No, Changing Electric Fields DON'T Cause Magnetic Fields; The Real Origin of Electromagnetic Waves
Vložit
- čas přidán 2. 10. 2018
- For a much more detailed discussion of the origin of electromagnetic waves, see this blog post:
atomsandsporks.com/2018/08/05...
and, in general, be sure to check out the main website:
atomsandsporks.com/
Hello everyone!
It seems like this video has gotten a flood of recent activity, (a bit surprising since it's three years old, but a welcome surprise) and I just wanted to, first, say "hello" to all you new people. Great to see you. And, second, it seems like there's been a sort of new wave of reactions, some negative some positive, to the content of this video so I just wanted to, in a central place, maybe provide some important additional context and discussion. Namely:
1) The human mind thinks in "concepts" but ultimately a physical theory is not a collection of concepts but a collection of math, math that either does or does not match experimental data. And within math it is possible to have so-called DUALISMS. A mathematical dualism is when two sets of equations on the surface look very different, but when you mathematically manipulate them in a certain way you find out that they are actually EXACTLY the same bit of math. Whenever you have such a dualism it is thus the case that ANY and ALL predictions of the one set of equations will be exactly the same in the other, again, because they're secretly the same bit of math, just in a different form.
2) The central set of equations of the classical theory of electromagnetism is often said to be what are called Maxwell's equations. However, these Maxwell's equations have a couple alternative formulations that can be shown to be mathematically DUAL. Thus, any such formulation will exactly make the same predictions and there is no basis for saying one is "correct" and the other is "incorrect" as they are secretly the same thing.
3) One such mathematical dual formulation is what is called a formulation in terms of "retarded potentials" (retarded meaning slowed or time-delayed):
en.wikipedia.org/wiki/Retarded_potential
4) The content of this video is basically just introducing this "retarded potentials" approach to people who may not be familiar with it. This approach should be covered in any good undergraduate textbook on electrodynamics, and is certainly not in any way "my" idea. I am not Lienard, Wiechert or Green, those were the ones who came up with it over a century ago. There also seems to be some notion that this formulation is "fringe". That is definitely not the case, as I said, the content of this video will also be found in any good undergrad textbook, for example, my personal (and I'm sure many others) favorite Introduction to Electrodynamics by Griffiths.
5) When learning a new subject, not everyone "clicks" with the material in the same way and having alternative conceptual and mathematical formulations can be of great benefit to some in learning. If you personally prefer the Maxwell formulation and find it intuitive, then "great!". If you've always found it a bit opaque, well then here's an alternative formulation that, again, is ultimately identical (i.e. mathematically dual) but may "click" a bit better.
6) As many have pointed out, this approach does not carry to a quantum mechanical treatment, but neither does Maxwell's equations and one CAN formulate quantum in a similar way, this is in essence what a so-called Green's functions approach is.
Anyways, hello again to all you new people. Please check out some of the other videos and welcome.
Also, there have been some asking about my qualifications and background. Of course the work should speak for itself but for the curious I have a Ph.D. in Physics (specifically in what is called Condensed Matter Theory, which is basically the field that deals with what happens when you have many quantum objects in something like a solid, or novel solid states like unconventional superconductors or "spin liquids" and such and how they behave) then moved to a more Applied Physics focus when I did a Post Doc for many years (where I worked on everything from new solar cell designs, new approaches to renewable energy and new computer memories to stuff like better ways of formulating electron transport in semiconductor devices in order to better take quantum effects into account). I am now a Senior Staff Physicist at a research-adjacent private company in the field of emerging semiconductor technology.
It's 2021 and I just found it. (; Very well done, thank you!
Why not pin this?
Maxwells equations have been doctored to get rid of magnetic vectors being additive to the electric field.
Steinmetz equations were purposefully sidelined because he states clearly in his electrical oscillations chapter.
that the electrical output can be 200% of the input because of additive magnetic fields.
We have had all the pioneers of electricity together, Tesla , Steinmetz, Elihu Thomson.
And we chose to use maxwells equations???? As the standard?
His equations were purposefully used to completely eradicate the possibly of freeing charges from
Magnetic fields to do physical work.
At only resistive input losses
This will change very soon! With videos like yours and many others theorizing how charged particles attract each other
Thank you for taking the time to make such a concise video and response to it.
I am guessing you are seeing a flood of new activity because of the Veritasium video 'The Big Misconception About Electricity' which went up about a month ago. Its gotten lots of people talking about electricity, electromagnetic fields, etc. The video certainly got me thinking differently about stuff that I've known for years, and my commenting on that video, searching for similar videos, etc. is almost certainly why the CZcams algorithm presented me with your video.
IMHO your comment above about dual formulations of the mathematics is incredibly important. Not only do equivalent but different mathematical presentations trigger different people's intuitions differently, but the different presentations work better or worse in different domains of application.
Thanks for putting this content out there.
-Jon
Agree with @Jonathan Edelson that the Veritasium video is most likely the reason for the influx of activity. His video was very deceptive, creating more misconceptions than he allegedly dispelled with his thought experiment. With everyone thoroughly confused by what he was claiming, there's been a lot of discussion about this topic. It would be nice to see someone of your caliber addressing the issues of that video, more specifically the difference between electrodynamics (e.g. what Maxwell called displacement current) and electrostatics (the direct current).
Brilliant work! Now I need to go pick up and reassemble the pieces of my mind so I can continue down this rabbit hole!
People often confuse map for the territory. It's like when quantum physics was explained in terms of matrices, then same theory was explained equally well with functions (Schrödinger). Then it was shown both approaches are valid and interchangeable. People asked - so is it matrices or functions then? The answer is: "both and neither" - the defining point for quantum physics is actually non-commuting operators (A•B ≠ B•A)- we can construct them with matrices or functions, either will do - because these are just tools to describe the thing.
We often even forget that physical laws are descriptive, not prescriptive. People say "laws that govern the universe" - but it's more like "rules that seem to more or less describe what we observe".
Very true ! I remember my teachers answering my questions with “because those particles must obey the law of …”. And of course, that made me wonder who explained that law to them and if they could be bothered with remembering all of those laws. 😉
@@anonymous.youtuber It's why I love the way ELTE physical chemists do it. Most of my lectures were by done by us proposing some axioms, playing around with constraints and... suddenly, the maths describes an abstract thought experiment that overlaps with a real physical phenomenon.
Experimental-approach to physics is nice. But so is axiomatic, if done right.
But then, I love first principles derivations of difficult concepts.
"We often even forget that physical laws are descriptive, not prescriptive." Wrong. The laws are prescriptive, if they weren't there'd be no reason to describe them mathematically. Ironically, in your comment you are mixing up the "map and the territory" repeatedly. You confuse the "laws that govern the Universe" with mathematical "rules that describe the laws".
@@grixlipanda287 Laws are observations. They don't explain anything. Laws are simply some experimental physicist observing the relationship between two phenomena, and writing a mathematical formula to describe that relationship.
Theories explain why those laws occur using first principles (hopefully).
@@runakovacs4759 The Laws of Nature are things that we can observe, but they are distinct from observations. Mathematical descriptions of laws don't explain anything either, explanations do that. Again, by equating the Law of Physics that we are trying to describe with the mathematical description used to describe it, you are confusing the map with the territory.
I just discovered this channel, and I absolutely love it. SO helpful.
I work in graphics programming, and as a result I both think about light a lot, and have a pretty decent understanding of vector fields and things like that. But I have always been so confused when I tried to actually understand whats *actually* happening with light, and whenever I've tried to look stuff up I always get just countless unending piles of the same old basic explanations.
This is has been extraordinarily helpful. Your channel needs more views.
I'm a laser technician and if you want to have a discussion on light I'll be happy to lead you down the rabbit hole.
Have you ever worked with laser cooling?
Yes, hard to find good explanations from various perspectives.
@@Zenodilodon im in light rabbit hole for last 2-3 days. I still dont have idea how to visualise light. At first I thought it's like an audio wave (longitudal wave). It's nicely seen in shockwave. But I learned today that it's transverse way... But I just cant imagine it especially with the fact it can be polarised and it has 2 compounds perpendicular to each other.. Its so abstract
I'm extremely confused, and Veritasium would argue that means I learned something. Cheers mate excellent discussion!
Thanks!... I think?
That's interesting, and I can see it working in some contexts, but not in most.
If you are teaching a future physicist, you want him to have an understanding of how physics is made. The classical explanation using Maxwell's equations does that quite well. The student sees how physics is produced not by just experimenting and figuring out mathematical functions that describe the results, but also by trying to unify different theories and ending up having made accurate predictions about reality. The story of Maxwell's correction and how that allows the model to support electromagnetic waves, how these waves turned out to have the same speed as light, and how the attempt to salvage this theoretical model lead to Relativity is quite powerful. How would a student get the intuition behind the Liénard-Wiechert potential (or simply the force) if that's what they see when they are first taught the topic.
If you are teaching a future engineer, who mainly wants to know electromagnetism to do calculations, how would an unwieldy formula like that be of more use than Maxwell's equations?
This approach can be useful (in an educational setting) when you want somebody to understand the basic idea behind electromagnetism, without really going far with it and really diving into them math.
It could also be used complementarily to the classical approach, to test the students' understanding by having them figure out why the two ways are equivalent, and how the same phenomena can be described differently.
This is just my opinion anyway. Personally this was a very interesting video to watch!
Well, the way I see it, the Lienerd-Wiechert approach (also called the "retarded potentials" approach, or sometimes the Jefimenko approach) is one-to-one with Maxwell's equations. So in a classical setting neither can be said to be more or less right since they map directly on to each other.
For a new learner, I honestly find the retarded potentials perspective quite intuitive, and Maxwell's equations can be fairly arcane. However if a learner doesn't feel the same then of course they will simply have two options for their "mental picture" if the topic is touched upon.
The retarded potentials approach does fall apart a bit when one moves to quantum physics (though so does Maxwell in its own way) so that is a weakness. But Richard Feynman, for example - one of the big "inventors" of the quantum theory of electromagnetism in the first place - spent a great deal of time and effort trying to cast his quantum electrodynamics theory into a similar picture of retarded potentials. That's how he originally saw the theory. Even if he ultimately was not fully successful clearly he found great intuitive value in the formalism as well.
@@atomsandsporks6760 I didn't know that about Feynman. Thanks, that's quite interesting.
@@aantony2001 No problem! If you're curious to learn more look up the "Feynman-Wheeler absorber theory" which I believe was something of a precursor to the Feynman path integral approach. You can also see his fondness for such an approach by the fair amount of coverage it gets in his Feynman Lectures on Physics (see, for example, II-21)
@@kirkhamandy its the same thing he says here, the change of position and velocity of charges create the B field, charges dont need to move in a particular way as the example in the video, as you see, when they rearch the capacitor what happen? they stop moving! so they are changing their velocity and position!!! thats why there is a change in both fields, this happends until the capacitor fully charges and the charges stop moving in all the circuit.
@@atomsandsporks6760 you mentioned Feynman so i will ask you his famous question "what can you do with it?" see all the concepts you are so condescending toward are in fact tools that we have effectively used in a myriad of ways to understand manipulate and use charge , so here you are with this view point claiming that it is superior so what good is it as a tool? what additional insight does it provide? i mean i get what you are saying don't mistake my question for a misunderstanding of why you are looking at it this way and how it corresponds to the observations BUT i legitimately don't see what the point is , what insight is gained by this view point that is not apparent in the more standard explanations?
This was great and really helped break these misconceptions which I held.
Another misconception break was discovering space time algebra and the idea that the electromagnetic field is a 4-D bivector field, and that itself a derivative of a potential field. I was immediately struck that the B field created by the angle between the electric field and the position vector is a wedge product…? Now how does this relate to how the EM field is perceived based on the motion of the observer?
I wish I understood how to tie space-time algebra, the LW potential, Lorentz force, and relativity all into one coherent concept.
Why is the 'magnetic field vector' perpendicular to both the 'electric field vector' and the 'time-delayed vector', instead of the difference between them?
I think you're going a bit hard on these "misconceptions". After all, that a Magnetic field is caused by a changing electric field is basically a Maxwell equation. Of course your interpretation is not wrong, in your interpretation this just means that they coincide because of the way they are generated instead of being causally related. So basically the interpretation of the Maxwell equation goes from "changing magnetic fields cause an electric field" to "a changing magnetic field is always accompanied by an electric field". The way I see it this is just a shift in perspective and depending on the situation you're trying to understand different perspectives might be more or less useful. If we're talking about light from the sun for example I find it more convenient to think of radiation as its own thing and the details of the charges in the sun would only be distracting. In the end, the math is clear and unambiguous, the way we conceptualize can differ. A good physicist can conceptualize the same phenomenon from several perspectives. Understanding comes from being able to translate between different perspectives.
Indeed. If we merely said that if we observe a changing magnetic field, we can predict something about an accompanying electric field and vice-versa, then I think it removes the OPs objections to these "misconceptions". In fact, Maxwell's equations don't depend on causality to be valid, and we can happily use them in many situations where they provide a convenient means of making quantitative evaluations of some electric or magnetic effect.
@@RexxSchneider And just how do you propose to have a magnetic field without a moving electric field? Hmmmm....
@@glasslinger A steady current flowing through a wire generates a magnetic field around the wire. How do you think electromagnets work? The electric field doesn't move in a DC circuit, it just specifies the rate of change of voltage with distance at a each point.
In a sense the whole Maxwell's theory is a misconception. It's doing great as a mathematical model, but it's far from truth when we are speaking about physics: *the reality*. Though all physics is about creating more and more accurate mathematical models, bat the motivation is (or at least mine is) to understand the reality which is not a model. So our best (current) understanding is that there are "charges" (disturbances in the q-field) and they exchange ... information (?) by virtual (?) photons (disturbances in another, related field?)... the EM field is just an approximation like thermodynamic parameters are approximation of the molecular level...
@@RexxSchneider No. It is MOVING electric fields that generate magnetism! (not changing) The electric charges (fields) of the electrons are MOVING when you apply a current to the wire. You need to consider the problem at the simplest level to get the correct perception.
Awesome video! Thanks for making it. I am reading the blog post now. Can you please make a video explaining WHY the relative motion of a magnet and a conductor induces a current in the conductor?
You either do or do not accept the 4 Maxwell/Heaviside equations are a valid starting point from which to better understand nature .If you do , one equation says that a magnetic field curls about a current or changing electric field , another says an electric field curls about a changing magnetic field .They are coupled ; they co-exist . From these equations one can derive the Wave equation and show that the fields ( electric and magnetic ) are propagating waves that are orthogonal , in phase , and spatially in quadrature , further that they propagate at one speed , c . From this understanding we have been able to build , broadcast radio and TV,sattelite communications , cell phone networks etc . We have also gone on to expand and improve this knowledge bringing it into alignment with relativity . This in turn has enabled us to build the GPS networks and large distance communications. All of this has been rendered possible because our fundamental understanding was correct. Many of the points made in this video are flat out nonsense and if adopted by a viewer , that would be unfortunate .
Hello everyone!
It seems like this video has gotten a flood of recent activity, (a bit surprising since it's three years old, but a welcome surprise) and I just wanted to, first, say "hello" to all you new people. Great to see you. And, second, it seems like there's been a sort of new wave of reactions, some negative some positive, to the content of this video so I just wanted to, in a central place, maybe provide some important additional context and discussion. Namely:
1) The human mind thinks in "concepts" but ultimately a physical theory is not a collection of concepts but a collection of math, math that either does or does not match experimental data. And within math it is possible to have so-called DUALISMS. A mathematical dualism is when two sets of equations on the surface look very different, but when you mathematically manipulate them in a certain way you find out that they are actually EXACTLY the same bit of math. Whenever you have such a dualism it is thus the case that ANY and ALL predictions of the one set of equations will be exactly the same in the other, again, because they're secretly the same bit of math, just in a different form.
2) The central set of equations of the classical theory of electromagnetism is often said to be what are called Maxwell's equations. However, these Maxwell's equations have a couple alternative formulations that can be shown to be mathematically DUAL. Thus, any such formulation will exactly make the same predictions and there is no basis for saying one is "correct" and the other is "incorrect" as they are secretly the same thing.
3) One such mathematical dual formulation is what is called a formulation in terms of "retarded potentials" (retarded meaning slowed or time-delayed):
en.wikipedia.org/wiki/Retarded_potential
4) The content of this video is basically just introducing this "retarded potentials" approach to people who may not be familiar with it. This approach should be covered in any good undergraduate textbook on electrodynamics, and is certainly not in any way "my" idea. I am not Lienard, Wiechert or Green, those were the ones who came up with it over a century ago. There also seems to be some notion that this formulation is "fringe". That is definitely not the case, as I said, the content of this video will also be found in any good undergrad textbook, for example, my personal (and I'm sure many others) favorite Introduction to Electrodynamics by Griffiths.
5) When learning a new subject, not everyone "clicks" with the material in the same way and having alternative conceptual and mathematical formulations can be of great benefit to some in learning. If you personally prefer the Maxwell formulation and find it intuitive, then "great!". If you've always found it a bit opaque, well then here's an alternative formulation that, again, is ultimately identical (i.e. mathematically dual) but may "click" a bit better.
6) As many have pointed out, this approach does not carry to a quantum mechanical treatment, but neither does Maxwell's equations and one CAN formulate quantum in a similar way, this is in essence what a so-called Green's functions approach is.
Anyways, hello again to all you new people. Please check out some of the other videos and welcome.
Maxwells equations have been doctored to get rid of additive electromagnetic fields
@@atomsandsporks6760 Well thanks for the follow up. But what I don't get it why you don't pin down the ten most important topics and keywords and link the wikipedia pages in the description. That would make things a lot easier and accelerate your path for financial support.
Especially since that careful follow up post certainly took more time than searching those few topics
Also how does it explain the far future when the universe has a heat death and nothing is left but photons. There will be no electrons or protons left , where do the photons terminate ?
This video made me try to find my electromagnetics text book from 1975 because I was sure the magnetic field reached a peak when the electric field was zero and rapidly changing and the electric field reached a peak when the magnetic field was passing through zero.
Also the point about two light beams passing through each other would also work perfectly well with Maxwell's equations because all the fields can just add together at the crossing point and then go on their original direction like water waves crossing each other.
The E driving B and vice versa came from maxwells own early analysis before it was fully understood. The fields are certainly correlated and not independent, but that is not the same same as one causing the other.
You really took us behind the curtain. That was excellent and unlike anything else I’ve heard on youtube. I’d really like to see this in more mathematical depth. Can you do a second video where you demonstrate these ideas with some form of Maxwell’s equations (differential forms)? I know you weren’t saying that the distant detector is aware of the current position/velocity/acceleration of the charge (that would mean instantaneous transmission of information), so I believe you are saying the distant detector is comparing it’s last update with it’s current update - it is generating the magnetic field based on the local rate of change of the position-velocity-acceleration of the signal from the distant moving charge. Would a Lorentz transformation be involved here? Could you calculate some examples for us? I took electromagnetic theory some years ago but this explanation was never explicitly taught to me. Thank you. Subscribed!
Before finding this video, I'd spent countless evenings worrying about this same topic, being incredibly discomforted with the mainstream way of illustrating "electro-magnetic waves" and "magnetic" fields.
I initially figured that magnetism and electro-magnetism is actually caused by "time-delayed" feilds and the resultant "kink", and then tried working out the vector mathematics. I gave up, then got this video recommended.
You've made my day - thank you so much, and God bless.
You can't imagine how bothered I have been by this topic.
Literally spend a good 20 hours a few months ago watching videos related to electricity and electrons just to understand this.
Two days ago I decided to revisit and started to watch some more videos. Now i have a better grasp of electricity and electrons and with this video I finally feel like I understand the fields.
the combinations of words I looked up are staggering. even asked GPT and got the packaged mathematical shortcuts that only cause confusion
Thank you! I’ve been trying to understand electromagnetism but the relationship between electric fields, magnetic fields and radiation didn’t make sense intuitively. Now it does. Please keep up the good work by illuminating misconceptions and limitations of conventional explanations.
The best thing about this channel is that it's all I could hope in terms of the ability to conceive what's reallly going on from the POV of another person who hears things like "electric and magnetic fields create each other" somewhere else and go oh really? that seems like an important insight, ie we could invent things off of this, only to find out no, this was something someone who couldn't think properly heard or assumed and propagated. Same thing with the particles being waves that do normal wavey things. I hate all the "woooo it's so mysteeerious" aspect of everything. It's cool enough as it is, and we have these people in the field that have been told you just need to do your homework and you'll get to the top of the class, when really what we need is clean thinkers that cut through all the skaffolding our brain puts in to understand things functionally before we have a proper core-based intuition. Your work gets to to that "past the skaffolding" level, and so many of the top science youtubers have just become outlets of the textbook and the textbook's shitty examples and explanations. I hope you keep it up, I keep checking back for more!
reflected tone
Incredible video, I subscribed. You put a lot of time in effort into your work I can tell.
at 17:00, do these electric and magnetic fields oscillate in any way as the ripple propagates outwards? Like, doe the direction of these fields change or anything, or why is light normally conceived of as having oscillating fields?
When I was in school, I asked a lot of my professors about electromagnetic induction and never really got a straight answer. The response typically sounded something like this:
"A changing electric field creates a magnetic field (Ampère's law) and a changing magnetic field creates an electric field (Faraday's law) , so electric and magnetic fields are the same; an elecro-magnetic field."
I was never content with this "explanation". My questions were either being brushed off, or more likely, the professors didn't know the connection between electromagnetism and length contraction (relativity). It wasn't until I was taking a grad-level class on microwave circuit design that my professor tipped me off to the connection with relativity.
But according to Amperes law, it just enough that there's current flow for magnetic field to appear. If I understand currently, electric field doesnt have to change and we have magnetic field around the wire with a constant current flow.
This video tried to correct the picture that one has when introduced about EM waves, the textbooks saying changing electric fields creating magnetic fields and so on sometimes paints a picture that is bit misleading and creates unnecessary struggle for the subject.
At 4:15, E and B are synchronous ONLY for perfect plane waves; these waves are essential for Fourier composition but are entirely unphysical since they extend infinitely in both space and time and thus require infinite energy to create. Don't take metaphors too far or you will be disappointed. At 5:00, though PHOTONS don't interact in VACUUM, EM fields do interact by adding to each other. But just like sound, water surfaces, and every other wave neither deflects the other. At 6:15, there ARE particle beams in electron microscopes, cathode ray tubes, and particle accelerators that do NOT have cancelling opposite charges, so once again I call B.S. Three is my limit...
Hello everyone!
It seems like this video has gotten a flood of recent activity, (a bit surprising since it's three years old, but a welcome surprise) and I just wanted to, first, say "hello" to all you new people. Great to see you. And, second, it seems like there's been a sort of new wave of reactions, some negative some positive, to the content of this video so I just wanted to, in a central place, maybe provide some important additional context and discussion. Namely:
1) The human mind thinks in "concepts" but ultimately a physical theory is not a collection of concepts but a collection of math, math that either does or does not match experimental data. And within math it is possible to have so-called DUALISMS. A mathematical dualism is when two sets of equations on the surface look very different, but when you mathematically manipulate them in a certain way you find out that they are actually EXACTLY the same bit of math. Whenever you have such a dualism it is thus the case that ANY and ALL predictions of the one set of equations will be exactly the same in the other, again, because they're secretly the same bit of math, just in a different form.
2) The central set of equations of the classical theory of electromagnetism is often said to be what are called Maxwell's equations. However, these Maxwell's equations have a couple alternative formulations that can be shown to be mathematically DUAL. Thus, any such formulation will exactly make the same predictions and there is no basis for saying one is "correct" and the other is "incorrect" as they are secretly the same thing.
3) One such mathematical dual formulation is what is called a formulation in terms of "retarded potentials" (retarded meaning slowed or time-delayed):
en.wikipedia.org/wiki/Retarded_potential
4) The content of this video is basically just introducing this "retarded potentials" approach to people who may not be familiar with it. This approach should be covered in any good undergraduate textbook on electrodynamics, and is certainly not in any way "my" idea. I am not Lienard, Wiechert or Green, those were the ones who came up with it over a century ago. There also seems to be some notion that this formulation is "fringe". That is definitely not the case, as I said, the content of this video will also be found in any good undergrad textbook, for example, my personal (and I'm sure many others) favorite Introduction to Electrodynamics by Griffiths.
5) When learning a new subject, not everyone "clicks" with the material in the same way and having alternative conceptual and mathematical formulations can be of great benefit to some in learning. If you personally prefer the Maxwell formulation and find it intuitive, then "great!". If you've always found it a bit opaque, well then here's an alternative formulation that, again, is ultimately identical (i.e. mathematically dual) but may "click" a bit better.
6) As many have pointed out, this approach does not carry to a quantum mechanical treatment, but neither does Maxwell's equations and one CAN formulate quantum in a similar way, this is in essence what a so-called Green's functions approach is.
Anyways, hello again to all you new people. Please check out some of the other videos and welcome.
@@atomsandsporks6760 checkout Veritasium’s recent “misconception” video. It spurred a lot of activity. ElectroBoom’s reaction to Veritasium is most enlightening (pun intended).
@@atomsandsporks6760 You can write your comment as a top-level reply to your video and pin it. It's currently in an odd place, because you don't actually answer the objections of the person you're replying to.
@@atomsandsporks6760
My take on this is social engineering propaganda intended to dumb down the scientific population, such as,"Energy doesn't flow through wires", and, "Power is delivered through EMF passing through the dialectic and return". Something to do with Poynting's Vector. My question is then, 'What role do PCB traces play in a circuit?"
You clearly don't present the same material as the SJWs so you've become a target. Time for a response?
czcams.com/video/bHIhgxav9LY/video.html
@@atomsandsporks6760 Hi to your too, and many thanks for these posts and videos. Your approach is really helpful and it is nice to see an attempt at "correct" explanations (consistent and based on more modern models of what is happening). I was particulary inspired by the presentation of EM fields and the point you made that you really don't have one without the other (E or M) - hence "electromagnetism" is the force :-) (much like spacetime). It really drives home that the motion of a charge in space creates a "disturbance" (wave) in the EM field and the acceleration of the charge radiates EM throughout the field (which fills spacetime). This helps with the conceptualization of how the mechanical energy of a prime mover (turbine, etc.) in a generator delivers power via EM from one place to another. It also reminds us that when we are not at absolute zero, everything is going to "giggle" at least a bit (have some temperature) and "glow" with at least some EM (radiate some energy into the EM field). I actually think some discussion of power generation and transmission (with respect to EM) might be nice and help point out how energy and power flow in basic systems and how the load on such systems uses the them, with respect to EM fields would be really nice. Bottom line - showing the coupling between moving charges (and the effort to make them move) and EM waves that "are" energy and have the power to move distant charges is important.
This seems insightful, and I'm still mulling it over, but I must admit I am disturbed by the sweeping statement "This is how all E&M works". Surely this only describes classical E&M at best, not quantum phenomena (where we can't consistently determine properties like position and velocity which are crucial to this video's perspective). And of course, in our deepest and most accurate theories of the universe, Quantum Electrodynamics and Quantum Field Theory, the fields themselves are considered to be the fundamental physical entities, and not the particles (which are merely excitations of the fields). This seems to be in contrast to the perspective of this video, which maintains that the particles (and their classical properties) and the fundamental objects, and the fields are merely a "mathematical bookkeeping device". So I must conclude this is just a other one of many mental models, which may prove useful in understanding nature in some cases, and will fail to predict her in others - just as all of our human models do.
Hello everyone!
It seems like this video has gotten a flood of recent activity, (a bit surprising since it's three years old, but a welcome surprise) and I just wanted to, first, say "hello" to all you new people. Great to see you. And, second, it seems like there's been a sort of new wave of reactions, some negative some positive, to the content of this video so I just wanted to, in a central place, maybe provide some important additional context and discussion. Namely:
1) The human mind thinks in "concepts" but ultimately a physical theory is not a collection of concepts but a collection of math, math that either does or does not match experimental data. And within math it is possible to have so-called DUALISMS. A mathematical dualism is when two sets of equations on the surface look very different, but when you mathematically manipulate them in a certain way you find out that they are actually EXACTLY the same bit of math. Whenever you have such a dualism it is thus the case that ANY and ALL predictions of the one set of equations will be exactly the same in the other, again, because they're secretly the same bit of math, just in a different form.
2) The central set of equations of the classical theory of electromagnetism is often said to be what are called Maxwell's equations. However, these Maxwell's equations have a couple alternative formulations that can be shown to be mathematically DUAL. Thus, any such formulation will exactly make the same predictions and there is no basis for saying one is "correct" and the other is "incorrect" as they are secretly the same thing.
3) One such mathematical dual formulation is what is called a formulation in terms of "retarded potentials" (retarded meaning slowed or time-delayed):
en.wikipedia.org/wiki/Retarded_potential
4) The content of this video is basically just introducing this "retarded potentials" approach to people who may not be familiar with it. This approach should be covered in any good undergraduate textbook on electrodynamics, and is certainly not in any way "my" idea. I am not Lienard, Wiechert or Green, those were the ones who came up with it over a century ago. There also seems to be some notion that this formulation is "fringe". That is definitely not the case, as I said, the content of this video will also be found in any good undergrad textbook, for example, my personal (and I'm sure many others) favorite Introduction to Electrodynamics by Griffiths.
5) When learning a new subject, not everyone "clicks" with the material in the same way and having alternative conceptual and mathematical formulations can be of great benefit to some in learning. If you personally prefer the Maxwell formulation and find it intuitive, then "great!". If you've always found it a bit opaque, well then here's an alternative formulation that, again, is ultimately identical (i.e. mathematically dual) but may "click" a bit better.
6) As many have pointed out, this approach does not carry to a quantum mechanical treatment, but neither does Maxwell's equations and one CAN formulate quantum in a similar way, this is in essence what a so-called Green's functions approach is.
Anyways, hello again to all you new people. Please check out some of the other videos and welcome.
But in QED, the fundamental field is the four vector potential, which is why it is a so called minimally coupled (the charge part) vector field (the A part), electric and magnetic fields don’t really come up in the S matrix.
I really enjoyed the video. But how do we know that the velocity and charge information travels at the velocity c?
Can you explain the significance of having the fields/force depend on acceleration when usually they depend only on position and velocity. Do you need 3 initial conditions( r0,v0 and a0) to solve a problem?
Thanks for the very interesting explanation!
Is this using special relativistic EM interpretation or just rely on the original Maxwell's equations?
And what about QED? I thought E and B are just apparent measurables of the same thing, so they are just emergent properties of the underlying changing quantum fields.
Hello everyone!
It seems like this video has gotten a flood of recent activity, (a bit surprising since it's three years old, but a welcome surprise) and I just wanted to, first, say "hello" to all you new people. Great to see you. And, second, it seems like there's been a sort of new wave of reactions, some negative some positive, to the content of this video so I just wanted to, in a central place, maybe provide some important additional context and discussion. Namely:
1) The human mind thinks in "concepts" but ultimately a physical theory is not a collection of concepts but a collection of math, math that either does or does not match experimental data. And within math it is possible to have so-called DUALISMS. A mathematical dualism is when two sets of equations on the surface look very different, but when you mathematically manipulate them in a certain way you find out that they are actually EXACTLY the same bit of math. Whenever you have such a dualism it is thus the case that ANY and ALL predictions of the one set of equations will be exactly the same in the other, again, because they're secretly the same bit of math, just in a different form.
2) The central set of equations of the classical theory of electromagnetism is often said to be what are called Maxwell's equations. However, these Maxwell's equations have a couple alternative formulations that can be shown to be mathematically DUAL. Thus, any such formulation will exactly make the same predictions and there is no basis for saying one is "correct" and the other is "incorrect" as they are secretly the same thing.
3) One such mathematical dual formulation is what is called a formulation in terms of "retarded potentials" (retarded meaning slowed or time-delayed):
en.wikipedia.org/wiki/Retarded_potential
4) The content of this video is basically just introducing this "retarded potentials" approach to people who may not be familiar with it. This approach should be covered in any good undergraduate textbook on electrodynamics, and is certainly not in any way "my" idea. I am not Lienard, Wiechert or Green, those were the ones who came up with it over a century ago. There also seems to be some notion that this formulation is "fringe". That is definitely not the case, as I said, the content of this video will also be found in any good undergrad textbook, for example, my personal (and I'm sure many others) favorite Introduction to Electrodynamics by Griffiths.
5) When learning a new subject, not everyone "clicks" with the material in the same way and having alternative conceptual and mathematical formulations can be of great benefit to some in learning. If you personally prefer the Maxwell formulation and find it intuitive, then "great!". If you've always found it a bit opaque, well then here's an alternative formulation that, again, is ultimately identical (i.e. mathematically dual) but may "click" a bit better.
6) As many have pointed out, this approach does not carry to a quantum mechanical treatment, but neither does Maxwell's equations and one CAN formulate quantum in a similar way, this is in essence what a so-called Green's functions approach is.
Anyways, hello again to all you new people. Please check out some of the other videos and welcome.
Maxwell's equations are relativistic. In fact it's the relativistic nature of Maxwell's equations that lead to Einstein developing relativity. So there is no separate "relativistic formulation" of E&M.
What happens if a electromagnetic field overlap? Does this quantify the electricity? Im asking in regards to rTMS. I moved my head during treatment and i wonder if i got double electricity
Question: How does this perspective relate to the impedance of free space, which establishes the ratio of E to H for electromagnetic radiation?
You know, I'd love if you could make a follow up video to get better grasp on the math of the LW rulw.
17:45 In your blog post, you mention that the EM field strength due an accelerating or decelerating charge decrease at 1/r (this in contrast to the 1/r^2 decrease of field strength due to a non-accelerating charge). Is this also the case for the "canonical" sinusoidal EM field which we've seen many times? Does the strength of a propagating sinusoidal EM field also die down? Such a field has been described as self sustaining, so that suggests that it maintains its strength forever. Is this true? And if so, it makes a sinusoidal EM field somewhat special. Or do they also die down?
A pure sinusoidal wave is known as a plane wave that exists for all time (both forward and backward in time) and for all space. As soon as you try to curtail it to a finite region of space or time it is no longer sinusoidal but instead combines many frequencies. This is the case for real em radiation. So, yes a plane wave goes on forever with no loss of intensity but real em waves are never plane waves and therefore may lose intensity with distance.
The energy in the EM (radiation) field does not die down, but it does "spread" with (radial) distance. as a result, it becomes less "dense". Because of its reduced density, we measure a lower strength (with the same instrument) at a point further. But if we were to add up the entire field at a distance, the energy would be the same. However, the space you have to cover to measure that becomes bigger and bigger as the field spreads. At an infinite distance away, you have to cover infinte space to "add all up" (intergrate it).
@@abdunnoerkaldine8511 this sounds like Gauss's law...?
I like your videos. I hope your channel grows so that you can make more videos. Are your gradient symbols upside down? I am talking about the signs in 2:10 when you start talking about changing E and B.
It's actually not meant to be a gradient symbol, just a regular capital delta, as in "change in". So "change in E" -> B and vice versa. However, that being said, I foresee all kind of typos and typographical errors in my videos going forward! I'm usually pretty bad at spotting stuff like that while editing.
@@atomsandsporks6760 Thanks for the clarification. :D
Question: @10:46 how does point A know the position of the orange dot? How does a point know distance to the other point? Is it that charge only comes in discrete amounts and its off that that a particle can ascertain distance?
1:25 why do you say left and right but the arrows also show the image of right and left??
Does it explains the lorentz force? field up for magnetic momentum in magnets far away ( N--> S) and close to current (S-->N) ? This is incredible,thanks.
All in line with Maxwell as I see. I just missed this part with acceleration. Moving charge with constant speed also make magnetic field. Can you explain bit more this part about magnetic field at distant point?
en.wikipedia.org/wiki/Li%C3%A9nard%E2%80%93Wiechert_potential#Field_computation
I think the "ugly" equation he showed was only for electric field. On the wikipedia page above, you can see the ugly equation for magnetic field, which accounts for the non-accelerating component of B-field.
Is 10:38 similar to the biot-savart law for magnetism? In the sense that if ds (length of charge/element) X r (position vector to A) is 0 then there is no B
Visualisation of em vawe in most books is wrong. You are right, both E and B are shifted to each other.
This is well articulated---really enjoyed it!
Very interesting. I've also wondered a lot of the topics you mentioned such how two light beams can just pass through each other and not effect one another under the principle that changing field induce the other field
*affect
I have a similar question. How can the electromagnetic waves of a light ray move in one direction, instead of scattering in all directions? Does such an interaction between electric field vs magnetic field have some kind of mechanism to prevent it from branching into different directions? If this can be answered, probably it can also explain why two light beams can pass through each other without any deviation. This question has bothering me for a long time. Could somebody help answering it, please.
My understanding is if you move a charge around, a ripple in the EM field propagates outwards in all directions, and that's what an electromagnetic wave is, and that's what light is. Not sure where the particle view of light fits into this. Also not sure how photons fit in, and how atoms emitting or receiving photons alongside their electrons changing energy states fits in.
Here is an incoherent jumbled mess of questions. I guess at some point the wave collapses into particle like behavior, but like, is that the thing that violates time? (I doubt that's the part that violates time as in the quantum eraser experiment, but how can a wave that's propagating outwards in all directions collapse into particle like behavior once it runs into something and act like it was a particle moving in that one direction the whole time? I guess that's the point.. light is weird). It's weird that a wave would propagate in all directions, but the particle view of light is only in one direction or something. Not sure how multiple devices can pick up on these WIFI waves too.. like the waves are continuously being generated. Not sure if any of these outwards rippling waves collapse into particle like behavior, etc, and if they do, how can devices that are further away receive any signal if the wave already collapsed into a particle when it hit the closer device? Also based on a stack exchange answer with 100+ upvotes, it seems the word photon is poorly defined and means different things based on context.
The quantization of (anything) is another issue entirely. It applies not only to EM fields, but things like electron density waves.
Re wi-fi: the 2.4GHz E-M wave is a _huge_ wavelength. There are countless vast quantities of photons, and you can consider them spraying out in all directions. But really you don't perceive quantized behavior at this scale, any more than you care about Planck's Constant of angular momentum when you turn your head. It's continuous down beyond your precision of being able to measure it.
Really nice explanation. Very easy to follow, just the right pace, great graphics. But one thing you didn't mention is 'the photon', how does a photon fit into this understanding? thanks
Well... I believe I can cover that. It's really quit elegant as well. The "updates" are probably waves, there are only so many photons produced per second (and so per wave update), and the probably of finding them is determined by the wave produced when the field is updated. When the wave front covers a larger and larger area as the wave spreads further and further, the area the finite amount of photons could be does as well, which illustrates the weakening wave as it travels further from the source!
This on need to know basis, and you do not need to know if you would, you would read a book or two. You know how to read, don't you?
Very interesting video! I do question one thing if these formulations give equivalent results why are you so sure that one is more fundamental in terms of physical nature. That is why are you certain that that E and B are just mathematical tools whereas Jefmenko's formulation tells us something more fundamental about the universe. Could it not be the otherway around?
In fact historically before Maxwell E and B were thought of as nothing more than tools describing action and distance, before Maxwell "fixed" Ampere's law and saw them as a natural phenomenon rather than simply a tool.
Is frequency the rate at which the electric and magnetic field oscillate at a given point? And this is determined by I guess how fast a charge particle oscillated or whatever in the past?
Great video. Thanks for creating it. I have a somewhat related question. Why does changing magnetic field give rise to electrical current? I know it has to be so, it has been proven experimentally, and Maxwell's equations describe it. However, what is happing in the conductor at the atomic level to make the electrons move in response to the conductor's relative motion to the magnet? I have scoured the internet for a while but haven't found a satisfactory answer, except that it is just so. I will appreciate any help in understanding this phenomenon. Thanks.
Ivor Catt & Forrest Bishop have the best info on electricity.
I find this video totally confusing. Please correct me if Icm wrong. Thinking in photons appears much more easy to me... In conductors a current flows when there is an imbalance between the poles' electron concentration as same charges repel each other to achieve a minimal energetic state see chaos theory and bring the understanding of that in line with entropy and resulting probabilities. When an electron approaches a proton, it emits a photon. This happens continuously while the electrons move to high entropy states say fixing the imbalance. When photons interact with electrons in the vicinity of protons they kind of move away the electron from the proton "farther" as they take up the energy of the photon and thus the attraction force of the protons becomes negliable in relation to the kinetic energy of the electron. As a current flowing as outlined above causes quite chaotic radiation of photons, those photons will effect other electrons which is being described as an electromagnetic field. This in turn causes the same effect over and over again... I don't know how they teach physics in the US, but here in Germany we were made aware of the differences of an electromagnetic and a static magnetic field. Maybe you should have done so, too, because I don't have a clue what you're talking about after watching this video...
So you have a minor mistake at 6:00. If you start moving the negative line charge, it will Lorentz contract and make a negative charge on the “wire”. Rather, you need to accelerate individual charges a la Bells Spaceship Paradox so they remain with constant spacing in the lab frame.
This means that in their own frame at speed, they will spread out by the Lorentz factor gamma (the string in the paradox breaks). Moreover in their final rest frame the protons will be contracted by gamma, for a total charge density factor g - 1/g = gamma X beta….which works with the LT of E and B fields.
Your theory is pure gold.
I think the traditional Maxwell's Equn's throw up red flags because they are Classical (non-relativistic) like Newton's Laws of Motion, but they break Classical physics as it produces a speed of light that is constant for all observers. So it is not a fully Classical theory, but it totally misses out on the Relativistic viewpoint where there is only one kind of field (not separate E and M) in 4-D spacetime.
So, it works very well for many practical applications and allowed the understanding needed to invent radio, for example. But even when applied in situations where non-relativistic physics should be OK (i.e. participants are not moving quickly relative to each other), it doesn't _quite_ work out. Even at hand-held speeds, a moving magnet gives different physical effects than a moving coil, when Newton would have it that we can't really tell which one is moving and either viewpoint is correct and gives consistent answers.
Remember, Einstein's famous paper introducing SR was called _On the Electrodynamics of Moving Bodies_ and solving this issue is what it was really about.
Fun experiment with a homopolar generator: A metal disc spinning in a magnetic field create a voltage from centre to edge. Now stick magnets to the disk and spin it, same voltage
No, Maxwell's eqs. are fully relativistic. And I challenge your assertion that you can tell which one is moving in your "hand-held' speed thought experiement.
Maxwells equations are perfectly relativistic. Whats not relativistic is the assumption that is sometimes made when solving some electrodynamics problems naively that if some charge distribution has some length L then it will still have a length of L when its moving. But that has nothing to do with electrodynamics, rather with the fact that you aren't modeling that charge distribution (matter) with the correct model that is relativistic and thus have to artificially account for that.
They are not manifestly relativistic, but they are relativistic and do come in manifestly relativistic form, something like dF = J, which says exactly what this video says: 4 currents source a bi vector field
I have a bit of a problem with the way you described the electron sending out information about its velocity and acceleration. The electron has no way of 'knowing' its velocity, not to mention transmit that information. I think it would make much more sense to assume a resting electron and a moving point A. That way, you only need to know the magnitude and direction of the electric and the whole velocity/acceleration information is just stuff the point A experiences as it moves though the field. Or am I missing something here?
Anyway, great video!
I just don't understand why the electric field doesn't point in the direction of the time delayed position in the first place. If the electric field is radially emanated outwards the charge, why it gets deflected when it reaches the point A. It should have a perpendicular angle with that yellow circle, shouldn't it?
Same question man
The transverse emanations of a charge's electric field are due to that charge's acceleration. The reason for that is because the electric field of a charge is squished in the direction it travels, so if you change its velocity, you change how much its electric field is squished. However, since its electric field squishing is delayed, transverse electric fields are required to keep its electric field lines continuous. These electric fields lines need to be continuous because the only place where they can be discontinuous is at other electric charges which are lacking in our example.
Same question
@@ayoutubechannelname what?
@@arnesaknussemm2427 www.compadre.org/osp/EJSS/4126/154.htm
This is called "Philosophy of Science".
Thank you very much Sir for this. I wish you grow more and more with this rich content of yours reaching more masses.
I believe, David J. Griffiths would be pleased watching someone presenting this is such a nice manner.
Regards
Sandy Check: LW RULE CANT ONLY APPLY to one light wave affecting itself later in time. However, to do so means electric fields INTERACT ( even if only with identical wave formations). When interacting they can produce a magnetic wave (the LW Rule invalidates your claim the ligh is not able to interact with light. And electric fields (moving or accelerating) do not create magnetic fields.
Experience with linear accelerators indicate the electric fields must be aligned to produce measurable magnetic fields. Possibly also the same waveform. Magnetism may be required to have a limited angle of separation of the electric fields.
Interesting. I'd be interested to see your analysis of the Aharonov-Bohm effect using this model. And then on another tangent, an analysis of the Tom Bearden MEG, which if you research it, he claims that it uses this effect entirely in its ability to operate as a "very efficient" transformer.
It uses a Honeywell Metglas Amorphous C-core (AMCC-320, I believe). That laminated core has a very high magnetic permeability. If you put a permanent magnet into the center of this core (you'll have to check a video of the replication of the MEG and the diagrams since it is pointless to try to describe the geometry with words here), it will contain the entirety of the magnetic B-field, but the A-field (electromagnetic vector potential) is claimed to still exist in the space around the magnet that the B-field would be in if it was not contained with the Metglas core. This effectively "decouples" the E and B fields from each other (with the A-field being the electromagnetic four-potential which they are both derived from).
Perturbing the A-field alone (which is in the space around the coil) will actually induce an E-field in coils wrapped around this transformer. Because the B-field is contained entirely in the core, it does not interact with the E-field and therefore does not have the usual losses associated with a typical transformer design (where the magnetic field works against (counter-balances) the induced electric field).
This is a naive explanation of how it works. It is not meant to be rigorous here, because I am not a physicist. There is plenty of info out there on CZcams and in the US patent for this device (patent number US6362718B1) to build it and understand the inventor's explanation of how it works. He explains the observed effects as being related to the Aharonov-Bohm effect experiments. But an "infinitely long solenoid" is not necessary to isolate the B and A fields. Because the laminated metglas material and the geometry of this device does this for you.
I am not a physicist, so I probably have terminology wrong here. The research on this device is properly rigorous, though. I think your model that you describe here will shed a new light on how this device works, and possibly be a more "acceptable" explanation to mainstream physicists.
Thank you
Paul
PS: It would also be interesting to reconcile your model with general relativity given the time-delay aspect of your model. Or perhaps you have a different explanation for observed relativistic effects.
I really like this explanation, am taking a course on electomagnetism at a community college right now and this video has a lot of the intuition I've been missing
Ya, this "retarded potentials" (retarded meaning "time-delayed") is something that's maybe given a mention in most electromagnetism textbooks but often doesn't get the time it deserves. I've also always found it quite intuitive. Glad you liked it!
I'm confused by what's happening. How does the time delayed position information differ from the LW predicted field? Why would this create a perpendicular magnetic field.
I'm just not seeing the cause and effect of this reaction. Can anyone clarify?
Excellent explanation. One doubt though ... You said that the time delay of information at a point is because the the information takes speed of light to reach that point. But while deriving the speed of light itself , in any books the it is seen that the two fields causes each other and then the derivation is proceeded. And we get a number which is th light speed.
So can you tell how can you find the speed of light in the first place ?
Hello everyone!
It seems like this video has gotten a flood of recent activity, (a bit surprising since it's three years old, but a welcome surprise) and I just wanted to, first, say "hello" to all you new people. Great to see you. And, second, it seems like there's been a sort of new wave of reactions, some negative some positive, to the content of this video so I just wanted to, in a central place, maybe provide some important additional context and discussion. Namely:
1) The human mind thinks in "concepts" but ultimately a physical theory is not a collection of concepts but a collection of math, math that either does or does not match experimental data. And within math it is possible to have so-called DUALISMS. A mathematical dualism is when two sets of equations on the surface look very different, but when you mathematically manipulate them in a certain way you find out that they are actually EXACTLY the same bit of math. Whenever you have such a dualism it is thus the case that ANY and ALL predictions of the one set of equations will be exactly the same in the other, again, because they're secretly the same bit of math, just in a different form.
2) The central set of equations of the classical theory of electromagnetism is often said to be what are called Maxwell's equations. However, these Maxwell's equations have a couple alternative formulations that can be shown to be mathematically DUAL. Thus, any such formulation will exactly make the same predictions and there is no basis for saying one is "correct" and the other is "incorrect" as they are secretly the same thing.
3) One such mathematical dual formulation is what is called a formulation in terms of "retarded potentials" (retarded meaning slowed or time-delayed):
en.wikipedia.org/wiki/Retarded_potential
4) The content of this video is basically just introducing this "retarded potentials" approach to people who may not be familiar with it. This approach should be covered in any good undergraduate textbook on electrodynamics, and is certainly not in any way "my" idea. I am not Lienard, Wiechert or Green, those were the ones who came up with it over a century ago. There also seems to be some notion that this formulation is "fringe". That is definitely not the case, as I said, the content of this video will also be found in any good undergrad textbook, for example, my personal (and I'm sure many others) favorite Introduction to Electrodynamics by Griffiths.
5) When learning a new subject, not everyone "clicks" with the material in the same way and having alternative conceptual and mathematical formulations can be of great benefit to some in learning. If you personally prefer the Maxwell formulation and find it intuitive, then "great!". If you've always found it a bit opaque, well then here's an alternative formulation that, again, is ultimately identical (i.e. mathematically dual) but may "click" a bit better.
6) As many have pointed out, this approach does not carry to a quantum mechanical treatment, but neither does Maxwell's equations and one CAN formulate quantum in a similar way, this is in essence what a so-called Green's functions approach is.
Anyways, hello again to all you new people. Please check out some of the other videos and welcome.
When people say a changing magnetic field "causes" an electric field and vice versa, I don't think they really mean "cause". That word shouldn't be taken too seriously there; people are just giving a rough summary of Maxwell's equations. (I would not use such phrasing myself, though.)
Good video. There are a lot of subtle important pieces of information in this presentation. But I find the semantics difficult to follow.
I am confused about your claim re: interaction of electric and magnetic fields as "they don't interact with each other".
So for example, when a charge moves in a changing magnetic field, what then is mediating the motion of the charge?
The magnetic field is at a 90-degree angle because it is delayed by the speed of c. It would be in phase at zero degrees if it were in perfect unison.
Is magnetism the result that occurs when multiple eclectic fields collide (meaning the fields move)?
A photon wave-packet carries off M (angular momentum) to/from an atomic orbit change. Or does it?
So EMF perturbations ripple out in all directions like a wave if I'm understanding correctly.. where does the particle view of light fit into all of this?
Its fascinating science can be this simple yet complicated. After a long time I enjoyed electromagnetism. Thanks
At 16:42 the magnetic field is shown as a group of spikes, not a smooth curve. Is there some significance to this or was it just an arbitrary choice of how to graph the fields?
arbitrary
From your blog post linked in the description. "It turns out that in a radiating electromagnetic field the electric and magnetic fields are always perpendicular to each other and perpendicular to their direction of motion."
By direction of motion, you're talking about the direction of motion of the EM disturbance, right?
are they in step ? what if the time diff is too small for us laymen to measure?
this is different than how I was taught physics! it'll take a while to digest. Thank you.
Very interesting arguments and ideas. But, I don't agree for the following reason: Electromagnetic waves are solutions to Maxwell's equations in the absence of electric charges and currents. Therefore, electromagnetic waves exist in the complete absence of electric charge.
I have a question. I well understood how the waves are produced, and how the change in electric/magnetic fields aren't the main reason for it. But there are still expressions in Maxwell's equations implying these changes should have some effect on another, so even though those effects won't appear instantly (like you have shown as first suspicious notion), shouldn't they still have an effect on the wave in some way?
Around 16:09 you say it falls with a factor 1/R^2 and then you go on to say that it is constant. Am I misunderstanding something?
When discussing the radiating/non-radiating parts, did you mean intensity? Because wouldn't summing the energy around radiation spheres be constant?
Thank you for this video, you don't get many that get into knitty-gritty details while still being rather accessible (and entertaining). You mention early on that there is a misconception that the fields propogate each other - which is why they can continue for so long. Later you clarify that they have no effect on each other - but they still "radiate" together. Does this actually continue forever? Will light never slow down unobstructed - not even through something tiny that we cannot detect - just continuing forever?
With sound, it's the movement of air particles that continues, with waves it's the water particles. With electromagnetism... it's moving through nothing at ridiculously fast speeds? Is it not something tiny that itself is being rippled after the initial acceleration?
And if there is something tiny (tiny might not be the right word) - is that what causes the actual force of gravity - that tiny thing/lattice/field being "compressed" - or instead of a tiny thing - dimension(s) or intersecting parts of them? Thank you - Yasir. And also sorry in advance for, well, all of it.
simply brilliant. after a full evening of searching finally someone who gave me the tools to explain how the em-field changes from near field to raidiating far field.
I have often wondered why very few people fail to notice the obvious errors in reasoning. Even seeing as simple dipole antennas with changing voltages have an 90 deg out of phase current... and then suddenly they all show fully coherent electric and magnetic fields.... very odd.
many thanks!
The voltage and current in a dipole are in phase. When the votlages at the tips are maximum, that's when the maximum current is flowing.
What carries the signal or information?
It sounds like each electron (or charged particle for that matter) continuously broadcasts its position, velocity, and acceleration in all directions forever.
Do they?
Or is it more like each charged particle perturbs the field? And if we could isolate a charged particle's contribution to the electric and magnetic field at a point, then we could figure out that charged particle's past position, velocity, and acceleration?
That's my problem with this concept. It doesn't explain anything, because stating that a charge "broadcasts its position, velocity, and acceleration" is not explained. It sounds like another way of describing a field - which also begs for explanation, so choose your poison. How are these three variables "encoded", "transmitted", and "decoded", to use information-centric terms? And what about the value of the charge itself? Wouldn't that make a difference?
So the magnetic field is basically the phase/time difference between the instantaneous wave function and the electric field traveling at the speed of light relative to the charge in motion?
How then is the magnetic field weaker as we move away from the current? Is it perhaps then the inverse of the time difference?
Then what about permanent magnets? What causes those materials to exhibit a magnetic field?
The disputed statement is the stand of Classical electromagnetic field theory. And is backed by Maxwell's equations.
Excellent tutorial. I'll have to listen to this a couple of times but I find it amazing that it can even be figured out at all. If time dilation is included then I'd require additional time to let it sink in!
Where do photons fit into all of this? Atoms can accept or release photons at the same time as their elctrons move into different energy levels, etc.
I hope someday to understand how these features of a charge get spread from the charge to point of detection or effect.
the first 3min 20sec has me wondering if photons are just quasi-particles
Thank you so much for this video!! I love it when a video explains something I couldn't understand for so long. Before I had zero understanding now I have 1%. A big improvement for me. Now I have to work on learning the LW equations.
what application do you use to make these awesome videos?
After Effects (though I hate it) for the video compositing, Python or Matlab for simulations and Paint .NET for my feeble attempt at art.
I am an A-level physics student and I think i just had a stroke trying to watch this
The issue for me is that the spoken script does not match the text on screen. Trying to read the text in a matter of a couple seconds while following the narration does not make for a very good educational experience.
@@Uniblab9000 Hugely distracting for sure. Makes for missed information...
So wavelength/frequency is just how fast the field strength is fluctuating? And this is irrespective of the field strength? IE you could have a field strength starting at 5T or at .1T and the wavelength/frequency is only determined by how fast this field strength changes? So could a radio wave could span the field strengths from 5T to 5.1T or from .1T to .3T (this is all arbitrary?) and an x-ray could span the same range of field strengths? The X-ray would just span them more quickly?
Please clarify how your ideas relate to: (1) linear differential equations and the superposition principle for solutions; (2) Fourier analysis. I think this should make clear the role of sinusoidal waves.
THANK YOU! You're confirming several of the conclusions I had already come to (no help from standard E&M textbooks, or so many other physics videos).
Great presentation. Rather than just capping on light, how about detailing how EM Induction really works. Why/how Lenz’sLaw works and how a Flux capacitor (Tesla’s bifilar inductor) defeats this “Law” yielding induction without a reactance resisting the conversion of moving magnetic field into a changing voltage field to a moving magnetic field that inverts Lenz’s Law into a force amplifier.
OMG, the LW rule enables free energy production with capacitive inductors!!!
😅😊
So how does this look where an electron jumps from one energy level to another to release a photon?
The problem I've always had with moving point charge retarded potentials is that it's very intuitive, but as soon as you try to express even the basics in maths it becomes a nightmare, unless you've come across otherwise? A bit like the magnetic field associated with a circular loop of constant current - it sounds like it should be an easy calculation, but in reality it's a whole MSc programme.
This a brilliant and absolutely much-needed video. Can’t believe it’s been around for over four years and I just came across it! Don’t get down from what your criticizers say - there’s an extraordinarily large segment of science CZcams viewers out there who have a very poor grasp and the distinction between correlations and causations.
I still don't understand it. Where do photons go when there are no charged particles left ? like in the heat death of the universe when all matter has decayed.
In your example it doesn't look like a single sinusoid because the "flick" of the charged particle results in a multitude of superimposed sinusoids. This is physical and not just a mathematical concept; if you wanted to, you could isolate the sinusoids using a filter.
The specification that you don't measure fields, but observe interaction is crucial to understand what a field actually is. When you hear the quantum fields have borrowed the idea of fields from EM, some allarm bell should ring.
I have heard in the past that the magnetic field is the relativistic correction to the electric field. Does this sound correct?
Good day. There is a causal effect between variable magnetic fields and electrical fields. One creates the other.
16:36 wont velocity in the particle create the same bump.
I know constant velocity gives constant magnetic filed but.......
Lets say we have an observer at point p. If a charge with contant velocity moves away from him creating magnetic field.
For observer p , since the charge moves in the velocity opposite to him, wont there be change in magnetic field.
2:26 In always assumed (wrongly it seems) that as the magnetic field collapsed, its energy created a matching rising energy of electric field and thus they alternated. However, seeing the diagram where both field rise and fall *in unison* creates an issue for me because you clearly see a point or node where both fields drop to zero at the same time…implying there is nothing left to create the next rise. The wave forms have no mass to carry them on, so with both fields once depleted momentarily to zero…that is the end of the wave?
is it an interaction between electric ( magnetic) field or is it the interaction between an already existed electric (magnetic field) with an existing charged particle?
Nice work!
maybe I totally didnt get it but then- are emf sort of autonomously behaving traces or memories that also unpredictably reorientate in space from their initial broadcasting particle? and if they carry energy away from the charge, are they sort of redistributing energy in space then? a sort of energy space gardener or something?
Whoa! Why doesn't the moving charge (analogy of a beacon) lose energy if it is radiating an electric field and magnetic field? Does it only lose energy when it interacts with matter?