No, Changing Electric Fields DON'T Cause Magnetic Fields; The Real Origin of Electromagnetic Waves
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- เผยแพร่เมื่อ 20 ก.ย. 2024
- For a much more detailed discussion of the origin of electromagnetic waves, see this blog post:
atomsandsporks...
and, in general, be sure to check out the main website:
atomsandsporks...
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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 TH-cam 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).
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.
Brilliant work! Now I need to go pick up and reassemble the pieces of my mind so I can continue down this rabbit hole!
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.
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
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 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 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
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?
th-cam.com/video/bHIhgxav9LY/w-d-xo.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.
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?
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
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.
6:20 That is nothing like the field you get - it is circular and perpendicular to the path of travel.
The disputed statement is the stand of Classical electromagnetic field theory. And is backed by Maxwell's equations.
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!
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.
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 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
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
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.
Your video is counter educational, and will confuse people learning E&M for the first time. You show a far field conclusion, but discuss near field theory. If you started at Maxwell's equations, and set charges to zero, the equations still allow for fields. As to the tone of this video, it sounds like the old debates were people are trying to eliminate fields and have charge only E&M, which Wheeler I believe succeed with a cumbersome theory. But, it is possible as Dirac showed to cast the theory with fields only. Finally, your disregard of sine waves is bizarre: Have you not heard of Fourier analysis?
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.)
one of the most incoherent explanations((( but visuals are very very good!
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.
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...
I'm extremely confused, and Veritasium would argue that means I learned something. Cheers mate excellent discussion!
Thanks!... I think?
"Changing Electric Fields DON'T Cause Magnetic Field" - there is nothing wrong with saying that changing electric fields cause changing magnetic fields, and calling this statement a simplified model of emf wave propogation.
In alternating current used for utility electricity distribution it is clearly evident there are fluctuating magnetic fields. if we oscillate this alternating current close to the speed of light (if that makes sense) then you will get an emf wave , or a photon (again, depends on the model you use, that is, models which serve different purposes).
Why is the 'magnetic field vector' perpendicular to both the 'electric field vector' and the 'time-delayed vector', instead of the difference between them?
Electric FIELDS do not create a magnetic FIELD, but electric CURRENTS do, and vice versa. Don’t get them mixed up.
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.
I agree with you about 'suspicious notion #1' at 4:14. It is a misconception perpetuated by first year physics students. What is actually happening is that the energy of the photon is alternately transforming between electric potential energy, and magnetic potential energy. Look carefully at Maxwell's equations: the induced electric field is proportional to the rate of change of the magnetic field, and likewise, the induced magnetic field is proportional to the rate of change of the electric field. When charted, the two are 90 degrees different in phase.
bingo. He doesn't know about the curl.
This is called "Philosophy of Science".
This guy never learned Maxwell's equations. The first property of Mawxell's Equations is their linearity. Basically if A and B are two solutions of a linear system, then any linear combination of A and B is also a solution. This allows wireless communication. This video is the epitome of the Dunning-Kruger effect.
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?
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 TH-cam 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.
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.
Hello Mr Atom and Sporks. Thanks for the video which was extremely interesting, informative and different for a relative beginner in physics such as myself. John Lampe,sunny Perth,Western Australia.
Visualisation of em vawe in most books is wrong. You are right, both E and B are shifted to each other.
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).
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.
So if fields themselves don’t exist, what is the means by which the forces between charges are communicated?
Touché. You can certainly think of the fields as being real. In fact as one moves to the quantum mechanical description of electromagnetism that can't really be avoided. But rather what this Lienard-Wiechert reformulation tells us is that what all those fields are "holding" in terms of energy and, for lack of a better word, "information" are "echos" of particle action in the past. They themselves bring nothing to the table beyond holding those echos (again, this doesn't necessarily remain true in a quantum mechanical description)
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.
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.
The mistake was to refer to "charges" rather than "charged particles" the source of all electric charges is charged particles.
∇×E=-dB/dt and ∇×B=μ0ε0 dE/dt are the Maxwell's two laws in question (excluding the current term for the last equation). If we think about curl, if two nearby vectors are pretty much the same as each other, then there is small curl. If the two nearby vectors are very different from each other, we get larger curl. In the commonly taught version of EM waves where they create each other, here's the reasoning for them causing each other: As the B field goes from positive to negative, there is a larger curl because the vectors has a large change in magnitude. When the B field is maximum, there is low change in magnitude so the curl is smaller. There is basically a 90 degree shift between the B field and the curl of the B field. Since the rate of change of electric field is proportional to the curl of the magnetic field, the rate of change would be a scaled version of the curl but have similar form. If we integrate again, using the sine wave pattern, we get another 90 degree shift. Therefore, B and E are 180 deg shift. The same can be shown in the other equation.
No, the two angles you are referencing are with respect to different dimensions so do not sum as you describe.
@@jon9103 th-cam.com/video/W1cTpqM9DaU/w-d-xo.html
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!
So how does this look where an electron jumps from one energy level to another to release a photon?
You're getting confused between near and far field EM waves along with electrostatic fields. There is no coupling between electrostatic fields, but there is always a coupling between time varying E and H fields according to Maxwells equations. In the far field plane waves they are related by the characteristic impedance. In the near-field the relation is complicated by the geometry and can be very high order.
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 ur ass
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.
CORRECTION --> While every thing displayed on the video is exactly accurate except the shape of 'light' at the very end. For a very specific case when the charge moves in a periodic oscillatory closed path (i.e. having periodic acceleration) the electric and magnetic fields indeed become sinusoidal [see Ref]. At a large enough distance from such a charged particle (called its 'wave-zone') the EM radiation acts nothing but a plane wave spreading radially outwards. The frequency of its oscillation is same as the frequency of the sinusoidal EM waves. If light would not have sinusoidal shapes there would not be an electromagnetic spectrum with different types of radiation with their specific range of frequency (i.e. we could not distinguish Radio waves and ultraviolet rays without the information of a proper frequency/wavelength of them).
Ref -- 1. Chapter 9, Classical theory of fields by Landau & Lifshitz 2. Chapter 29 Feynmann lectures Vol. 1
I really enjoy all the quality videos of this channel. Especially this one made me go through the basics of electromagnetism again after a long time. Kudos!
You know, I'd love if you could make a follow up video to get better grasp on the math of the LW rulw.
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...
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 am always confused about time inside a photon being frozen. But photon is also a wave, I would assume a wave takes time to make. But there is no time inside a photon. So what gives?
In special relativity there's always 2 points of view 1) the POV of a person (or something) that is moving eg a photon 2) the POV of some1 who's watching. Each POV is a different version of reality. Both see themselves as stationary & see that the other person is moving. So eg I am on the sidewalk & you drive past at 30 mph due East. I see myself as stationary. I see you moving at 30 mph. You see yourself as stationary. It's like your car is on a treadmill. You see me moving at 30 mph due west. Both interpretations are valid. Due to special relativity you see my watch is ticking in slow motion & you see me a tiny bit thinner. I see you as thinner. (BTW all magnetism is caused by Lorentz contractions of electric charge = the charge gets packed in to a small space like sardines in a can). So anyway, from the photon's POV it's stationary & the universe is moving at c. At c the Lorentz contraction is at a maximum. Therefore the photon sees the universe as infinitely thin & frozen in time. However from our POV we see ourselves as stationary & the light's moving at c so takes 8 min to travel from Sun to Earth & the light has a frequency of say 1 million cycles per second so each cycle does take a little bit of time
After studying electrodynamics I also started questioning why people represent waves as sine curves. One reason may be the way we use light in our everyday lives. Radio stations and wifi use frequency bands of quasi-monochromatic radiation. But yeah I fully agree with you. The solution to 2nd order wave equations is any distribution f(r-ct) moving at the speed of light.
It’s the same reason why they compartmentalizations education and put mechanical oscillations separate from electrical oscillations.
Mechanical oscillations and vector scalar calculus. Would allow for electrical energy creation
If electromagnetic wave does not interact then how interference patern occur in two slit experiment?
(this is my current understanding, I'm still trying to figure it out better)
the waves don't interact with each other but they both affect the Poynting vector, (the time-average of which has the intensity as its magnitude)
the interference pattern is the result of the waves having opposing effects on the Poynting vector at the dark spots, and similar effects at the bright spot.
I think Maxwell would disagree with you, for him light was a real physical phenomenon, not a mathematical "information" apparatus made up of equations. That's why he introduced the concept of displacement current.
Maxwell may disagree with him( I'm not sure) But maxwells equations certainly agree with him.
@@JensenPlaysMC Not at all. Without reading Maxwell and (mainly) Heaviside is impossible to understand Maxwell's theory.
@@nathanneiman Jefimenkos equations states that Charge density and current density produce the E field and B field. in this form it is clear that E and B fields Don't create one another. The current and charge density does. The E and B field aren't separate fields let say, They are actually one field
@@JensenPlaysMC Maxwell never said that E field creates H field without charges or currents, (B field actually is the magnetic flux density), on the contrary he proposed the existence of displacement current.
@@JensenPlaysMC Energy can be stored in a medium (including vacuum) by means of an electric field or a magnetic field. In the same way it is possible the existence of an electric field without a magnetic field and vice versa. Hence there are two distinct forms of energy, electric energy and magnetic energy. In turn, the medium has at least two distinct physical properties, permeability and permittivity.
Sir, if I got your explanation correctly, a photon is the signal of an acceleration of a charge in the past. Each acceleration is finite and the photon is finite. The speed of light is the speed of transmission of that signal. Relativity and electromagnetism are deeply related. Einstein got a Nobel for the photoelectric effect but famous for his theory. It also makes sense here why he went from one to the other.
As you have seen this video recently and I have just seen it today and the video is at least 4 years old I would like to discuss some of it with you. The presenter I believe was making some remarks only a year ago but I am not so sure that he will come back.
I believe he is correct with some of the statements in the video but I am not too happy about some of them too. I believe radiation (light, radiated heat and radio signals) is a fluctuation between an electric energy and a magnetic energy. I base that on that I believe that to be what is radiated from a dipole antenna. I base that on that a current is running in a dipole and an electrostatic charge is created between the ends of the dipole when we transmit a signal. They are of cause fluctuating with the frequency of the transmission. The current in the dipole is creating a magnetic field or ring around the dipole. This field must be the strongest when the current is the strongest and that is the time the electroctatic field between the end is at it's weakest. The dipole is oscillating.
I have been told recently that this is correct for the near field but not for the far field. I can not understand that as to my knowledge it is for any other wave like a water wave and a sound wave. Current flows the fastest when the pressure is the lowest and stops at the wave tops. That is basically also what is said in this video. What is possibly confusing peopleis that current and magnetism is in phase.
What was also said in the video I believe was that there was basiccaly no magnetic field at some distance from the transmitted point. I believe that to be incorrect as radio signals can be received just as well on a mognetic antenna as on an electrostatic antenna. That is the second reason for believing that the radiated signal is a fluctuasion between magnetic and electrostatic forces.
A third reason is the conservation of energy. Any energy transmission I know of has a constant transfer of energy until it is taken away. In a pure resistive circuit the energy does fluctuate with the wave form of the electrostatic energy but a dipole antenna is not resistive. It is reactive.
Looking at it that way the energy must be flowing constant I believe. That also infer that a photon can not excist exept as an ammount of energy over a time period. That is ok as there are alternative theories that make it the frequency of the radiation that makes electrons jump in an atom.
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?
Even though almost finishing my master degree in physics, I was completely caught up in this misconception!
Thank you so much for pointing out this misconception !!
Did you study the special relativistic treatment of electromagnetic fields?
This (9:00) means that any charge traveling at less than the speed of light will encounter its own magnetic & electric fields as created in the past. Doesn't this field alter the trajectory of the charge?
If field detectors (or as he'd say, charge containers) are false advertizing and only charges can be affected by the time-delayed electromagnetic fields, how come electromagnetic waves travel through vacuum? Any idea???
I'm just worried about the adverse health affects of alternating electro-magnetic fields emmited from high-voltage power lines and the quest to comprehend what it even was led me here... Damn, now my brain is confused as hell!
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!
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.
Its fascinating science can be this simple yet complicated. After a long time I enjoyed electromagnetism. Thanks
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.
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!!!
😅😊
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.
I do find this inconclusive and I don't get the point of this clip.
firstly at 5:00: electromagnetic waves do not interact, because they are but photons. Though photons are bosons and bosons don't correspond to the Pauli-Principle so it is possible for a system of two bosons or more to be in the same quantum state, since the wavefunction does not change the signs, what is called symmetrics ( by the way a system of two isolated electrons out of an atom can add up their spin to 1, thus becoming bosons, which would therefore account for the interferences with the double-slit-experiment...)...
and secondly:
the time delay of the em-wave-message is expressed by the sinusoidal shape of the waves, cause if there wasn't a delay it would be a flat line and no wave...
The causation between electric and magnetic fields can be found in the equations Maxwell came up with and there is non argumentation in here, why they could be wrong. It is just claimed that they are wrong indeed without even mentioning them!
The second equation stipulates that there is no geometrical source in any given point ( therefore the 0 at one side in this equation... ) but a source for there emergence there must be nonetheless.
The fourth equation stipulates unanimously and unequivocally the causation of an magnetic field by an electrical field if it experiences any class of differenciation and in the clip this is turned down suggesting a mere coincidence between both fields but it is refused to explain for the source that as a consequence one need to account for.
Le p'tit Daniel🐕🏒🍔🍟
What I learned........
Phase 1. Collect underpants
Phase 2.
Phase 3. Profit!
Very good! I agree that the "causality" concept is not correct.
I think this is only partially correct in the sense that electricity is created by the pulse creation and subsequent inertial interaction between magnetism and dielectricity ( the stuff that makes capacitors work) This inertial interaction is what results in what we call electricity and is resultant from matter ( the point source) , the macrosource (dielectricity), and the Aether is ( the substance which Mendeleyev wanted to call Newtonium) . That which fills up empty space. Space being just that i,e. space. ( The idea of a wave can be imagined as a visible series of pulses radiating outwards through the aether in three-dimensional form which , if our eyes could pick up that frequency, would look like a rapidly expanding ball. If one could cut this ball in half the frequency might look like a wave form , the dielectric enlarging with the radius and the magnetism diminishing with the radius.
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?
In the case of the solar wind, the ion is about 18x the mass of the incoming electrons, so even though the electric force is equal, the electrons are grabbed and dragged behind the ion.
I think we need to go back to 1/r² and the three dimensional physics of the Inverse Square Law! Spherical 4πr² geometry is fundamental to this process and this is based on Huygens’ Principle of 1670 that says,
“Every point on a light wave front has the potential for a new spherical 4πr² light wave".
The spherical interior is naturally 3D and we can think of each point on the curvature of the wave front as a potential photon ∆E=hf electron interaction as vibrations forming resonance. The spherical 4πr² surface forms a 2D boundary condition or manifold for the uncertainty ∆×∆pᵪ≥h/4π of everyday life.
If electric fields aren't caused by charges, then how come in Gauss' Law any charge (even when stationary) within an enclosed area has an electric field? I can sort of get behind the magnetic field thing (I know they are created by moving charges, which have a velocity and/or acceleration).
I think you may have misunderstood me. Electric and magnet fields are definitely caused by charges and their motion. The central crux of what I'm saying is that one can formulate (classical) electromagnetism where any and all fields are EXCLUSIVELY the result of a charge doing a thing (i.e. velocity or acceleration) in the past. This formulation is called the "retard potentials" approach to electromagnetism, or the Jefimenko (or Lienard-Wiechert) equations, if you want to Google further. So every electric and magnetic field that exist, in this picture, is just carrying information of the time-delayed history of charges and their motions and the fields themselves have no great meaning, beyond this. Though I should point out that this formulation of electromagnetism gets a little pricklier when quantum mechanics gets involved. However, the key point of the video is that fields have no interaction with each other or any causative relationship, they are oblivious to one another, and they are in fact SOLELY the result of charges.
5:00 Current in a wire generates zillions of changing E fields (dipoles) as electrons move relative to nuclei.
Hate to tell you, but a changing E field (with a constant rate of change) does indeed induce a static and circular B field.
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 TH-cam 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 must have misunderstood something here: Do you really mean that the field of a non- accelerating charge is ~1/R⁴? If so, what about the COULOMB law for electrostatic fields?
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.
This kinda changes the traditional development of Quantum Mechanics which presumes simple sinusoidal waves. This approach is still combined sinusoidal and would require a Fourier approach to describe the waves in the Schrödinger equation. For example, a disturbance could produce a square wave which can only be broken down by Fourier analysis. As Spock would say….”fascinating”…
The electric field is conserved (it sums, positive and negative cancel out.) however, magnetic fields are NOT CONSERVATIVE: positive and negative fields remain unaffected by each other) You assume they both are conservative, fundamentally rushing to an incorrect conclusion.
There is a fourth option for the expanding field (you accurately identify light as an impulse phenomenon; expanding fields of impulses carry periodic force locations of accelerating forces (wave patterns that can have variable effects of resonant consequences) Light passing through some media with no interactions and others with amplified interactions and subsequent distortions to the traveling wave-front (light can change color with combinations of other beams, resonant waves, not just other atomic particles).
I have two questions:
(i) Does your explanation fits with those trendy about how the magnetic field is an electric field from the viewpoint of the moving charge that rises from length contraction (relativity)?
(ii) It is possible to explain with this equations why when I shot a green laser pointer into a glass filled with olive oil, the laser traces a red path within the oil? (non-linear behaviour, I think is due absorption and keeping the Kramers-Kronig relation)
I literally have Griffiths '"Introduction to Electrodynamics" open on my desk with this video playing, trying to make sense of it all. (LW was on page 429, by the way)
Well, you're right in pointing out that it's no surprise that light travels at the speed of light, since... it's light. But that is really missing the whole point. What *is* surprising is that this speed exists as a "special speed" in nature. What's significant about that *speed* (nothing to do with light here) is that if I measure something fly by me at that speed, then you will also measure it flying by you at that same speed, *regardless* of how we are moving with respect to one another. I might see the thing fly by me at speed c, and then see you fly by me at 0.99*c in the same direction. Naive thinking would lead to us assuming you would see the thing flying along at 0.01*c. But that's not how it works - you *also* see it flying along at speed c. And *that* is surprising - it's highly counterintuitive.
The muddle of how we talk about this is just a semantic shortcoming in how we choose our words.
It turns out that if you want the laws of physics to be invariant for all observers regardless of them moving at constant speed with respect to one another, then a speed that behaves in this special way *must* exist. That reasoning does not tell us, however, the numerical value of that speed. We know that because we have looked around us at the universe and seen how things behave - we *measured* the speed, and it just happens to turn out to be c. That's an observational fact. Then light *must* travel at that speed because light has no mass. Anything that has no mass must travel at that speed (in a vacuum).
I agree with you, at least, that the standard presentation of EM theory isn't the simplest, cleanest presentation. It's much more clean to regard the electric and magnetic field as parts of a single unified entity - a "second rank tensor" field usually denoted as F.
Also, you said something in there about the conventional theory claiming that EM waves "self-create." I don't think you literally meant that the claim is that EM waves can "pop out of nothing," but it almost sounded like that. That's not so of course - the energy housed in the field has to originate at some point. The fact that the wave can then travel through empty space, after it already exists, is then a fine claim - it's really no different from a wave move back and forth on a guitar string or a water wave moving across the surface of a lake. EM waves aren't really "special" in the sense of being some "additional kind of thing" - they're no different from any other EM field. It's just that if you create some arbitrary field configuration, the only part of it that's able to move through space is the part that has perpendicular electric and magnetic fields; any portions of your original configuration that deviated from that pattern just won't propagate.
All in all, your video has a tone that seems to imply that the standard presentation of EM theory is "wrong," and that's not so. It's not the "best" presentation, but it's usually done that way to avoid having the student need to wade into the mathematics of tensors. If the student *can* get to the point where they can do a tensor based analysis, then he or she can have a much cleaner, more straightforward view of the whole business.
I believe you are wrong in your first paragraph by saying that something moving at the speed of light passing one person at one speed will pass another person traveling at another speed with the speed of light too.
A radar beam travels with the speed of light. If it hits a car moving away at 100km/h and is reflected it will come back and hit my gun at light speed but it did hit the car at c-100km/h and the reflection is there fore at a slightly lower frequency (red shifted). It there fore would not pass the car at light speed. It can not both travel at speed c and have a wave length/frequency difference.
@@leonhardtkristensen4093 No, it's not the speed of the reflected radar beam that changes as a result of the motion - it's the frequency that changes. If the object is moving toward the radar unit, the frequency will be slightly increased, and if it's moving away it will be decreased. This is why you sometimes here them talk about "Doppler radar."
But, if I'm at the radar transmitter, at a fixed location on Earth, I will measure the return radar reflection moving at c, relative to me, and if you are on an airplane flying toward me, you will also measure it traveling at c, relative to you.
That's really pretty much the entire point of special relativity.
@@KipIngramThat is exactly what I am saying. The speed of light (EME) is exactly the same regardless of the speed of the emitter or the reflector. In regards to the emitter then if moving the wave will be suppressed (higher frequency) in the direction of the movement.
In regards to the reflector then if moving towards the beam will reflect the first part of the sine wave a little further away than the last part and as such compress the wave and make the frequency a little higher.
No body to my knowledge has measured the one way speed of EME. I believe it to be possible with the help of tricks like giving the measuring results digitally or in words (time independent) and have the clocks synchronized by phase lock over a set distance. It is impossible to measure the speed of a passing light beam. The best you can do is to measure it's frequency (color).
The statement that c is the same for all observers mean in my opinion that it is constant in regards to everything so if we observe it different it is the frequency, time taken or distance that has changed and not the propagation speed. That is exactly the same for a sound wave. It's propagation speed is dependant only on the media it is traveling in and not the emitting or receiving device. If there is a aether then that is the media that decides the speed not any movement of any observer.
psst, when EM wave travels through vacuum, there is no charges there;
only changing in time E fields, and changing in time H fields !
This is well articulated---really enjoyed it!
The orientation of the moving charge determines the direction of the magnetic field. Charges that are aligned congruent with their direction of movement will create a magnetic field that rotates around the flow of the charge. The charge fields will cancel out opposite charge fields, but the magnetic fields will not, they only add, not cancel. Opposite magnetic fields combine to have both polarity properties, but Opposite electric fields combine to have one field of a reduced potential. Since these fields only are detected by particle interactions, it makes sense to define what characteristics distinguish these interactions. (Tesla seemed to think it was determining the resonance of an EM impulse ( not a sine wave). He did pass his impulse streams through walls unscathed to melt or explode metals on the other side. Party on Dude.
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?
The point is that electromagneic waves do interfer with each other depening on their frequency, unlike two beam of lights.
see timeset at 5.
Unless you are referring to the ultra, ultra-high energies of quantum electrodynamics (like energies of the early universe) they do not. Classical electromagnetism is a linear theory meaning that fields simply add and do not interact. However it is possible to have so-called non-linear effects inside MATERIALS where the "fields" in question are actually a combination of the true fundamental fields PLUS the electric response induced in the material itself. We talk in this case of taking the true microscopic picture of only fundamental E and B fields and the charges of the atoms in the materials and develop a "smoothed" or "averaged" out macroscopic description of new fields called D, P and H fields that "bundle" together the "true" E and B fields with the emergent fields of the material itself.
However, it is important to understand that this type of nonlinear behavior in a macroscopic approximation of materials is NOT an indication that electromagnetic fields interact or that Maxwell's equations are non-linear. If one instead "zoomed in" from this macroscopic description of D, P and H fields back to the microscopic description one would see that any non-linear behavior is really only in these emergent fields, not the fundamental ones.
I guess this video didn't do much for me because I already didn't agree with the misconceptions laid out. My physics professors must have done a good job. But If someonedid have these misconceptions, you did a pretty good job debunking them!
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.
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.
Fun fact copper don't rust. Cover Copper around steel create electric magnetic.. Power copper up.
At the very beginning of your video you state that, "Changing Magnetic Fields DON"T Cause Electric Fields". Within this Charge-centric formulation of Maxwell's Equations, what is the mechanism for the induced current in a wire loop when a permanent magnetic is in motion near the wire loop?
charges are not fundamental things, therefore exists NEGATIVE and POSITIVE charges, fields are fundamental things that create all charges
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.
also we ALL have always assumed that its just light in air floating in star wars but who is to say the tech isnt some kind of fiber optioc super conductor that is coiled up inside the handle and when you activate it, it can shoot out in strands forming the "blade" and all of that etc many ways to skin the cat
Is magnetism the result that occurs when multiple eclectic fields collide (meaning the fields move)?
Holy shit after years of trying to intuitively understand this concept the gif at 16:40 finally made it click for me. Wow. Great video.
Since we are talking about magnets could a different way to say this be changing the wave distorts the electric field like when u put one magnet up to a phone or cpu and it messes with the screen but the computer has magnetic properties already metal and electronics but the phone by itself can still work
👏thank👏you👏 ... That is the first "honest" explantation I've heard that explains why how electric and magnetic fields for into electromagnetic radiation. It seems like the more easily digestible concept of fields is easier to teach but it is confusing in the long run! Thank you
Does it really explain why and how tho?