! That's been bugging me since I found out blacksmiths have always pointed their drench to the north. Or rather WHICHEVER direction the iron fileings pointed. So it begs to question how often does it move around ?

[@mathiasfantoni2458]

7:14 is where he explains the actual origin of the earth’s magnetic field, if anyone should wonder. Fluid leaves the solid core, and because it contracts the way it does when leaving the surface of the solid core, it picks up angular velocity. You now have lines coming out perpendicular to the surface of the core, and these lines are spinning, so generating small field lines. And the entire earth is also completing a rotation once every day, so these field lines are being dragged around the core in helices with the earth’s rotation. The helices experience turbulence, because they’re fluid, breaking up their perfection, inducing small currents that may fortunately happen to line up with each other to form enormous electric loops that, in turn, induce our protective magnetosphere - or more suiting, magneto…doughnut? ;)

[@omri9325]

Dejavu.

[@derek]

but not dejaentendu

[@tjoms182]

I've just been in this place before

[@professoroak3411]

Lordious I'm back

[@maracachucho8701]

Higher on the streets

[@edthoreum7625]

seen the black cat again?

[@dr.davidbannerf.e.s.6217]

There are absolutely no magnetic fields in super hot liquid metal...quite the opposite. These areas of Earth are where the magnetic field of the Earth is DESTROYED. That's why flying over volcanic areas diminishes the effects of your compass, and it might stop working altogether if you ask the pilot to take you in closer. And if you were to fly over a volcano, and drop a 10pound Nimh grade 40 Nib bar magnet into the mouth of the volcano, that bar magnet wouldn't even stick to a refrigerator seconds later...The Heat of the Volcano would destroy that bar magnet's properties in a HEARTBEAT> I guess I need to be teaching at UCLA instead of this clown....Because even I know the basics of magnetism, and I am just an old skool skater. This problem of heat destroying a magnetic field is also more than likely the actual cause of crashes in and around the Bermuda Triangle Area....I believe that whole area is riddled with Volcanoes, and yes your compass would go haywire because those volcanoes destroy magnetic fields, and therefore would make your compass not function properly while flying over those areas. Just sayin. I could also teach everyone how to gain acceleration and torque using solid magnets...and show everyone how to keep them cool so they retain their power during the run cycles. But I guess kids these days would rather hear about Lava flow and crustal friction making a magnet in the oven of the Earth...Wow!

[@pacthegreatest]

i know nothing about magnets but you must be right because the magnetic poles are in the coldest places of the earth. can you explain in a simple way. thank you

[@dr.davidbannerf.e.s.6217]

@@pacthegreatest Ok, there's a couple of ways to look at it....Let's say we apply heat to get grease off of a pan using dishwashing liquid....Bingo we "loosened the bond" the grease had on the pan's surface...whereas cold water didn't loosen it as much. Or....we could look at it from strictly a movement perspective...like in the way that if something is frozen it stays the way it is...with very little movement...versus heating it up, excites it, loosens it, stops it from staying the way it is...it will melt down in fact if we keep going hotter. So this would destroy the magnets ability to keep or maintain itself....Staying the way it is, and not being excited, moving faster, loosening up, and eventually losing all bonds that hold them together until the magnet is melted completely and becomes it's base elements of nickel, iron, and boron. I suppose you could say that heat loosens the bonds these three metals or materials have between each other in set patterns forming the pole of the magnet...whereas even passing heat close to the magnet will dissipate it's field in that area...until the magnet itself heats up, and the bonds which created that shape of field and pattern start to change and that's when it's no longer a magnet. So a better explanation for the situation of the Earth is that magnetic layer deep under the ground is below the lava layer somehow, and those areas where the lava comes to the surface, are areas where we experience the magnetic field of the area below the lava being disrupted. This would explain airplane crashes in the ocean around the ring of fire, or where a lot of volcanoes are located....The lava is destroying the magnetic field coming from below, making the field strength below be weaker in that area for our instruments, and they give false readings and pilots accidentally crash the plane.

[@pacthegreatest]

@@dr.davidbannerf.e.s.6217 thank you for your time. I will read more about it. I will contact you in the near future to discuss this fascinating phenomenon.

[@bubblegum-iz8zu]

I don’t see how the distortion of the plane’s radar can cause it to crash. The altitude of the plane is way above mountains and the radar system isn’t what’s controlling or keeping the motor from running, the radar system is magnetic and for navigating while the motor is mechanic and is irrelevant to the radar system or magnetism.

[@Albylion]

Do magnetic lines of force always form in the same place around a magnet, or are they improvised depending on environmental factors? In other words, will a static magnet of the same strength, oriented in the same way, always have a magnetic line in the same place surrounding it? Or will it move around in "orbit" around the magnet spontaneously?

[@Microbex]

oh man, i have so many questions. Are the occurrence of the trade winds a direct correlation by the rotations of the magnetic fields?

[@ignacevau]

Nope, trade winds are fairly easily explained by coriolis effect

[@donghooncha6399]

Much better

[@derek]

glad we got that worked out! Thanks for your patience

[@donghooncha6399]

When the first video came out, i only had my right earphone plugged i thought it was about master volume lol

[@donghooncha6399]

Thank you for your reply and all of your highly educational videos!

[@mattb4670]

This guy has no earthly idea what causes the earth’s electromagnetic field....either he has been paid to distort or he has himself been completely diluted. This is the most ridiculous explanation I have ever heard.

[@brandunerbarney4035]

Rectum almost killed um

[@TERRY72763]

This guy Says "The Innermost Third has actually solidified" Like He Knows It, *HE DON;T!* The Deepest MAN has ever Drilled (KNOWS) is 8 miles, by the Russian [YES! RUSSIANS] The *FACT* they found there is That *WE* Know Nothing of the Inner Earths Conditions . Because where there should be Solid Rock, they found loose sentimental layers. Where There should be NO water they found moving water, and temperatures at these depths were not as expected. The lesson is Your ASSUMPTIONS Predicted by Radar waves, Sonar Waves and other Witchcraft *WAS WRONG* Period!

[@graemedunn5824]

"Sentimental layers"? I think it might be you that is being sentimental. Science is not witchcraft. Ignorant people in the Middle Ages labelled anything they did not understand as witchcraft, and it seems like you are doing the same. If you had a CT scan in a hospital, and it found evidence of a tumour, would you dismiss this as assumptions based on witchcraft? Such evidence is based on the behaviour of waves (x-rays in this case). When you see something with your eyes, this is possible due to the behaviour of light waves. The interior of the Earth can likewise be investigated using seismic waves. The technology is very similar in principle to that used in medical ultrasound imaging. Actual laboratory experiments have confirmed that iron is a solid at the temperatures and pressures calculated to exist as the Earths surface. See: science.sciencemag.org/content/330/6002/359

[@onehitpick9758]

@@graemedunn5824 Except that the depth migration required to accurately fathom the earth is highly more challenging and ambiguous than any human physiological ultrasound. We have made great strides in human ultrasound, but we can easily iterate on what we see with image processing to known truth. This trial/verification mechanism does not exist for the inner earth.

[@graemedunn5824]

@@onehitpick9758 You make a valid point regarding the challenge involved, as collection of data about the Earth's interior is extremely difficult. However, the nature of scientific knowledge is such that we model nature using the best data available, making predictions based on these models, and testing these predictions through experiment and observation. These models are not "assumptions". Any and all scientific "facts" are provisional, and represent the best explanations that exist, supported by more and better evidence than any other models. This does not make them fanciful. It makes them the most accurate and justifiable descriptions of the phenomena in existence. All the evidence and modelling that we have points to the idea that the state of the inner core more closely corresponds with our conventional concept of "solid" than to any other state of matter. Terry's post seems to imply that the only way that we can possibly know anything about the deep interior of the Earth is to tunnel into it. Such an assertion is ridiculous.

[@AjLloyd-uy2tr]

Preach brother... these dumbass science bitches need to learn

[@onehitpick9758]

@@graemedunn5824 We can definitely build up some hypotheses about interfaces and velocities vs. depth. We are having difficulty replicating the extremely high temperatures and pressures predicted in the core, in laboratory environments. There are several attempts (such as diamond anvil, etc...) but they are not conclusive yet. One thing I am interested in is the ionic flow in the earth. We definitely have a pervasive ionic flow and potential disperity in the atmosphere due to the, amazing 100V/m electric field gradient. I am interested in how this translates under the earth.

[@Magnasium038]

After a point, I was struggling to follow. But i understand that it's a complex topic to discuss; so i appreciate the effort

[@TheAtmcfadden]

Isnt the temperature of liquid metal above the Curie point? How can that generate a magnetic field? Point charge is flowing in the liquid metal? That doesn't sound right.

[@DanOC1991]

The argument is circular as it assumes the field it then proves.

[@nikiwiki2006]

Dan Wrong. The field exists. It’s measured constantly.

[@ChanTheMan1996]

@@nikiwiki2006 that's not the argument. Whether it exists is not the debate. How it's created is the debate. And how it's explained is circular reasoning.

[@ALIIMRAN558]

If something can amplify a field, it is the generator of the field itself.. The argument is not circular

[@balisticsquirel]

So the magnetic field creates the magnetic field? Tautology much?

[@MatrixTerraPlana]

And magnetic field is contrary of rotation of the earth. Right hand law.

[@DoelowDaPilotman]

SO PEOPLE ACTUALLY BELIEVE THIS?????? Sounds Like They Are Trying To CREATE A Magnetic Field Instead Of Explaining One SMH #FLIGHTZ

[@anaclaudiacabral101]

What does your person believe in btw?

[@jedour865]

This actually really helped answer my questions, thanks.

[@bkstyles5769]

Hello hi there, could you tell me the difference between the electromagnetic field and earth generated a magnetic field, why they seem different from each other, earth EMF interact with everything on earth but electromagnet just interact with metals, etc. thank you

[@nikiwiki2006]

Here’s something for those people that ask questions about the inner core. It explain how we know the composition etc. en.m.wikipedia.org/wiki/Earth%27s_inner_core

[@jimdean294]

Only question I have is that metal looses its magnetic properties at a relitivley low heat 900 to 1400 deg. The core is supposed to hotter than that. So wouldnt the crust (water being abundant and highly conductive) have more of a part to play in the feild?

[@GrieveCreations]

So does the magnetic field change with the seasons from the tilt change?

[@googolnews2781]

Good question.google it

[@justinereyes7608]

5:56 "Im being really friendly" what does that suppose to mean?

[@xyrenegade]

It means he's trying to explain it in lay man's term. Because in Science answering questions almost always ends up with alot of questions. (And happened exactly what I just said)

[@rosman2635]

Hello could you expand on or confirm the following; 1. Is what you state in this video a hypothesis or do you have direct evidence? Its just that if the theory or hypothesis which is basically a guess does not match the observation it surely should be dismissed. 2.Could you explain why there are local and regional variations of magnetic force 3. Could you explain the diurnal and annual inequalities of terrestrial magnetism 4. Have you researched the effects of lunar and solar magnetic declination 5.Why does the position of the North magnetic pole vary over varying periods, as it moves westward and eastward?

[@purabandmonjulsongson3105]

Sir ur first circle was so perfect Thank you sir It helped me

[@squishy312]

When Iron is hot, it's non-magnetic. Is it other elements creating it? Or is the liquid just distorting the field from the solid core?

[@DeerRider17]

1:50 When you say "Mantle Overturning" does that also include the Crust? If so, every 500 million years there are new continents formed, and what once existed gets swallowed into the earth and reset? Or have I gone nuts?

[@russchadwell]

Does lunar gravitational pull play any role on keeping Earth's core hot and partially fluid?

[@etlam262]

What exactly does "rapidly rotating" mean on this scale?

[@Rudisbashar]

When you cant explain it to a six year old...you dont understand it yourself. Ive got a monster magnet,theres no spinning core sire.

[@archockencanto1645]

Yes, so by that logic, no one understands any part of (university level) engineering or biology in the whole world? Just because someone said something and it's popular, it doesn't have to be a rule of the universe. Stop worshipping Einstein.

[@jorgemarkvincentgabriel9204]

It's so hot today so I was worried, and the sun gets hotter everyday. I was thinking if one day the earth's magnetic field wouldn't be enough to protect us from solar flares, and if we could create artificial magnetic field.

[@abinothayyilsanoj4182]

Before that happens we would either be extinct or gone to another solar system

[@Bakersvill]

Yeah i get it but it doesn't answer the question of were the original source of magnetism is created or did i miss something

[@paulneilson6117]

Did you know that there is a charge on the surface of the earth of 1x10^5 coulombs. That many coulombs rotates once every 24 hours. The value obtained is 10 coulombs per second or 10 Amperes. B=(mu0) ni This generates a field that is on the same magnitude of the earth's field.

[@karhukivi]

The lecturer should have mentioned that this mechanism is a "self-exciting dynamo" of which there are many examples, including most of the electrical generators you need for outdoor work. All that is needed is an electrical conductor to rotate and as it does it generates a tiny current from whatever slight magnetism is present. the current adds to the magnetic field which increases the current and the whole process feeds back into itself until the magnetic permeability of the conductor is saturated.