How Einstein saved magnet theory
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- čas přidán 12. 09. 2023
- Magnetism is one of the most bizarre of known classical physics phenomena, with many counter intuitive effects. Even weirder, when one uses Maxwell’s equations (the laws that describe electromagnetism) and traditional Galilean relativity, you can see that magnetism makes no sense at all. However, when one uses Einstein’s theory of relativity, it all makes perfect sense. In this video, Fermilab’s Dr. Don Lincoln helps sort it all out.
Magnetism for parallel wires:
• Magnetism (10 of 13) M...
Magnetism for parallel wires:
• Magnetic Field of a Wire
Purcell simplified:
physics.weber.edu/schroeder/m...
Purcell E M and Morin D J 2013 Electricity and Magnetism Harvard University Mass. Third edition pp 259-264.
Length contraction video:
• Length contraction: th...
Fermilab physics 101:
www.fnal.gov/pub/science/part...
Fermilab home page:
fnal.gov - Věda a technologie
there once was a fencer named Fisk
whose action was exceedingly brisk
so fast was his action
the Lorentz contraction
reduced his rapier to a disk.
If you pass by the Earth fast enough, then the Earth is flat.
@@romanski5811 nah . . . that only happens if the Earth passes by you.
Both scenarios are same.
This can only be observed by one being perpendicular to the sword.
There once was a man called Don
Who was ever so easy to con
He made a great hash
Of physics' worst trash
And all that he said was wrong.
I heard this in passing about 45 years ago. It stuck with me but I never managed to chase down the details. Thank you.
I did know this.... was taught it 55 years ago and remember the feeling of amazement that relativity at such gentle speeds could so precisely explain electromagnetism. Thanks for bringing it all back.... it will help me fade away with a smile.
That was nuts... I was getting more confused but you set me up perfectly for it to click when you brought in the length contraction animation! I'd love to see a video on how this applies to permanent magnets and maybe even induced temporary magnetism.
This is actually insane. So relativistic effects of magnetism happen at such low speeds too? I should probably read the math behind it but one observer's magnetism is another one's electricity? Truly mind blowing!
Depending on the observer's motion, it could be a sum of both magnetism and the electric force that explains the total force on the charged particle.
This must be where ICP gets their name. :V
It's pretty wild that the generation of magnetic fields by currents is an everyday relativistic phenomena (tiny charge density imbalance), and ferromagnetism is an everyday quantum phenomenon (tiny atomic current loops).
The relativistic effects being so tiny and the strength of electromagnetic effects in lab frame or charged particle frame of reference is simply a testimony to the strength of electromagnetism and the very large number of particles involved in a length of wire. Gravity by contrast is orders of magnitude much weaker.
Electric forces are really strong compared to gravity, so it's not at all surprising that low speeds are already have tremendous effects.
Albert Einstein invented Special Relativity to explain Magnetism in his 1905 paper "On the Electrodynamics of moving bodies", where his starting point was the apparent asymmetry of a moving wire and a stationary magnet vs. a stationary wire and a moving magnet.
And here I was, thinking it was really about trains, because of all the train examples and whatnot...
@@danieloberhofer9035 Die Arbeit heißt im Original "Zur Elektrodynamik bewegter Körper" und erschien in den "Annalen der Physik" 1905. In dieser Arbeit leitet Albert Einstein die Gleichungen der Speziellen Relativitätstheorie her: "Man denke z. B. an die elektrodynamische Wechselwirkung zwischen einem Magneten und einem Leiter. Das beobachtbare Phanomen hängt hier nur ab von der Relativbewegung von Leiter und Magnet, während nach der üblichen Auffassung die beiden Fälle, daß der eine oder der andere dieser Körper der bewegte sei, streng voneinander zu trennen sind." (Womit auch klar ist, wo der Begriff Relativitätstheorie ursprünglich herkommt.)
@@danieloberhofer9035 Actually Einstein didn't invent it, he just used the work of myriads other scientists before him. Which is why none of the special relativity concepts bear his name other than "Einstein's special relativity theory", which is but a summary of everything other scientist already found. His genius was making sense of all the things other geniuses found 💁♂
@@Ebani Lol. The same can be said of every scientists. It isn't for no reason that Newton wrote "If I have seen further it is by standing on the shoulders of Giants". Note that even that metaphor is way older than Newton.
@@estranhokonsta newton said the standing on giants thing in response to someone who was very small, implying he would not contribute at all.
I remember this explanation from school. I suppose given that E and M must function in all reference frames you could derive special (probably also general) relativity from the known results. The fact the E is M and M is E through relativistic transformations is so cool. Also it shows just how insanely charge dense normal matter is.
How does all of that work for freely moving charges in a vacuum without the presence of the opposite charge as in the wire?
Remember: It's OK to be a little crazy!
I've heard of this before, but your way of explaining it really clears things up. Now I can say that I know, rather than having heard of this effect. Thanks.
Always a pleasure to learn from these videos. Thank you to everyone involved with these presentations!
if you’re capable of thought, this is a terrible piece.
Thanks for sheding light on (mysterious) magnetism and for providing source with more info. I would absolutely love to see an explanation of why inductors and transformers work the way they do using only this phenomenon!
The concentration of charge due to length contraction causes electrical repulsion thus resulting in what is called the magnetic force. But how does that work for two point charged particles?
This is a good start. I would also note that the Coulomb force is so strong that even a small change in charge density produces a noticeable effect. Also the mass of proton charged nuclei is much greater than electrons and that makes them move slower giving rise to the greater special relativistic contraction of the flow of electrons in the frame of the outside charge observer. It would be fun to look at the difference between AC and DC currents.
what about the random root square speed? and also how about the fact that electrons are Bloch waves inside?
@@mrtienphysics666 It does get fun really quickly!
Well, let's modulate those with laser and we'll obtain some FOCK photon states
I wish he would quantify the cause and the effect, wish he'd show the math
I'm sure it's not too hard.
Phenomenally clear explanation. Congratulations
Please make a follow-up for permanent magnets
Regarding the note about the polarity naming of current flow, I recall an old (older than me) book describing an electrolytic solution. It could and indeed had been used as a rectifier. And because the "material" - positive ions flow was chemically more evident than any flow of the electrons, that became the positive direction. So, the polarity was established by wet chemistry instead of either solid state or gaseous state observations. Such a funny thought!
As always, I truly enjoyed your videos. Thank you, to make the effort to outreach the community.
I had to study the Berkley Physics Course books in the 70´s at the Groningen University so I got familiar then with the idea that magnetism comes from a special relativistic effect. As far as I can remember the explanation was set up differently in the book, but the idea is the same and at the time I was really excited by explanation.
I need to watch this again. Thank you Mr Lincoln.
wow, this is amazing. Relativistic effects at 1mm/s, magnetism explained without those weird right hand rules, exactly what I missed in the high school. May be I would become some magnet engineer if I saw this video at my 16 :)
Hi Dr. Don! Can you do a video on the difference between magnetism and electromagnetism? I'm having trouble understand why like poles on a magnet repel, while like charges on an electromagnet attract.
It's more complicated than the video here, but it's the same thing. For like poles, the electric field is similar to like charges, while for opposite poles, the contraction is more like concentrating opposite charges.
It's >>much
I also would like to see if relativistic effects can explain the permanent magnets. Permanent magnets attract or repel each other without presence of moving charges, right?
@@stefanyankov3801 No. Remember that electrons both move and spin within atoms.
Oh my god I love Sir Don’s
Explanations, he made me love physics
Dr. Don Lincoln with the classic hits, taking us all the way back to 1905, baby! Albert Einstein featuring James... Clerk... Maxwell for this mix, you know it, get your right hand in the air for On the Electrodynamics of Moving Bodies! ⚡
I've done the calculations long time ago, it works great, but if B is entirely a relativistic effect of moving E, how would one describe an EM wave? I've been searching for that, but I cannot find it.
Wouldn't an EM wave be the exact same phenomena just oscillating? Instead of charge moving uniformly in one direction, it changes direction. Acceleration is required to create electromagnetic waves and the change in direction is the acceleration. We describe the oscillation by its relationship to time as frequency and its relationship to the speed of light by wavelength.
You have to derive a 4-vector field. In that case, relativistic effects looks like a 4-rotation of the vectors.
Hi Don, I imagine these very tiny relativistic effects on the moving electrons do matter in the macroscopic world because there are trillions and trillions of them and they add up to a macroscopically measurable force. But what happens if only two of them pass each other along their way? They interact by exchanging a virtual photon, so how does quantum mechanics fit into this picture? Do those exchanged virtual photons between the wires also add up to make that electric force? Should be, but for me that makes it even wilder to imagine... thanks for your amazing video!
And: if you look at many comments below it's amazing how easy it is to get dozens of nobel prize winners to pop up by just mentioning SRT. THAT is Einsteins most magical force it seems.
Hey what about stationary permanent magnets, how can they be explained with the wire theory?
I absolutely love your content!! Keep making it!
I love these videos. Entertaining and informative. I so wish I had these when I was in school.
How does the shortening of the charges themselves equate to a shortening of the spaces between them? The space between them isn't moving and wouldn't contract, I'd think. Why doesn't the external charge just see bigger-than-normal gaps between smaller-than-normal charges?
My question as well.
Quick hopefully useful rake: If two charges are moving past you at some speed relative to your rest frame then they are in a different frame - one moving at their speed relative to you. >Everything< in that reference frame looks shortened in that direction to you including the space between the particles. Think of them as ticks on a ruler. The ruler shrinks so the ticks look closer together to you. The fact that there is no material ruler there, doesn't mean there isn't the "frame ruler".
On top of that, the length contraction does not depend on the direction of current flow. The effect should be the same in either direction.
Switching the charges you look at when you "change" current flow direction does not make physical sense.
If Insane Clown Posse don't understand magnets, then I have no chance
That was great. I remember asking the science teacher in high school why the textbook said it the charge moved in a direction that seemed to be completely the opposite of how he had explained that electricity worked. "It just is the way it is" was his response. I knew I was right !
Fermilab videos .... are everything!
Jesse Pinkman saved magnet theory
You seriously rock! Physics is the most noble science there is.
It’s everything!
Yet another magnetic example of Dr. Don's mind blowing video's! 👍👍💥💥
It's pretty wild that the generation of magnetic fields by currents is an everyday relativistic phenomena, and ferromagnetism is an everyday quantum phenomenon.
Light is both
What’s not wild at all is that you put that exact same comment, word for word on more than one video. Doug, it got old before you even did it, time dilation in reverse!
My puny mammal brain can barely handle these ideas. Great video!
Consciousness power three sets all captives free no longer at the mercy of the child mind mammalian Beast mind rule of Self in our world
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Yepper, lost me.
I can usually keep up.
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The Infinite Sum and the Infinite Product inform the Universal ‘Infinite’ Right Triangle possessing a Hypotenuse ((Infinite Sum/2) value of 4.166666 (=1/.24); Height (Infinite Product^1/2) value of 3.85415 (=1/.259); and Base of 1.583233 (1/.631618); Rest Mass Energy is defined by a Right Triangle’s Height, whereas its Total Mass Energy is defined as Rest Mass Energy + Momentum (Kinetic Energy); its Hypotenuse defines the Infinite Sum/2. The modular configuration is due to θ° forming Mod1/.62; The Hypotenuse/Height defines the Logarithmic Base value (1.08 and its powers at each successive interval). The Inverse reciprocal (1/x) equations of the above define the Precessional Period both at Rest Time (1/.259 x 10^5) and at Total Time (1/.24 x 10^5); this differential accounts for additional momentum/velocity that occurs when the Solar System approaches its Binary Partner Star: Sirius A, contracting the time (Mass-Time Dilation) on the short arc of the cycle to only 21,600 years; versus the long end of the cycle being 25,920 years, the mean value being therefore approx 24,000 years-.
These relationships yield a NEW UNIVERSAL EQUATION for 1/TIME (Rest) = ((Infinite Sum/2 - Infinite Product ^1/2)*((Infinite Sum/2) + ((Infinite Sum/2 + Infinite Product)^1/2)…..finding the solution to the Sum-Product as Right Triangles was a serious breakthrough that has now led our Research Team toward entirely new understandings in Physics. Using our recent discovery of Pythagorean Factorization: Factor 1 = 2.583433 (which is also equal to the Square Root of the Gravitational Constant 6.674 x 10^-11 (N*m^2)/kg^2. Interestingly, 258.3433 ≈ e*(360°). The other factor in the equation is 1/(2.4)^2….. and ALL of the above found in a single ‘Infinite’ Right Triangle derived from the ‘Infinite Sum’ and the ‘Infinite Product’ Arithmetic Progression values of Integers……MeTAtron's MAtriX3x3 OM'E...
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Thanks for this solid review of the basics. So the relative motion of the charges contracts them, effectively concentrating their potency. There is fertile soil here.
Wow yes this concept never fully made sense to me until now, well done great explanings!
It might be an odd tangent, but I think people shouldn't have mocked "F###ing Magnets, how do they work?" Precisely because if this. People think they understand middle school level physics, but they don't realize that their understanding of physics is basically 100 years outdated.
???
As a former ICP fan, I had to defend that constantly.
@@mountfairweathersearch for insane clown posse and magnets
Haha, the lyrics had nothing to do with the complexity of the subject and how many people get it wrong. It was about mystifying the topic and science denial. Just read the very next lines of the song.*
They absolutely deserved every bit of the mockery they got.
*Violent J rolled back the 'liars' claim made in those lyrics and said it was more about scientific explanations destroying the wonder of things, which personally I think is also daft and wrong, but then how would he know? Hes never actually listened to any of them...
@@xtieburn I don't claim to have any insight into what these literal clowns were thinking, and I frankly don't care.
What I do know is that the memes overwhelmingly focussed on that one specific part of the lyrics and did not include the lines that followed. I also know that tons of people felt prompted to provide explanations that overwhelmingly did not rise above middle school level physics.
My point is simply that that even among people who have reached what would be considered a respectable level of education, the percentage of people who can properly explain how magnets work is vanishingly small.
To me, the real mystery about magnetism is ferromagnetism, because it seemingly doesn't involve moving charges.
Electron around nucleus is not static.
My take is that the electromagnetic field generates forces on charges that appear as the classical electric (coulomb) or classical magnetic force depending on the frame of reference, and the difference shows when motion of charges exist. The confusion arises when we mix special relativity with the classical concepts.
The confusion doesn't only arise when we mix SR with pre SR electromagnetism. The confusion arises from the lack of reference frame in Maxwell's Equations. The confusion is what _leads_ to Special Relativity.
Read Einstein's original paper "on the electrodynamics of moving bodies". It is not too difficult.
This is the best channel for science.
Wow, the Lorentz contraction of the "moving" opposite electric charge is a super weird way to get an electric charge effect. It's almost like the opposite of camera perspective distortion, but also not, cause it's about change in position over time, so it's 4D perspective, and cameras produce 2D images...
Others also asked this, but how does this extrapolate (if at all) to how electromagnetic waves work. I know the 2 components are orthogonal, but does relativity explain it too?
Always great content. Thank you.
Well done and clear video on this matter. I learned something new.
If this happens to be a rebuttal of sorts against a snarky and some what rude attack on your channel that just happened to be based on misunderstanding this exact phenomenon, then you sir, are truly a mastor teacher. While it takes alot of smarts to be able to teach this as well as you do it takes profound wisdom to respond like this.
Well, Einstein's original paper on special relativity was called "On the Electrodynamics of Moving Bodies." He starts right away by pointing out the bothersome asymmetry in the usual description of induced emf in a stationary loop with a moving magnet inserted, versus the magnetic force on the charges in a moving loop surrounding a stationary magnet. He then discusses the lack of reference frame inherent in Maxwell's equations, with which Newton's laws don't jibe. The paper is remarkably easy to read for anyone with limited mathematical background. In special relativity, the math is surprisingly simple, although the ideas are not so easy. (This is in contrast to most other topics in physics, like generaly relativity or quantum field theory, where the math is definitely _not_ simple - nor are the ideas.)
A good reason for that is as I have understod it Albert Einstein wasn't all that good at mathematics. He had a very good mind to find new ideas. This is why I can't understand that todays Physicians demand that an idea is calculated through before they even want to consider it.
I am amazed. By the Lorentz contraction equation, the relative lengths would be or the order of 1 part in 1,000,000 or less. It is amazing that such a difference could result in a significant magnetic force between the wires. Amazed.
Great finish! A little confusing to have that teaser in the middle though!
8:56 is the relativistic effect really due to the moving electrons or due to the difference of the electric potential which propagates at nearly c?
Awesome stuff squeezed between nonpareil opening and closing cards!
WOW the world needs more teachers like this
What a fantastic explanation! Thanks
I've heard this explanation before. Thanks for the links to other sources (I haven't checked these out yet) but two significant unanswered questions stick out for me: 1. special relativity has extremely non-linear properties but we learn even in high school physics that magnetic field strength is directly proportional to current; how can a highly non-linear phenomenon give rise to a linear one?. 2. How does this relate to magnetic materials with aligned electron spins?
So cool ! A new video from Don @ Fermilab and "PBS Space Time", on the same day !
I'm TOTALLY blown, never thought a "very simple" concept to a middle schooler actually goes SO deep into the rabbit hole. Thank you, Dr. Lincoln.
I knew this already, but it's always good to see it explained again. It illustrates several important concepts in physics.
First the full meaning of relativity in physical laws - two observers should agree on the general laws, but they may not, indeed often will not agree on the exact explanation for a specific observation, not even on which forces are involved.
Second, it illustrates length contraction as a phenomenon that has observable effects in everyday life!
And third, the electromagnetic force is mindbogglingly strong - even the vanishingly small length contraction of the electron spacings in a wire suffices to generate a charge imbalance large enough to lift objects against the gravitational pull of the Earth.
You forget that according to Einstein there is no gravitadional pull of the earth. It is space time that is bend.
Personally I am yet to be convinced that the Physicians current explanation is correct. In my oppinion it is only one way of looking at it.
When I was I kid I wanted to better understand how the electric guitar worked. That led me to electromagnetism and an interest in physics. Thanks for the video. All this brings us to Jimi Hendrix and then our minds really get blown.
Thanks Don. Mission accomplished 🤯
If the charges are moving faster and contract (become closer together), but the wire they are in is not moving (or at least is not moving differently for the positive and negatives contained within) and thus is not contracted (or at least contracted the same for both pos and neg charges), would that not mean that you need more of one charge or the other in the wire? Where did the extra charge come from?
For current to flow the wire needs to form a loop. On the return leg the spacing of the opposite charge is contracted.
"for magnetism, both charges need to be moving": if you bring in relativity then as soon as one charge is moving there will always be an observer to whom both are moving. how does that add up?
It is my understanding that if you extend the same logic to two differently moving observers, they will not agree on the measurable electric/magnetic ratios of the same objects measured. But they can agree on the same universal outcomes of those differing measurements to a very high degree of accuracy by using Einstein's equations.
I first came across a similiar derivation in "Electromagnetic Fields and Waves" by Paul Lorrain & Dale R. Corson where they do a Lorentz Transformation on Coulomb's Law.
Yeah, well... there are more caveats than that.
For one, E^2-B^2 is a lorentz invariant. This means that a pure magnetic field (like in the case of that generated by the current in the wire) simply CANNOT become a pure electrostatic field (the invariant is negative), no matter what reference frame you swap to. So no, magnetism is not "just" electricity seen from the "wrong" reference frame.
Another caveat is, electrons and protons are NOT billiard balls with charge. They are quantum objects. The wavefunction of electrons in metals (and thus in the wire) is effectively spread over the whole surface. Also it doesn't explain how permanent magnets work, since that involves spin (which is a source of INTRINSIC magnetic moment).
Finally, this explanation makes it sound like magnetism is less fundamental than electricity, while the reality is that they are on equal footing. Two sides of the same coin, the EM field. I feel like these kind of explanations do more harm than good, I'd stick with maxwell.
The explanation doesn't say the magnetic field became an electrostatic field; it says that the magnetic force becomes an electrostatic force. The force is the _gradient_ of the field -- the magnetic field doesn't disappear, only its gradient does.
@@BrooksMoses force is the gradient of potential, not field... Force is directly proportional to field strength...
@@FunkyDexter: Doh! Of course, you're right. I was thinking that the field was the potential field, not the force field.
Wow I guess this also explains why high voltage transmission lines want to snap together if in proximity to one another and so are kept widely separated on towers.
Well, except most of them are alternating current, which raises the complexity by quite a bit.
I think those lines are 3-phase, and I also think they are far apart because they are at huge voltages, not because they want to attract each other.
Veritasium and Minutephysics covered this in a connected pair of vids. Good to find about the Einstein link.
Thank you for this clear and amazing explanation. Electrons themselves are also tiny magnets. Does this mean that the spin of an electron represents actual movement inside of the electron to create this magnetic field?
No it does not represent real motion. But it means you can _think_ about it as if it did, as long as you're careful.
But it does represent real angular momentum. And the magnetic field is related to momentum in space.
Do this mean that there is no detectable difference between a magnetic field and an electric field?
If there were a difference in any way, then you could build a detector to tell you the electric field strength and magnetic field strength at a given point, but that answer would only be valid in the reference frame of the detector.
Great video. A good companion to this is describing gravity in terms of time dilation. I don't remember the exact explanation but The Science Asylum did a great video on it. Something about time running slower on one end of a solid object means it feels a force in that direction, aka gravity.
I watched a S. A. Video where Nick Lucid explained the same as this video, but I think he put a squirrel there to be the observer for the different reference frames you have there.
Thank you, I've been puzzled by this exact thing!
Nice explanation. How we can explain in terms of relativity the magnetic interaction between two single charge with finite velocity?
Nice but false
Exactly. try to lorentz contract a point charge…
Time dilation. When you see two parallel charges move you calculate the force between them with their charges. You observe that they don't accelerate that strongly and call that a opposing magnetic force.
When you consider Relativity you find that the amount by which they accelerate too slowly is exactly the slowing of time you observe due to their motion.
The critical speed where these effects cancel is the speed of light, which they can not reach.
Funny thing is, if you learn geometric algebra, it's just a 4D rotation.
Help. I'm hung up on the relative movement of the + test charge to the + and -- charges in the wire. If the test charge isn't moving relative to the wire in which is flowing a + current it isn't moving only relative to the fixed -- charges of the wire, giving no length contraction. It would see length contraction in the moving + charges in the wire, thus net repulsion? I can only get the test charge (in my head) to feel no attractive/repulsive force if it travels at half the speed of the wire current, where it sees both the stationary -- and current + charges equally length contracted going equally as fast in opposite directions relative to the test charge. What am I not getting straight?
I am pretty sure Purcell was my textbook in my Physics understanding course in 1981! And this was in Brazil!
That is amazing to consider that the super advanced modern concepts of Einstein and Special Relativity can shed light on something we basically cracked a couple hundred years ago in magnets. So fun to see there are constantly new details of the world to probe, even the parts we thought were "finished". The work of science is never done, and as this video shows, is not just a case of "ever more precision" like some detractors say.
Nice!! I used to love the Berkeley series!
The presentation of the material appeared to lack the rigorous mathematical foundation typically expected from your presentations. The explanation was notably reductive, bypassing complexities that merit more comprehensive analysis. I had expected a more substantive education rather than the employment of heuristic/hand-wavy arguments. Accordingly, as @Earwaxfire909 pointed out, "This is a good start."
Fascinating topic, that I am sad I hadn't heard about sooner.
It does bring a question to mind though.
Wouldn't this make the existence of a magnetic monopole even more unlikely?
Also since the magnetism is defined by spatial contraction, what would that mean to magnetism on the scale of a single set of charges, such as a single proton and electron?
Best videos from Dr. Lincoln, period.
But does that effect of length contraction reduce the fundamental charge that each particle carries? Or do the wire "fit more charges" because their length is now shorter?
Classical/Newtonian physics appears to also explain magnetism. It goes like this:
Particles are being bombarded by bosons (or by some other forms of energy) at the same rate from all sides equally. At the same time, they shoot out bosons to all other the place also at some steady rate. Since no other changes, space around is “flat”, I.e. boson pressure if equal in all points of space, thus Newton’s 3rd law “keeps” everything at rest.
Then electricity begin to flow. Electrons start slow march from - to +. Despite the very slow pace, moving electrons generate disturbance in boson field. Sort of like a passing vehicle create air wave. Particles now experience unequal boson pressure (which we call magnetism) that forces stuff to move.
Since particles physically move now, they create even more distortion but grabbing bosons that otherwise would hit other particles, and at the same time bombard others with own bosons at different rate. That new disturbance in turn creates additional difference in electric potentials and thus secondary electric field. And this goes on and on until all particles finally find themselves in a condition of equal forces from all other the place at exactly the same time.
That would also explain electromagnetic wave: like a pendulum, particles try to compensate, overshoot (because bosons have limited speed and arrive with delay), move to opposite direction, start compensating again, overshoot again, and on and on.
Also, would explain why no magnetic monopole was ever found. Or rather every single particle is such a “monopole” and they all equally compensate each other and stay in state of rest until something introduces initial disturbance.
I see Dr. Don; I click!
Yes, I've read and seen vids on this relativistic explanation but they always only explain it using two parallel wires. I don't understand exactly how orbiting electrons in atoms / molecules form a permanent magnetic field. Sure, atomic poles / spin aligns but there appears to be a circulatory force. Permanent magnet materials are work even when not charged is my main concern.
Electrons are a bundle of dynamic charge, so they have a magnetic dipole. This is why they couple into pairs and form covalent bonds. It's almost easier to think of an electron as a magnet, and solididified magnets work because they align unpaired electron dipoles across the entirety of the solid. Electrons are never sitting still, even with no current. What the voltage does is make the electrons jump from atom to atom, which is like perpetually creating a band of unpaired electrons. The current is like a highway of unpaired dipoles, so it mimics the effect of solid magnets with atoms who can support unpaired electrons.
Remember, two electrons can be attracted to form bonds. This is two negative charges overcoming their repulsive forces, and it happens in every atom above Hydrogen and in all covalent bonds. So the real question is, how does the dynamism of electrons lead to their attraction in spite of their like-charge? Or, why does the Pauli Exclusion Principle exist?
@@MichelleHell .. Yes, but a) electrons have a dipole, what is this and where does it come from? Spin... But you are talking about electro-magnets and charge flow. Where is this is in a neutral permanent magnet?
@@PrivateSi Creating one magnet involves using another magnet, forcing the unpaired electrons to spin in the same direction while it's molten, which later solidifies into a uniform arrangement. Quantum field theory might be what you're looking for. Protons can also be aligned with a magnet, so there's basically a lot of spinning charges and they arrange themselves to balance according to their relativistic experience to each other.
@@MichelleHell .. QFT is exactly the kind of fudge I'm sick of. Invent a different particle field for each particle type. It will work in a useful way but it will obscure what's really going on just as much. Yes, magnetic materials align 'spin direction' in a magnetic field, some permanently, some temporarily in the case of ferrous materials. So what is aligned? You've got to explain the left and right hand rules too. What is this EM field and what aligns in a vacuum to form a magnetic circuit? These are ore the questions I'm interested in.
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I prefer to have SOMETHING flowing towards the centre of each particle and all the positrons and electrons that they're composed of (the only proper permanent elementary massive particles that the universe would not waste 1/2 of).. Inflows collide at the centre of each and bounce out at 90' in one plane, spiralling out in another in all directions (spin 0) or with some bias... When charge particles move there's spin bias with spin at 90' to the direction of movement. This spin interacts with magnetic fields in the form of the LH and RH rules.
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These in and out flows also form toroidal loops within loops, squashed into a spherical magnetic dipole. When spins align many of these loops flow to the next spin-aligned particle instead, and as their energy is conserved circuits are amplified outside the object, into the 'vacuum of space' (that's a load of old balls - kick a +ve base quanta ball free with 'Full Escape Energy' and you have a POSITRON, with the excess -ve electro-gas forming an ELECTRON... They are immediately repelled into field warp(ing) balls by the far more balanced, close-packed electro-positronic field around.. These turn into (pulsating, 'spinning') -ve electro-gas pumps as they try to find their balance but never can as the relatively balanced surrounding field will not let them.
I first learnt this theory in Veritasium's channel, feel quite skeptical about it, so I did a rough calculation:
Assuming 1A current flow through φ8mm wire --> electron drift speed ~10^-5m/s order--> Length contraction about 1/10^13 order, for 1m wire moving electrons are packed in (1 - 10^-13)m less
Electron density in conducting metal 10^28/m^3 order --> In φ8mm wire there are 5x10^23 free electrons / m
Which means positive charges in 10^-12m contribute to the "magnetic field"
In 10^-12m distance, positive charge number equal to electron number if there is no current, so there is 5x10^10 difference between positive and negative charges in 1m wire
That's 1.6x10^-19 x 5x10^10 = 9 x 10^-9 C electric field built because of the 1A current flow, if we can really apply specific relativity into this equation
Could someone please try to verify if 9x10^09C electric field does equal to the magnetic field of a φ8mm wire with 1A current?
"Fuckin' magnets, how do they work?"- Albert Einstein
Thanks for explaining that. 🙂
Why do positive/negative charges in the wire move at different speeds when seen from the charge reference frame?
Another remark: it would be more close to reality to talk about electrons moving in the wire and protons standing still, and a lonely electron flying along the wire. That would just flip all signs in the animation, but ofc all the rest would be the same
what about 2 single (point like) charges moving relative each other? Does that create a magnetic field?
Succinct and very informative. Great video.
This is cool, thanks for sharing!
I remember the physics prof going through the argument dispassionately in the lecture while my mind was thoroughly blown. Perhaps he wanted us to forget it so we would be awed by the slow-speed relativistic effect in his field of study (Mössbauer)
Fascinating!
Thanks for the video!
THANK YOU...
PROF. DR. LINCOLN...!!!
Thanks for sharing.
Biggest gigachad of the 20th century, Einstein.
When I first learned about Magnetism and was told it was a related phenomenon to electricity, I concluded that "magnetic forces" were fake forces, and that what we call magnetism must just be a side effect of moving charges, but I never could figure out how it actually worked. I even learned the basics of relativity from other sources, and they didn't specifically mention the connection with electromagnetism, most likely because they focused on measurable length contraction and not the ridiculously tiny amount that's the source of magentism. It wasn't until much, much later, when I was graduated from college and just learning for fun that I came across the connection as this video describe. It still seems mysterious to me, so I try to keep refreshed on how exactly it works.
3:56 The physicist: "Everything I just told you is right"
Me who's not a physicist: "Welp, that's good enough for me"