On my fourth viewing of this video, I realized I was looking at... a cat-ion.

@Esfandiar99

7 жыл бұрын

This is fantastic I'm so glad you pointed it out

@nuklearboysymbiote

7 жыл бұрын

too bad anions aren't called dogions

@tristanridley1601

7 жыл бұрын

WHY DID HE NOT TELL US HIS GLORIOUS PUN????

@Roonasaur

7 жыл бұрын

Because everyone has already heard it before. Or at least, anyone with a half-way decent high school chemistry teacher . . . .

@RandomNullpointer

7 жыл бұрын

Or because they aren't living in an English-speaking world

"You are looking slim." "Only in your frame of reference." - how is this not a famous quote? XD

@DekuStickGamer

8 жыл бұрын

+Martin Verrisin lol so true

@The_Reductionist

8 жыл бұрын

+Martin Verrisin it is now

@anthonysimpkins4320

8 жыл бұрын

+Martin Verrisin XD XD i think you just made it a quote

@thalesqwerty7375

8 жыл бұрын

xD

@vothaison

7 жыл бұрын

What about when someone tells me "You are looking fat"? What should I say?

Just saw this 7-year-old video. "A magnetic field is just an electric field viewed from another reference frame." Extraordinary!

@jimjames6112

2 жыл бұрын

Agree fully.

@halisarahparsons6746

2 жыл бұрын

This is why magnets blow my emf reader off the charts!!!

@drslump9314

2 жыл бұрын

Unfortunately the video is wrong. As is shown In "Is magnetic field due to an electric current a relativistic effect?" by Oleg D Jefimenko available to download on Internet, if one assumes that the interaction between moving electric charges is entirely due to the magnetic field, then the same relativistic force transformation equations make it imperative that a second f ield-this time the electric field-is also present. Therefore, since it is impossible to interpret both the electric and the magnetic field as relativistic effects, one must conclude that neither field is a relativistic effect. It is a very spread missconception. Several authors have asserted that the magnetic f ield due to an electric current is a relativistic effect. This assertion is based on the fact that if one assumes that the interaction between electric charges is entirely due to the electric field, then the relativistic force transformation equations make it imperative that a second field-the magnetic field-is present when the charges are moving

@MarkOakleyComics

2 жыл бұрын

​@@drslump9314 I just read through that paper. Not being a mathematician, I doubt my ability to explain the concept clearly to anybody. (The acid test for understanding a thing). However.., if pressed.., at 1:30 in the video, the fact that the electrons are moving ought to invoke the same relative principle. But it doesn't. You can't have it both ways. -That is, you can't have a relativistic effect only when the cat is moving, but not when the electrons are moving. Which means the theory doesn't work.

@drslump9314

2 жыл бұрын

@@MarkOakleyComics it is an interesting reading. it shows that what he said in 2:44 is completely wrong. Neither field is a relativistic effect. Some animations are missleseading. I.e. Electrons drift velocity is slower than a tortoise. Some topics are not even mentioned as the role of surface charges

Dude wtf are you serious , I have been asking this question like millions of times too professors and teachers but noone wanted to give me an answer. This channel is sacred for me from now on

@_BerKill_

3 жыл бұрын

someone like me.

@niks660097

3 жыл бұрын

its true though magnetic field is just electric field in a diff. frame of reference, and solves a lot of issues with force fields in general in 19th century, Lorentz found that before Einstein...

@Alkaloid-Odin

2 жыл бұрын

This is a very good educational video, but it is just a special case. For example, a single charge also produces a magnetic field. That can not be explained by applying relativity in this fashion. Advanced maths and Lorentz transformations come in there.

@MJ123and5

2 жыл бұрын

@@_BerKill_ someone like me as well

@ameristanbouli5063

2 жыл бұрын

me too i haven't got any answers until i watched this 😮 8 years wow this is amazing

Wife (While jogging): Honey, am I looking slim? husband: Not even in my frame of reference?

@Nom8d

5 жыл бұрын

So hows your single life going now

@BillAnt

4 жыл бұрын

Trust me, after 20 years in wifey prison, single life feels friggin' awesome! xD

@Nom8d

4 жыл бұрын

@ki kus Is that supposed to be sarcasm or what? What led you to believe i got offended, I implied that his wife got offended and divorced him. Sorry Im confus

@hassanakhtar7874

4 жыл бұрын

@ki kus idiot

@andrjsjan4231

4 жыл бұрын

Destro Metro I didn’t understand your joke can you please explain it again ASAP??

What Schroedinger was trying to say with his cat analogy: Quantum superposition makes no sense. What Derek learned from Shroedinger's analogy: All analogies are better with cats

@homelikebrick42

3 жыл бұрын

It represent cat-ions

@dddd-yo5wh

2 жыл бұрын

Even scientist are obsessed with pussies

@Krackonis

Жыл бұрын

He was making fun of the stupid people who used re-equalization to basically screw up quantum theory, which they did and hence why it makes no sense now.

"A Magnetic field is just an Electric Field viewed from a different frame of reference." Thank you for that mind-blowing definition. I always viewed Electromagnetism from a classical point of view and just started studying Special Relativity, but thanks to this video I see another connection between both theories. Thanks a lot man, you literally made my day!

@drslump9314

2 жыл бұрын

But it is not... "Is magnetic field due to an electric current a relativistic effect?" by Oleg D Jefimenko available to download. It shows it is impossible to interpret both the electric and the magnetic field as relativistic effects.

@Kanzu999

Жыл бұрын

I'll admit I'm also convinced that it's not true. When you do a simple thought experiment of imagining only moving electrons inside the wire (no protons or neutrons) and then an outside electron, one case where the outside electron isn't moving, and then another case where the outside electron is moving in the same direction and speed as the electrons inside the wire. When we do this thought experiment, classic electromagnetism contradicts what you would predict happening when comparing it to the theory where the magnetic force is only a result of the electric force combined with relativity.

@WeirdCreature-su4sp

Жыл бұрын

What happened to electric field and magnetic field are perpendicular to each other and interchange their energy in electromagnetic wave??

@alonsoACR

Жыл бұрын

@@drslump9314 You got wrong what bit though. There is no real world difference between magnetic fields and electric fields, they are one and the same. We use these terms because they make "more sense" in a Newtonian worldview. But the universe is not Newtonian.

@DrDeuteron

Жыл бұрын

@@drslump9314 jefimenkos eq are illuminatin, but a current is just a charge viewed from a moving frame

I’ve been teaching high school physics for 32 years, I and I’m still learning such cool things thanks to amazing videos like this one.

@MohitSharma-ym6kh

3 жыл бұрын

Hey buddy.. I too teach physics in India would love to learn from your experience. If I can get any of ur contact

@_judge_me_not

3 жыл бұрын

Would be very grateful if you teach whatever you learn to your students as well😊 Marks are not everything These amazing concepts will make physics both easy and fascinating for them

@ibonitog

2 жыл бұрын

I know you meant it well, but tbh that's a bit sad (nothing against you!!). How aren't physics teachers required to know this, what kind of joke is uni degree for a highschool (that means right until university right?) teacher to not know this.. So confusing how bad "our" education is before uni and then you go to uni and everything is over 9000 and all profs are angry because you didn't learn it in highschool.. wtf:D

@HR-yd5ib

2 жыл бұрын

@@ibonitog , if understanding relativity were required then there wouldn't be any high school physics teachers!

@ibonitog

2 жыл бұрын

@@HR-yd5ib yeah and that is sad.. in my high school, special relativity e.g. was part of the final year curriculum.

In the case when cat is at rest and it sees electrons moving, the electrons are more densely accumulated and the positive charges are spread out. So according to this logic, even rest charge must interact with magnetic field.

@Alex-gk8ik

4 жыл бұрын

The length contraction happened in 1D but density is 3D. This is a contraction without necessarily density increase. The density should be determined such that the total charge is zero relative to positive particles reference frame, happens to be the same as the observer or anything "at rest".

@nikhilnegi9446

4 жыл бұрын

Alex Yang please explain it more deeply. I didn't get what you said about 1D and 3D density

@dilsara7591

4 жыл бұрын

Emergy Man you are absolutely right. There is a flaw in this videos explanation.

@TheJohnblyth

4 жыл бұрын

Electromagnets might offer a simpler case for illustration. In the loops of wire of an electromagnet, the current is flowing so the electrons in each successive loop are all in the same frame of reference and so are the (to us) stationary nuclei. But to the electrons the nuclei are moving and seem slightly closer together(making the next wire-loop over seem positively charged) and to the nuclei the electrons seem a bit closer together (making the next wire-loop seem negatively charged), so the loops all attract one another, because there is a slight curvature of the spacetime-like manifold that constitutes the force applied by the electric field.

@sharnunirgudi5571

4 жыл бұрын

Ya ur right but only if the wire is thick enough to carry so many free electrons and even if it is thick charge wouldn't interact as due to resistance in wire the current decreases

Our Prof linked this video as part of his lecture. So I have to ask: Is this part of the exam?

@220-tejasagi6

4 жыл бұрын

Ur lucky to have a professor lime him.

@SumNutOnU2b

3 жыл бұрын

According to Schrodinger it will be both on the exam and not on the exam.

@pbj4184

3 жыл бұрын

And the answer is - Doesn't matter!

@manofculture8666

3 жыл бұрын

@@SumNutOnU2b I literally just watched a video on Schrodinger lol.

@mm210tx

3 жыл бұрын

@Max....you saw @Donks comment and watched that video for the sole purpose of leaving that comment. Also does this have anything to do with the confounding fact that some people are rubber and some people are glue?? Unfortunately I’m glue and I’d like to change that if possible.

For those who ask themselves, why the electrons dont come closer together in the lab frame: I think its because only the electrons become contracted not the space in between. Hence, the density of charge doesn't change. When the cat moves, everything it sees is contracted, since everything (also the space between the postitiv charges) moves and the density of positive charges increases. Just my approach though

@m.caeben2578

2 жыл бұрын

This is a very clear view of why the stationary electron stills sees the cable as neutral, while the moving electron does not. Thanks for sharing,

@CyL3Nz

Жыл бұрын

Omg thanks. I thought it was infuriating no one noticed that this was not explained by the video

@KJ4EZJ

Жыл бұрын

This should be the top comment. This was my biggest question coming out of the video.

@oliya7793

Жыл бұрын

i also think the fact that the positive ions are contracted plus the egative ones spread out means that the forces stack up wich is why it's negligable from the lab point of reference

@tenmakouhuk

Жыл бұрын

I have been struggling with this for long and this explanation seems to solve it very clearly. Thanks.

Why the wire has no charge in the rest frame: The electrons do initially experience length contraction as they start moving, but they repel each other and spread out to restore neutral charge. The same can't happen with the protons because they can't move freely in the material. Why a single moving electron produces a magnetic field: The electric field caused by the electron also moves along with the electron, causing it to contract and increase its density.

@HarryBalsark

6 ай бұрын

The contraction is not comparable to compression of air for example

@bibeklakra2587

4 ай бұрын

I agree and I think the wire should have electric field from rest frame like the way you mentioned, which cause the magnetic needle to deflects

@Ivan-vv5lj

2 ай бұрын

Why does the electrons get less dense when the cat moves in frame with them then? Shouldn't their mutual repulsiveness space them out evenly again?

Trying to be flirty with nerds: "You're looking slim" "only in your frame of reference"

@samarthbhat7889

3 жыл бұрын

isnt that like an insult?? that one should move at high speeds to perceive you as slim ,i.e you hella fat XD

I just want to say a BIG THANK YOU for your videos having captions in so many different languages. I started watching your videos and it was a struggle to try to understand English and Physics at the same time. When I saw that you have captions in my language I screamed of happiness! (This sounds weird but I have just realized the eager I have to learn Science) thank you, thank you! It's truly a beautiful thing that your channel is spreading knowledge to so many people all over the world. That's huge.

@jinxy7869

3 жыл бұрын

bonjour

@harshit2345

Жыл бұрын

Which language do you prefer???

@gopalkrishna3803

Жыл бұрын

Which language do you speak?!

@gopalkrishna3803

Жыл бұрын

In India, Juli is a Dog's Name.....😆😂🤣🤧😅

@harshit2345

Жыл бұрын

@@gopalkrishna3803 I think it's a very disrespectful comment. Don't downgrade India's name please

1:20 "so if there were... a positively charged cat nearby," *cat dying sfx*

I was always told electromagnetism is a relativistic correction on a moving electric field but I’ve never actually had that explained. Thanks heaps for that.

@sshreddderr9409

7 ай бұрын

electromagnetism is analogous to you moving a spoon in a cup of coffee. if you move it, fluid from all sides rushes into the lower pressure density area right after the displaced fluid. the whole universe is a fluid, charges are a measurement of fluid (or its pressure) density around matter , which in itself is just stacked fluid waves locked in a standing wave motion by having just the correct wavelengths to perpetually push each other, and whos perpetual movement creates a perpetually lower fluid pressure density around the standing wave, which is called gravity on the subatomic, incoherent scale, and magnetic field when only looking at the stacked force of coherent pull from all the tiny mass units which are aligned to pull together in magnets. there is no need for any kind of relativistic nothing. the amount of charge density might be the same in the entire wire, but the moving charges create an area with lower charge density right behind the displaced charges, which compels the charged behind them and in front of them to move, causing a chain reacting in the wire. the non zero local charge density comes from the transmitted pressure impulse creates by the battery, or more specifically the induced movement. You could use relativistic language to describe this, but it is just semantic confusion for something very simple. you dont stir your coffee with the speed of light, but it still makes the coffee in your cup implode into the center of the lower pressure created by you moving the spoon. you would not use relativistic language in that case, yet the same implosive field is created, just in another medium. the faster you move the more implosive the coffee becomes, and if you were fast enough and pushed only in one direction, a vortex would form that would approach a phi golden vortex spiral more and more with increasing speed. a magnetic field made visible in 3 dimensions looks like a double phi golden ratio vortex, cause it is an implosive field . In text books, the spiral shape is not shown, and the field lines are instead depicted as straight, but thats not true and comes from only doing visual experiments on a 2 dimensional plane, which doesnt show the golden ratio vortices. my point is that its all just changing pressure and fluid dynamics. the entire universe is just a single unified superfluid with its waves forming standing waves, and all fields are just pressure differencials ultimately caused by perpetual standing waves creating perpetual areas of lower pressure, and them stacking on top to appear particle like on a larger scale. in reality, the electrons moving in the wire do not exist as countable units, they are actually an amount of fluid literally flowing through the wire after getting pushed out of their pressure neutralizing areas around the standing waves which form the copper atoms, and that movement creates an implosive force around the wire just like in the cup.

At primary school I never understood why magnets work... Now I see why it never gets explained to kids;)

@pr1m3r

5 жыл бұрын

xD

@-_Nuke_-

5 жыл бұрын

exactly!

@alixsonpl7973

5 жыл бұрын

even adult cant understand

@JanKowalski-wb2fv

4 жыл бұрын

I never understood too... And now I do

@TheFlexXMLG

3 жыл бұрын

@@JanKowalski-wb2fv i still dont haha. here he has a moving charge. but what happens when i put a magnet here? does it have moving charges and thats why its gonna have a “magnetic field”?

A positively charged cat is a cation.

@Dyslexic-Artist-Theory-on-Time

6 жыл бұрын

Love it!!!

@electromorphous9567

6 жыл бұрын

richard meagher oh goood noooo. Why. Why???????

@chasingamurderer

6 жыл бұрын

richard meagher if he wanted you be a idiot, he say, "all know it all's comment Bellow"

@fgvcosmic6752

5 жыл бұрын

Pawsitively charged

@PandemoniumMeltDown

5 жыл бұрын

@@fgvcosmic6752 Oh this went way fur ther than I thought it wood. Joy!

I absolutely love you guys, this is a such a great explanation it literally filled me with joy since I have been trying to understand what magnetism is for months now, but have been unable to find a satisfying answer. The work you guys do is so so so important and I am extremely grateful for this video and all the work you guys do.

I can not thank you enough for this brilliant video! For years now this question has been bugging me but most explanations weren't sticking with me. This was presented so clear that it will finally stick in my head. I always look forward to your videos!

6 years of Electrical Engineering curriculum which included extensive study in EM and I was never taught this...... I'm somewhat disappointed in my university. I actually think I asked this specifically: "I understand all the effects of a magnetic field, but what IS it fundamentally?" and after some discussion of permeability and Maxwell's equations I lamented that no one in that class, professor included, actually knew. We could all describe a magnetic field by its effects and influences and even the qualities and characteristics of materials that can support a magnetic field and the methods of inducing one, but not what it actually is. Thank you so much for this video. I can now (at least more fully) answer that question "What IS a magnetic field".

@dirac17

8 жыл бұрын

+djscurge that's why you should study physics and not just EE

@UteChewb

8 жыл бұрын

+djscurge, I came across this in an intro EM textbook at Uni and it blew me away. It was like a "holy crap, of course" moment. But Maxwell's Eqns were like a beautiful derivation based on laws found from experiment, whereas the Relativity argument was more like a logical derivation from first principles.

@XAVIERLOO1

8 жыл бұрын

+UteChewb Wow. Can I know which EM textbook you is it?

@UteChewb

8 жыл бұрын

loo xavier This was a long time ago but I kept the book because it was so amazing. It is "Electromagnetic Fields and Waves" by Lorrain and Corson. It not only has a solid treatment of EM but it has plenty of examples with detailed explanations. Googling, it appears there is a pdf of the 3rd edition available on the internet. The text gives an in-depth (intermediate level) intro to electrostatics and then before getting into magnetism it covers special relativity. :) I'm sure there are more up to date texts available but I don't know them.

@nunbiz

8 жыл бұрын

+djscurge Don't feel bad about your university curriculum. This is not something that you can teach freshman or even juniors right away. It takes some time to be able to recieve and understand it. This is honestly not something that would be relevant for most EE programs - we teach it to Physics students in their third year.

I got it! I finally got it! I was wondering, from the stationary point of view, why the electrons don't contract and attract the positive cat. It is because from the moving cat's point of view the entire world - the positive nuclei and the wire along with it - is moving. That is why the space between the positive charges contract. Because that space itself (i.e. the wire they're in) is moving in this frame of reference. From the stationary point of view, however, only the electrons themselves are moving. This only means that the electrons are squished down a bit and get flatter, but the space between them (again, the conducting wire) is stationary. Therefore the distance between charges remains the same and there is no change in the charge density. I feel so happy right now. Edit: It turns out this intepretation is not entire correct. In a simplified scenario of two co-accelerating bodies there are basically two possibilities (or more like two ends of a spectrum). If the distance between them stay *constant from the bodies' pov* it will *contract* from an observer's pov. If the distance stays *constant from an observer's pov* it will *expand* from the bodies' pov. It depends on how/when that acceleration is applied to the different bodies. Look up Bell's spaceship paradox for more info. But the electrons in a wire seem more complicated than just some constant acceleration. Not sure how exactly it works... but i guess it does.

@Ropbastos

9 жыл бұрын

If the electrons contract but the space around them doesn't follow-up, what is there between the end of space and the electron? And does it occupy no space to not create distance? wtffffff Ok, it's late here now, am I confusing things?

@richardharvey8529

9 жыл бұрын

Ropbastos I'm researching this right now. If you want to PM me (if that's possible on KZread), I could show you what I've found and we could discuss it.

@jeffwells641

9 жыл бұрын

Ropbastos It's the protons that contract, and it's space itself that is contracting. You've got to remember it's not just the time that is relative, it's space AND time that are relative. That's what the illustration of the squished car was all about. From one relative framework (stationary observer watching moving car), the car is squished. From another framework (moving car watching stationary observer), it isn't. In fact, it's the outside observer who is squished! It's not a perception thing, either. Any means of measurement the stationary observer uses to measure the car comes up with a shorter length than the driver of that car would find if measured from his own frame of reference. The car is literally shorter for the stationary observer. So for the cat and the wire, the protons in the wire really are closer together than the electrons when the cat is moving, causing the positive cat to be repelled by the now slightly positive wire. From a stationary observer's perspective, however, the wire remains neutral.

@Ropbastos

9 жыл бұрын

Jeffery Wells "From the stationary point of view, however, only the electrons themselves are moving. This only means that the electrons are squished down a bit and get flatter, but the space between them (again, the conducting wire) is stationary." I'm referring to this part of the main comment. From "Derek's" pov it would be the electrons contracting, no?

@geekbuddy4

9 жыл бұрын

By the analogy in the video, when the camera is stationary, the car squishes while the space (background) remains unchanged. But when the camera moves, the whole space is moving backward in it's frame, so the whole space (background) squishes, hence making its content (positive ions in case of wire) less dense. I feel so happy right now as well. Thanks for helping, Volbla. :)

Why is the wire neutral when current flows through it? Shouldn’t the electrons experience length-contraction from our point of view? Shouldn’t a stationary cat therefore be attracted to the wire?

@Blegie

3 жыл бұрын

From our point of view there is a magnetic field due to the current which is why the cat is also repelled

@fabianwittmann8121

3 жыл бұрын

@@Blegie he means, when the cat is not moving. In the Video he says, that there is no force on the cat, but the electrons are moving and should be contracted out of both perspectives.

@huonghayley

3 жыл бұрын

i was looking for this comment

@tjeerdprins869

3 жыл бұрын

@Fabian Wittmann yes exactly. And also, he says that the flow of electrons is ever so slightly spread out from the point of view of the moving positively charged cat. Is that right though? There’s no such thing as reversed lenght contraction right?

@javiermontoya3018

3 жыл бұрын

I Completely AGREE. In fact we should start demanding the link to the papers or demonstrations, otherwise these animations are just misleading or incomplete

this is my favorite veritasium video of them all on his channel, i had goosebumps man. you have my respect sir...

"If you can't explain it simply, you don't understand it well enough." - Richard Feynman

@AbhishekYadavInd

4 жыл бұрын

Bro he is not Feynman but einstein

@kalki9924

4 жыл бұрын

Nah it was Feynman.. check it

@Chicken_Little_Syndrome

4 жыл бұрын

"We stumbled on this archival BBC interview with American theoretical physicist Richard Feynman over the weekend, and just couldn't stop watching. Filmed as part of the 1983 TV program Fun to Imagine, the interview takes a rather tense turn when the interviewer poses what I'm sure seemed like a very simple question in his head: If you hold two magnets with the same poles close, you'll feel a force pushing them away, and if they have opposite poles, they will snap together. "What I want to know is, what's going on between these two bits of metal?" he says, as Feynman does little to mask his annoyance. "Why are they doing that, or how are they doing that?" For those who haven't seen this clip before, Feynman's response to what anyone would consider a perfectly reasonable question is somewhat off-putting. To be perfectly honest, Feynman initially comes off as a bit of a jerk whose "delicate genius" has been needlessly disturbed. But through his obstinance, Feynman admits that it's actually an excellent question, but one he simply cannot answer in terms that a layperson can understand. "How does a person answer why something happens?" Feynman responds, before launching into an analogy about "why" Aunt Minny slipped on some ice and ended up in hospital. Just as you can't fully explain that scenario without discussing the fundamentals of fluid dynamics, and why you can't properly answer "Why is the sky blue?" without also explaining the concept of Rayleigh scattering, he says you can't explain why magnets behave the way they do to a layperson without first explaining the concept of electromagnetic forces to them. And who knows if they'll even understand that? Feynman tells his interviewer: "I can't explain that attraction in terms of anything else that's familiar to you. For example, if I said the magnets attract like as if they were connected by rubber bands, I would be cheating you. Because they're not connected by rubber bands ... and if you were curious enough, you'd ask me why rubber bands tend to pull back together again, and I would end up explaining that in terms of electrical forces, which are the very things that I'm trying to use the rubber bands to explain, so I have cheated very badly, you see." www.sciencealert.com/watch-richard-feynman-on-why-he-can-t-tell-you-how-magnets-work

@alonsovm2880

3 жыл бұрын

@@Chicken_Little_Syndrome he couldn't explain it to an average person and washes hands saying that they're so average and uneducated that they have to understand principles behind it that they're also too much for their little mind? He's not wrong, but it's no excuse for someone on the "TOP" of historical scientists and idolatred icon and for anyone "educated".

@saswotlamichhane5862

3 жыл бұрын

It was *Einstein!!*

help I'm stuck in an infinite "click here" loop between Veritasium telling me to go to Minute Physics and Minute Physics telling me to come here :-(

@Dyslexic-Artist-Theory-on-Time

6 жыл бұрын

Break the loop check out Quantum Atom Theory!!!

@williambarnes5023

6 жыл бұрын

> Click here There you go. You're welcome.

@somerandom7672

6 жыл бұрын

Do not worry my suggestion-abiding friend! CTRL+F4 will break the cycle!

@erikhendrych190

6 жыл бұрын

Destroy the power plug and incinerate your computer. Problem solved.

Excellent description of relativity and magnetism.

I watched so many videos to understand this and I eventually got it. It really helped me understand it when you looked at the repulsion of the positively charged cat from the cat's and an observer's frame of reference Some insist that there's no such thing as magnetic force whereas from an observer's frame of reference it makes sense to say the cat is repelled due to the magnetic force. The results are the same and thats the main thing. Thanks 🙏👍🏻

But what if the cat is not moving? Aren't the electrons moving relative to the cat, which means more density of electron and thus pulling the cat?

@AlienRelics

8 жыл бұрын

+Michael Englo It is a mistake in the video. With the cat not moving with respect to the atoms in the wire, the positively charged ions (atoms) appear to the cat at the expected distance, whereas the electrons moving past appear to the cat foreshortened and closer together, and therefore a net negative charge from the cat's point of view. So yes, you are correct, the stationary cat feels attraction to the stationary wire with negative electron current flow.

@yogafireyogaflame23

8 жыл бұрын

+Steve Greenfield Someone else in the comments explained that that's not correct. According to special relativity, the electrons themselves would experience length contraction in the stationary cat's frame, but the space between them would not since it's not the space that's moving relative to the cat. Electrons are essentially point charges, so the length contraction of an electron itself has no effect, and the wire remains neutral in the stationary cat's frame.

@AlienRelics

8 жыл бұрын

The length contraction affects the electrons as a group, because they are moving as a group. The spacing appears the same from the electron's frame of reference, but the group has shrunk in length from the cat's point of view.

@yogafireyogaflame23

8 жыл бұрын

Actually, someone else had a better explanation. In reality, both the nuclei and the electrons are moving. In the stationary cat's frame, the nuclei move back and forth but the electrons move around in a way that almost immediately neutralizes any charge imbalance caused by the movement of nuclei, even when a current is flowing, so that the wire remains electrically neutral. When the cat is moving, however, there is no way for the electrons to neutralize the charge imbalance since the electrons appear less dense than the nuclei.

@AlienRelics

8 жыл бұрын

There is no difference. Imagine this: Reverse charges in the wire, with a stationary cat. Stationary negative charges, positive charges moving to the right, stationary positive cat. From the cat's reference frame, negative charges appear normal. Positive charges appear to be closer together and so the cat is repelled. This is exactly the same as the cat moving to the right with the negative charges moving to the right at the same speed. When speaking of something as stationary, this is misleading. Because you can only speak of motion in relation to some other frame of reference. So a stationary cat is a cat stationary with respect to -you-, but you aren't part of the picture. The cat is either stationary with respect to the wire, or stationary with respect to the electrons. In each case, everything that is moving relative to the cat appears to the cat as subject to Lorentz contraction. That includes the entire universe. www.mtholyoke.edu/courses/tdray/phys310/electromag.pdf

I've returned to this video so many times throughout the years, I love it, and it's something I never hear people talk about. This is brilliant!

that video was great,for first time i have grasped the concept of special relativity,i used to float anyway.thanks veritasium keep your lane

Thank you once again for this video. I have always wondered the effects of magnet and possible relationship with relativity.

When the cat was stationary, negative charge was moving with respect to it, so distance between -ve charge should become less and the wire should attract the positively charged cat when it was stationary. Moreover, if the cat starts to move in the direction opposite to the electrons, it should feel even higher force of attraction.

@Ghostrider-ul7xn

2 жыл бұрын

Because the animation in the video is misleading. In reality, you should visualize the positive charges as holes that move opposite to electrons. So they both have equal and opposite velocities so the net effect will make the wire neutral in charge

@maciejnajlepszy

2 жыл бұрын

You need to go to back to Maxwell and ether and magnetism separated from electricity. Read Robert Sungenis.

@DrDeuteron

Жыл бұрын

The electrons all move on separate trajectories such that their spacing is unchanged . They do not constitute a solid object subject to relativistic stresses

@auseryt

9 ай бұрын

​@@DrDeuteronif that would need true it would be unaffected by the moving cat as out would not change. Motion is relative. From the cat perspective it is never moving. The electrons in the wire only change speed and it direction

So I watched your video. You sent me to MinutePhysics, then they sent me to you, then you sent me to them, then they sent me to you... HOW DO I GET OUT OF THIS CYCLE??? **Old woman's voice** It's been ...... 84 years.......

@ArghyaSen93

8 жыл бұрын

Alan Jay Its called an youtube loop.You are stuck for eternity.

@AJ-Channel

8 жыл бұрын

Arghya Sen Awh Naaaaawwwwwwwwh!!

@georgewang2947

8 жыл бұрын

+Alan Jay LOL omg

@fartzinwind

8 жыл бұрын

+Alan Jay Want to know how to keep an inquisitive KZreadr busy?

@emmanuelezenwere

8 жыл бұрын

+Alan Jay, That's what you get when two great persons collaborate.

I just saw a video talking about this video but I cant really understand it, but with this I can fully grasp whats happening and the formation of magnectic field when current passing through!

Wow! What a neat, simple and to the point explanation! Love it

This is absolutely friekin insane!!! I can’t believe my ears and eyes. Relative magnetism. Phenomenal!

Arghh! You guys are just alternating me between these two channels repeatedly. I'll still do it for the love of science 😊✌🏽

Very beautiful concept and a beautiful video

Wow, mind blown. Never thought of this perspective before. Thanks for the video

Woah! Mind blown... I had no idea! So totally cool, relativity is awesome

You brought the relativity spark back in me. I was losing mine. Thanks for this amazingly simplified video.

Happy to learn this. Thanks

Thanks for crediting the music! Made it easy to find :)

this is imho the best video of veritasium! :o

I have seen comments questioning this explanation by saying that the electrons appear to contract when they start moving, creating a net negative charge and thus acting on the cat even when it is stationary. I also had this thought when I watched the video. However, when the electrons start moving and appear to contract from the wire's and a stationary observer's reference frame, the electrons will repel each other from the perspective of the wire and stationary observer until the density of both types of charge are the same. On the other hand, this spreading cannot happen from the perspective of the moving observer because the positive charges are metal ions that are bonded to each other; these charges cannot spread out without stretching and lengthening the wire. The electrons likely cannot contract and neutralize the wire from a moving reference frame because they are being forcefully pulled forward by the electric field that started the current in the first place.

@mokshkothari2507

4 жыл бұрын

Thanks! I was really confused and the comment sections of those questions were filled with hate comments (unlike most science vidoes)

@deepthoughtswithpaul604

4 жыл бұрын

You're welcome.

@rgudduu

4 жыл бұрын

not convincing. Good for the try though. This question needs addressing

Saw this video now, after 10 years it was uploaded to KZread thanks to one of my dear friends. This is so engrossing 🙏🏼🙏🏼🙏🏼 never in my wildest imagination I would’ve thought in this direction. Truly amazing! Thanks 🙏🏼 😊

From my point of view, cats are only attracted to wires that have christmas lights and are plugged in!

so... If the cat is not moving, it is the negative charges that are contracting. Therefore there is a higher negative charge density, and the cat is attracted ?

@swng314

9 жыл бұрын

Guillaume Lemaigre No - that confused me too at first. If electrons are moving right, protons are moving left. There's a sea of ions, positiv and negative, and electron drift also results in positive charges drifting in the opposite direction. From a still point of view, both contract in the same magnitude, and so there's no net charge.

@ricomajestic

9 жыл бұрын

Steven Wang No. That's wrong. In the stationary cat's frame of reference the protons are not moving!

@swng314

9 жыл бұрын

ricomajestic Well, not necessarily the protons are moving. But with electrons moving to the right, essentially positive charges are moving left. Take a neutral charge and a positive charge: ± + Suppose the electron jumps to the right: + ± The electron has jumped to the right, but essentially, the positive charge is moving left. So you're right - no, the protons don't move, but yes, the positive charges are moving left as the electrons move right.

@ricomajestic

9 жыл бұрын

Steven, it depends on the frame of reference. From a stationary cat frame of reference (i.e.- a cat that is not moving relative to the wire), the protons are not moving but the electrons are moving to the right. However, from the electron's frame of reference the protons (and cat) are moving to the left.

@guilemaigre14

9 жыл бұрын

Steven Wang Ok that's much more clear. But still... Just explain me why an electromagnet atract then a piece of metal (like iron). Because the iron is not moving but is still attracted... it just feels like it contradict itself somewhere. (i know for sure that magnetism is really well explained by relativity in term of moving electric charges, but on the concept side, it's not clear to me.)

but then in your frame of reference the negative electrons are moving , and are 'slimer' and so they are more dense,so should'nt the cat attract to the wire

@supersonictumbleweed

8 жыл бұрын

it's just that narrator's frame of reference doesn't matter to the cat and the wire.

@robertbielik5256

7 жыл бұрын

Indeed. The explanation is ridiculous.

@stefanoviviani6064

7 жыл бұрын

Thank you so much for the explanation, man!

@Lolwutdesu9000

7 жыл бұрын

Just one problem with that: in a metal, we don't explain conduction using holes. Not that it's relevant to your explanation but it's just an FYI.

@Lolwutdesu9000

7 жыл бұрын

YiFan Tey there are no "holes". The positive charges are the positive ions in the metallic lattice.

Fantastic explanation, thanks!

I really wish Veritasium could explain some of the workings of human body. Your videos,topics and explanations are outstanding and so are the production methods very interesting.

This is so wel explained damn, such a difficult matter explained in a short amount of time.

you sir, just saved me a lot of time understanding my physics class...

Great explanation and discussion. I am pleasantly surprised by the number of people who are animated by such questions. Makes me feel more “normal”.

One question of the college EM course examine was that : calculate the E & M of two parallel moving charges with speed V (relative to the observer) in terms of the frames of the charges and the observer with Lorentz transformations. In the observer frame, there's force inbetween due to the interaction of a magnetic generated by one of the moving charge and the other moving charge; in the charges' frame , it's the static electric repelling(or attraction) force of the two charges.

Remember learning/calculating this in first year uni physics - thought it was so amazing. Still do.

Girlfriend: "I'm pregnant!" Boyfriend: "Not in my frame of reference." 😎🎶YEAAAAAHH🎶 *drives away*

Derek has got much better at explaining stuff since then!

Awesome.🔥😀 Truly blew my mind. I had heard that electric and magnetic forces are same but never had I been able to connect then how. Your video visualised me that. Thank you😀

If the electrons are moving relative to a stationary observer, won't they be contracted, and thus have a higher density of negative ions compared to positive ions, and thus be negatively charged to the observer?

@AbhishekVerma-iz2hl

4 жыл бұрын

I thinks, bcz of drift velocity are very very small w.r.t to normal movement...

@adrianriebelbrummer5792

4 жыл бұрын

This is because the wire tries to remain neutral under a current so the "real" density of electrons has to decrease slightly to keep the zero charge with the moving electrons. The protons are not moving so they determine the new density of electrons, which has to be the correct one to keep the wire neutral. That's the reason that the proton outside the wire sees no charge when it's not moving relative to the protons. (Sorry for my english)

@MikeSmith-vb8ul

4 жыл бұрын

Lot of confusion here stems from a little oversimplification in this video. The positive charges--or rather, the distribution of positive charge--is in reality not actually static but moves in the *opposite* direction as that of the negative charges. Basically, you can loosely think of it as if an electron migrates away from a nucleus in some direction towards some other positive charge then it's former location because more positive, while the latter becomes more neutral. So, you have like a net negative charge movement or stream in one direction, together with a positive-like charge movement or stream in the opposite direction. So, from a rest charge perspective these opposing streams merely cancel one another out and the so-called "current-carrying" wire overall actually appears simply neutral. But, if that external charge happens to *just so ever budge* into the direction of one of these streams, then it will experience that whole associated effect (magnetic repulsion or attraction) due to the length contraction phenomenon presented in this video.

@CyberAnalyzer

4 жыл бұрын

@@MikeSmith-vb8ul Thank you. Your clarification really helped me out.

@1mrbremos

4 жыл бұрын

@@MikeSmith-vb8ul By that logic, if the cat-ion moved in the same direction as the protons, it would "see" the electrons moving in the opposite direction and thus become more densely packed. And so it would be attracted to them... But that's not what actually happens, is it?

5 years later! & This video perfectly brings back a sense of nostalgia...

@robspiess

3 жыл бұрын

Déjà vu

Wow ! That's crazy ! I never thought it could be so, thanks for this video .

What an excellent explanation....

This is the most amazing explanation I've ever seen about eletomagnetism. Great!!!

Day 62 : I'm still going back and forth from Veritasium to Minute Physics.

Thank you, this is really helpful

This so cool and so simple...Thank you!

i think he forgot to mention this When the cat is stationary, in its frame the only things moving are the electrons (and not the space between them). So the electrons get squished but the distance between its centers is the same, and the charge density remains the same. However when the cat is moving everything moves except the electrons, in the cat frame. So the protons and the space between them contracts, effectively changing the charge density and creating an electric force in the cat frame, or a magnetic force in the stationary frame EDIT- this is my own explaination and I came up with it on my own and I was in 9th class when I came up with this answer one year ago now I am in 10th so I have only some knowledge about relativity and there are lot of new things to learn so maybe this explaination is wrong in that case please correct me. And this is my father's account if you are thinking why I look old

@aumpauskar4653

4 жыл бұрын

I think that special relativity is also applicable to the space time fabric as a whole along with subatomic particles like the proton and electrons and also the members of the elementary particles.

@rohith.peddi7

4 жыл бұрын

Thanks very much.. I have been very confused about this from a long time

@shashankknp

4 жыл бұрын

Thanks for the explanation. I immediately looked into the comment section expecting that someone must have addressed this issue.

@yallG

4 жыл бұрын

@@shashankknp smart bro

@nickolsky

4 жыл бұрын

that is, when a rocket flies at a sublight speed, shrinks not the length of the rocket (from nose to tail) visible by us, but the atoms of which it consists?

This was amazing. Took a whole bunch of stuff I thought I knew and showed how it actually worked. Mind = Blown

Greatest colab evr .

@Veritasium In a circuit, superficial charge are necessary. Charge density is very small but they do have to exist. If not how would we explain the existence of an electric field. It was already known by Weber. It has been discussed more recently by H Härtel and Assis.

I feel the more I understand it the more confused I am. So how does the electromagnet attract a not moving metal object then?

@mukherjee.p

4 жыл бұрын

A not moving metal object has metal atoms with electrons circulating around them. This creates a "magnetic field" for every atom (called magnetic moment, not literally) which lines up with other such magnetic fields of other atoms to temporarily create a magnet with two poles (given if the metal shows paramagnetism)

@mukherjee.p

4 жыл бұрын

A circulating electron is like current across a circular loop, so like a ultra small version of a solenoid

@ivarnyman3417

3 жыл бұрын

@@mukherjee.p exactly, magnets. But in the video he presents a charged particle not an magnet.. and isn't this only a phenomena with AC current? I'm also confused

@mukherjee.p

3 жыл бұрын

@@ivarnyman3417 Well Yeah but not only for AC. Any moving charged particle produces a magnetic field (on top of the electric field it already had). You move an electron (somehow) (doesn't even have to be in a circuit or anything. Simply moving it through space) and it'll create a very small magnetic field. That's the theory

@DrDeuteron

3 жыл бұрын

magnetic field lines want to be in the (permeable) metal, it lowers the field energy the closer the metal gets to the magnetic. Energy changing with position is a force.

how come at 1:18 the cat doesn't experience a force when it isn't moving? I thought that because the electrons are drifting by minutely then they are slightly more dense and contracted and stuff per the video, doesn't that mean the wire will have more negative electrons and be attracting the cat? Where have I gone wrong?

I thank you for this work. This helped me a lot

I am not sure if the explanation can be correct. The Lorentz factor at the speed shown at 3:27 is only 1+5*10^(-25), meaning that the relativistic effect is only 5^5*10^(-25) (because at 0 speed the Lorentz factor is exactly 1). Now I assume a copper wire and proceed to making only a rough calculation with orders of magnitude, which will surfice for my purpose. 1 kg of copper has about 10^24 atoms, and each atom has 11 valence electrons (which are the free electrons in a copper wire), so there are about 10^25 free electrons per kg copper. So if the magnetism is caused by special relativity, there would only be about the charge of 1 electron difference per 1 kg of copper wire. The charge of 1 electron is about 10^(-19) coloumbs, which would not be enough to observe the strong forces that you get, if you e.g. use a coil with 1 kg of copper wire. So either the ecplanation is wrong, or the drift velocity mentioned at 3:27 is wrong.

@alanevery215

Ай бұрын

Eczacly!

I remember learning in relativity that magnetic force is just the consequence of special relativity applied to electric force but never conceptually understood how. This video made it super clear. Thanks!

But, from your point of view, the ELECTRONS are moving, so their seperation should be "ever so slightly" contracted, and since the positive charges aren't moving so there should be a higher density of negative charges in the wire from my point of view and the cat should be attracted to the wire

excellent. Finally I understood.thanx

Wow, that's incredible video !

See the is why I love quantum physics and general relativity, its when you understand the physics is when your head starts to spin, not when you don't understand it ;)

"You are looking slim" "Only in your frame of reference" -Albert Einstein

powerful explanation

awesome explanation thanks bro

2:30 How dare you push that cat over. 🤣

I am stuck in a loop between MinutePhysics and Veritasium😶

Wow!!! I have never looked at electromagnetism in that manner. Amazing as always. Going to show my kids. 😁

I just learned more about magnets than I have in a lifetime. Thank you!

mm something doesn't quite make sense though. If the cat isn't moving and the electrons are, then aren't the electrons contracted in the cat's frame of reference? Therefore shouldn't there be high density of electrons, causing the cat to be attracted to the wire?

@sleepingdeadman1

7 жыл бұрын

I'm gonna just copy and paste a response from another person answering virtually the same question. He explained it really nicely. From "Bob Badeer" a couple of months ago: "In Derek's reference frame, yes electrons are moving and the distance between them is effectively 'slimmer' in his reference frame. But consider this, overall the wire is also neutral. It has to be since applying an electrical current doesn't make a conductor ionized (non neutral) overall. So what's going on? Each time an electron moves from atom A to atom B, atom A has lost 1 electron (it is now positively charged) while B has gained one more electron (it is now negatively charged). It's as if atom B gave a positive charge to A instead of A giving an electron to B. That positive charge is an electron hole. Think of it as money. You have a 100$ bill and I have none. I give a -100$ bill to you : it cancels out your 100$ bill making your net worth 0 while I have lost a -100$ making me richer by a 100$ (2 negatives make a positive). Wealth hasn't been created nor destroyed, only transferred. When an electron moves from A to B, an electron hole moves from B to A at the same time. So in Derek's frame, electrons are moving but holes are also moving at the same speed (thus having the same relativistic effects) making it neutral. In the cat's frame, electrons aren't moving anymore but holes are moving in the opposite direction twice as fast making the wire clearly positively charged thanks to relativistic effects. If you reverse the current, you'd reverse the direction in which holes and electrons are moving. In this scenario, electrons are moving in the opposite direction while holes are stationary in the cat's frame. That is why inverting polarity inverts the magnetic field. Now clearly, the absence of an electron isn't a real particle : it's just a region of space with no electron in it. So where does this positive charge-like effect comes from? From the atom's protons. Remember, we are talking about atoms here and atoms are made up of negative charges (electrons) and positive charges (protons). So when an atom has less electrons than protons, it is ionized (cation or positively charged)."

@bengriffin4027

7 жыл бұрын

That explanation 8sn't satisfactory either. If the positive charges come from the protons, then the positive charges are relatively stationary in the wire....thus no relativistic effects for things in the wires inertial frame. The explanation is insufficient to explain any number of real world phenomena: -even without protons, for example electrons shot down an evacuated tube, the magnetic field is created and will alter the path of moving charged particles. -nothing in the original explanation of follow up attempts explains why a charged particle moving directly toward or away from a current carrying conductor experiences a force that turns it away from directly into or away from the wire. If it were correctly modeled by electrostatic attraction/repulsion, the path would not experience this turning.

@mjtsquared

7 жыл бұрын

Ben Griffin I agree, I don't think that happens, because it's like watching a screen, even if you see a jet dash away in a movie, nothing's really moving, the led lights just turn on in sequential order so the positive charges aren't really being length contracted.

@oldi184

6 жыл бұрын

Dont worry. Most stuff makes no sense in Einstein theories. If you start to consider them seriously and not as an abstract you will get to paradoxes, division by zero, infinite densities or zero volume and negative radius etc. No wonder Nobel committee did not gave him Nobel for that.

@PADARM

6 жыл бұрын

oldi184, says the guy who has "100 Reasons Why Evolution is So Stupid" in his playlist.

I've watched 5 videos today on what magnetism is and none of them actually explained what the "field" is made of or how it comes out of the material and back in again

@PlanetBloopy

5 жыл бұрын

This is the fun part. Mathematically, quantum electrodynamics is by far the best model we've got, but it's cutting edge. I mean, we know fields occupy space, possess energy and momentum, and interact with each other, but we just don't know yet whether they're made of anything more fundamental than themselves, nor if "field" even gives an ideal picture of what's going on. But assuming it does, a particle is a sustained oscillation propagating through spacetime. Each particular type of particle has a corresponding field. Electrons are oscillations of the electron field, and they continually cause momentary fluctuations/disturbances in the electromagnetic field (the field for photons). These disturbances can't be detected directly as they don't have all the right traits to become particles, so we call them a virtual particle and debate whether or not they exist. One way to imagine it is that all the possible positions in spacetime have a state, and each field is like a huge spreadsheet woven throughout, applying formulas to every position. Due to the uncertainty principle, we can't pinpoint an exact position, there are fluctuations everywhere, and the smaller the region we try to observe, the bigger those fluctuations get. With a normal object, the momentary disturbances aren't aligned in any special way so their effects are cancelled out. However, a magnet's unpaired electrons have been aligned so that they have the same 'spin', the effect being that they disturb the electromagnetic field in a consistent way. Electrons of certain other objects then acquire momentum in a common direction when they absorb the disturbances (which are otherwise reabsorbed by the magnet). The arrowed lines drawn coming out of the material and back in show the direction that the acquired momentum goes. But the disturbances themselves reach outwards in straight lines from the magnet in all directions.

@jakejakeboom

5 жыл бұрын

Classical electromagnetism doesn't reflect physical reality, it's just a (really good) mathematical model. Even quantum field theory seems to fall apart in certain circumstances, so we don't have an absolute picture of reality. This is frustrating, but I think being able to visualize electromagnetic waves and fields is still really useful.

@uberXserial

5 жыл бұрын

I like the Thunderbolts project. They have hundreds of videos trying to illustrate what electricity and magnetism could be. The best I've heard is that magnetism is an effect of ions interacting linearly, instead of in a waveform, with the "ether" (space-time.) People don't like that word because it's archaic. But, I understand that a fundamental geometry of reality has been "found" and that's what I think they mean, even if they don't realize it. Anyways, it's been illustrated that the magnetic force is similar to tugging a rope and feeling the effect, as apposed to whipping the rope and waiting to feel the wave, on the other end. This is why there is an "instantaneous" effect when compared to something with a "limited" speed such as light.

@kestutisnikolajevas9870

5 жыл бұрын

look up Magnetism - Ken Wheeler: kzread.info/head/PLjz0SgxcrlEbksk1t13CfZt1p6F8wg2ZH

@ElasticReality

5 жыл бұрын

Electricity and magnetism oppositional forces. They are the same differing only by degree and temperature. When what a magnet approaches absolute zero, it's loses electrical potential and becomes heavily magnetized eventually entering a Quantum locking state were you can position the magnet in three dimensional space and it will remain locked in that position like you were holding it with clamps. Inversely the hotter the metal becomes the more charged the electrical potential increases and the less magnetic it becomes until it reaches its Curie temperature at which point loses magnetism. Everything in science can be thought of in this way, everything has a pole and an opposite Force which is exactly the same, but separated by degree. You can think of magnetism/electricity like an ethereal water, it works very similar. Water evaporates off of the surface of the ocean into hot humid air which condenses into water which then falls to Earth where it is absorbed and eventually mkes it was back to the ocean. A magnet exposed to changing or oscillating poles creates a magnetic field which like evaporation fills the air with electrical potential (humid air) which then collects or inducts the electrical out of the air and and eventually returns to ground or earth.

This is brilliant. Never thought of magnetic fields this way!

Finally, I got it. Thankyou all my lovely teachers on KZread! Thanks a lot.

question: from the observer frame of refference does the electrons also contracts? if so then the observer would be able to observe the special relativity effect on the kitty right?

It's pretty amazing that special relativity explains electromagnetism.

I read this in concepts of physics but can not undertand, thank you so much for great explanation . I watch this video twice

Veryyy awesome explanation

when i saw the title of this video, i was like "GOD, YES!" Awesome. First real explanation of (electro)magnetic fields i ever got. Thank you very much, have an awesome life! :)

My brain won’t let me accept this…

@bommanaakash5900

Ай бұрын

He he i got a big brain

Fantastic explanation 👌

Very nice presentation sir