Deep Dive Historical Response to Veritasium’s DC Electricity Video

In this video I use the history of electricity to respectively disagree with Derek Muller's physics puzzle on what happens in a DC circuit.
Feynman's Lecture on the Poynting Vector:
Audio: www.feynmanlectures.caltech.e... S27 "Field Energy and Momentum"
Textbook: www.feynmanlectures.caltech.e...
"Joking" about Education: • You don't like it? Go ...
Videos Used In this Video:
Veritasium "Big Misconception" • The Big Misconception ...
Veritasium "How Electricity Works" • How Electricity Actual...
Veritasium and Electroboom • How Right IS Veritasiu...
Kathy Loves Physics "FM Radio" • Armstrong: the Tragic ...
Sir Lawrence Bragg on Faraday • Prelude To Power: 1931...
Discussion of TVs with EEVblog: • History of CRT Televis...
Kathy Loves Physics: "Maxwell's Equations" • Maxwell's Equations Ex...
LINKS for Kathy:
Website: bit.ly/GoKathyLovesPhysics
The Lightning Tamers book: amzn.to/3I7N4mq
KZbin Channel: bit.ly/HistoryofPhysics
Go Fund Me (for Audio book): bit.ly/DonateforAudiobook
Patreon: bit.ly/KathyLovesPhysicsPatreon

[@Kathy_Loves_Physics]

I thought this pinned comment could be a good place for people to add (respectfully) things in history and physics that you think I made mistakes on or need more clarification. Please nothing about sound quality or other superficials in this thread. Let me start: I wish I had added that when a battery is in a circuit the chemicals take a while to react, so that the electric potential difference from the charge distribution Delta V is less than the emf, or the chemical potential energy per charge. The equation becomes Delta V = emf - ir, where i is the current and "r" is the internal resistance. This is why a battery heats up when you have a lot of current flowing through it. 11

[@arctic_haze]

I sent you by email the PDF of a highly relevant paper on the very subject (Galilia and Goihbarg, 2005). You did not use it. Have you got it? BTW, I also think you misstated something about Feynman because you first agree with him and then seem you say that the same quote is nonsense. I've made a separate comment on that.

[@electrodacus]

I'm currently working on a video debunking his video about the direct downwind faster than wind cart powered only by wind. I was going to do do a video about the DC electricity video. To me this two are very similar and both have to do with understanding what energy is and the fact that energy storage is as important as friction in physics but much less disused. My simplification of Derk's DC setup will be using a charged capacitor instead of the DC battery and a discharge capacitor instead of the light bulb. I used this analogy and people have a hard time understanding why after the switch is closed assuming the two capacitors are identical just one fully charged and one fully discharged why only half of the energy will be in the two capacitors as half was lost as heat in the wire then radiated from the wire to the outside. And yes the switch is a capacitor and you can transfer energy to the light bulb by only moving the contacts closer to each other without closing the switch so mechanical energy used to move the switch contacts will get dissipated as heat including in the bulb filament but no energy has left the battery if you return the switch contacts to the original distance.

[@BlAcKpHrAcK]

The energy required to charge 30, 000 KMs of conductor, seems to be the limiting factor till quantified, the problem can continue being solved from there. Quantum is a synonym of the word magic, it only remains so till explained using correct nomenclature rather than ambiguous bucket-terms.

[@ShonMardani]

Why do you jump from one name to other, then continually admitting you did not understand, did not learn it and you disagree. Your only credentials is that you showed up in the class and looked at many science cartoons. Fineman put science on the map, what have you done?

[@BenignIndividual]

A worked example with known values would have been a good way to round off the video I think.

[@esra_erimez]

AlphaPhoenix actually tried to do Derek's experiment practically titled "I bought 1000 meters of wire to settle a physics debate"

[@peetiegonzalez1845]

Alpha's video proved, (in my view) that a transmission line is not the same thing as power supply. If the wires coming from the battery were perpendicular to the wires supplying the "bulb", you wouldn't even see much of a spike. And in any case you would not see continuous power.

[@zhoufang996]

Yes, his videos are very interesting, including the recent ones where he measured and visualised the "waves" of voltage propagating down the wire.

[@wolfumz]

​@@zhoufang996that video of Voltage waves is totally amazing and stunning. It truly makes the behavior of Voltage look like water. I'm a student in Electrical Engineering and I can't stop thinking about that freaking video.

[@personzorz]

And did an amazing job showing precisely how veritasium's argument is nonsensical

[@Ginto_O]

We know

[@philoso377]

Excellent comment, Kelly, you have pull this out of my lips - “real science makes you think and pseudo science makes you obey”.

[@Kathy_Loves_Physics]

Thank you

[@WJV9]

When I was studying Electrical Engineering in the early 1960's we first studied DC and Steady State AC circuits at lower frequencies. Then later we took a class in Transient Circuits and that introduced the concepts of electromagnetic waves and high speed transient effects of electrical conductors, spacing, conductor geometry, electric fields, magnetic fields and high frequency effects on circuits. Then we studied transmission lines, waves and antennas which then lead to Smith Charts and impedance matching and wave lengths, etc. I think what got Vertasium confused was conflating the 'transient' charge effects with the 'steady state' current/energy flow. Certainly an oscilloscope will see a 'pulse' of electric charge after the switch is closed but the light bulb required steady flow of electrons to create an (I^2 x R) energy flow to heat the filament and then create the light energy. Those two events don't happen at the same time. If all we wanted was to create an electromagnetic pulse then our house wiring could use hollow copper wires or 'wave guides' as microwave antennas us to move electromagnetic pulses around the house. However we need electrical energy to continuously flow to light bulbs and move motors, etc. so we must use 12 Gauge wire to move 20 amperes of current in a continuous manner to move energy without overheating the wire as the National Electric Code requires for all houses. The center of the wire as well as the outer part of wire all matter when you are transmitting DC or 60 Hz AC current flow to light bulbs, appliances, motors, etc. Of course if you are transmitting megahertz frequency signals to an antenna then the rules change but that is a different matter as I studied in college. Thanks Kathy for helping clear up the differences in electrical concepts of current flow.

[@calinbeale2634]

The only difference between AC and DC is whether the current flows through the valence electrons or the conduction band. While the conduction band is closer to the heart of the molecule it is not the "center of the conductor". It is not like the "flow of water in a pipe" that's a blatantly false analogy. Electron drift is from negative to positive. The flow of current is from positive to negative. In the opposite direction. The charge is a virtual photon that pops in and out of existence as the electrons oscillate up and down their respective bands of energy. Most importantly the charge flows in the "holes" left behind the electrons. Not through or in the electrons themselves. That's why plasma physics requires ion's with electron-hole pairs.

[@rodanone4895]

​@@calinbeale2634i think what everyone keeps getting at is "skin effect" which is frequency dependent depth of conduction. high frequency signaling results in charge density nearer the wire surface. the switch closure could be considered an impulse, which is all frequencies but the initial edge will likely be the high frequency portion exhibiting the skin effect followed by the quiescent dc state. when you look at the voltage signal on the wavefront it's a step function... high frequency initially followed by zero so the depth of interaction should be increasing with time. i would posit both components will raise the filament temperature. but the DC component will result in vastly more power dissipation, which makes the light.

[@pritambissonauth2181]

I think Derek's imaginary circuit should have had two switches, one on each side of the battery terminals and closes the 2 switches simultaneously to see when the light bulb lights up? Of course, oscilloscope probes place after each switch, may be Veritasium just published the videos for the views only!

[@gracenotes5379]

@@calinbeale2634 I was under the impression that valence electrons in a metal are already delocalized into a conduction band and that it is these delocalized electrons that are available to flow in a metal wire, either in a consistent direction under a DC electromotive force or in alternating directions under an AC electromotive force. At low frequencies, such as those used in utility grid transmission, I don't believe there is a distinction between the transport mechanisms for electrons through a metal conductor for AC relative to DC. At higher frequencies, we have to consider skin effect, but even then, I believe it is the same "sea" of delocalized electrons that makes conduction possible.

[@calinbeale2634]

@gracenotes5379 the one thing I would add is that it is not just the conduction band. The CB is a shell for electron orbital closer in to the molecule. The valance band is a lower energy electron band where the "free" electrons float in a cloud. The electron oscillates between these two shells. When it goes up a band it's because it accepted a virtual photon and gained energy. If it goes down a band than it gives off the photon losing energy. It is the passing of virtual photons that is the electromagnetic wave.

[@the.original.throwback]

This is the peer review process in action. Love it.

[@laurenpinschannels]

No, this wasn't equivalent to peer review, this was equivalent to response papers. Peer review works very badly compared to replications.

[@rjrmonkey]

​@@laurenpinschannelsobviously the veritasium video is already out there. I think this IS an actual example of peer review, in the same way that a response paper would be a form of peer review in the general sense of the phrase.

[@fotrj]

It is just an example of people creating controversy out of nothing.

[@julietbravo1695]

In order for there to be peer review, the reviewer must address the subject under discuusion, in this case the Poynting vector. All Kathy does is to profess a dislike for it and for David Jackson who includes a discussion in his book. Kathy claims to be a physicist, but seems unaware of the Poynting vector until the present discussion. I was introduced in my junior E&M course and saw it again in graduate school. The Poynting theorem is simply derived by dotting the E vector into Ampere"s Law and then rearranging to form a conservation law for electric energy. The Poynting vector certainly describes the flow of EM energy through empty space. What is needed here is a discssion of the Poynting vector in dc circuits. Kathy throws up a lot of irrelevant facts but never gets around to the real issue. She does make a glaring error by saying the the electric field is the (negative) gradient of the poential, which is only true in electrostatics. In electrodynamics, one must also have a vector potential to account for the unconservative nature of the electric field due to Faraday's law.

[@stefanjohansson1234]

I was one of those electrical engineers that reacted to Veritasium's video in a manner that can be best described as "wait a minute, that explains nothing". It's true that an electromagnetic wave needs no conductor, but DC current most certainly does. A lot of debunking of this has been going on since, and lots of good ones at that, so i won't go in to more detail here, but just saying that an explanation with the transmission-line model would have made perfect sense, and that the DC (battery) was a really bad example. I can see that you have been thinking both long and hard about this, and your result is excellent! What bugged me most about Veritasium's claim was the headline "electricity doesn't flow in the wire", well how else can you explain DC current? I'm really looking forward to more of your video's since i find that the historic connection is giving me a firm foothold of understanding, it makes me more grounded, so to speak. (pun intended) :-).

[@dggeers]

Energy doesn't flow in the wire...

[@elteck]

Another EE here. Yes I agree the transmission line model would clarify a lot, and it would explain that the light-bulb mostly likely will slowly ramp up in steps, as you see the reflected wave going back and forth between battery and light, that each have a different impedance than the characteristic impedance of the wire pair. If you look with a scope at the end of a not-terminated T-line you see exactly that. However, the pointing vector does work, even in electrostatics. I applied it myself when I wrote a field simulator (MOM based) to calculate the energy transfer. In this case you need to integrate the pointing vector over a closed surface surrounding the battery or the lightbulb. Voltage is only defined in electro-statics, and doesn’t work well if you have changing magnetic field. When we define voltage for an AC circuit, we use a quasi-static approximation.

[@kriswillems5661]

Nobody seems to realize that these wire pairs are in fact a networks of resistors and capacitors (transmission lines). Dave and Electroboom get it. But I think this video and Derek's video don't seem to understand it.

[@Hyxtryx]

@@kriswillems5661 I think Kathy said she had a graduate degree in electrical engineering. If so, she definitely knows what a transmission line is. BTW, you forgot inductor. 😛

[@tonib9261]

@@kriswillems5661Kathy mentions dc circuits, and steady states, but in my non-qualified opinion, the fundamental thing here that closing the switch on this battery / wire / lamp situation creates, for at least an instant, a non-steady state between the two steady states of off and on, and for that intermediate instant this arrangement behaves as an AC system, which is why transmission line theory explains what is going on. Overhead HV transmission lines have a capacitance to ground of several nF/KM, this experiment doesn’t need a light-second’s length of wires to illustrate, electricity leaking away in an AC distribution line is well understood.

[@reluginbuhl]

Part II about Feynman: I believe that he was speaking to religious zealots and other crackpots who are eternal science deniers. He was NOT claiming that you can't explain things to children. I do think you have misinterpreted his words.

[@tommihommi1]

in fact feynman was great at breaking things down and simplifying in order to explain them. He just was opposed to saying that the simplified way is how it works. When you simplify something in order to explain it, you should say that it's simplified.

[@nigelrhodes4330]

@@tommihommi1 I totally agree, that is the point of the Feynman diagrams and the "shut up and calculate" statement, he was always trying to show that the world is strange and wonderful and how things work as opposed to how we understand things work as they can often be mutually exclusive and that is what science is about teasing those two things apart to see what is real.

[@WayneErnst]

@Weirdly_wonderful I think I agree with the other commenters, here, about your take on Feynman's quotes which you said were about "education." I don't view the segment that you used about education or about speaking as "handed down from on high," the way you seem to be suggesting in your video. The clip you used was from the beginning of his 1979 University of Auckland lectures describing the theory of quantum electrodynamics (for which he and others shared the Nobel prize). When viewed in the rest of the context of that video (and especially that segment of his first lecture in the series), my interpretation of what Feynman was describing in that quoted section of video was "I am not going to make a fake analogy to give you some false impression about how this theory works, but because of how crazy the calculations look, or how strange the conception of the models may seem, you may not accept the conclusions we get to draw from this model and conception of how nature works. If you don't like that, you're either welcome to move to another universe where the rules are simpler, or try your hardest to come up with a different explanation and conception that fits what we've observed." In my view, this just expresses Feynman's personality and general commitment to not taking shortcuts in trying to give explanations for how things work (according to "the human beings who have struggled as hard as they can to understand it"). He says he can't make it simpler, because at that time (and as far as I know, even now) we don't have a simpler conception of how nature works, at that level (explaining quantum electrodynamics). But in my view, it is not a general remark he is making about explaining all of physics or a general remark about the nature of education. Would you agree with that?

[@rayhermans5555]

Totally agree. Wasn't it Feynman that said "if you can't explain it to a child, then you don't understand it yourself" (or something to that effect)? So no, I don't agree with Kathy in her view on Feynman.

[@rayhermans5555]

ps. Seems like it's a quote by Einstein... maybe I just remembered it spoken by Feynman...

[@punditgi]

Kathy is electrifying and totally awesome! No shock there. She illuminates this topic beautifully. ❤🎉😊

[@WarrenPostma]

Yeah this video is great. I wish I had science educators teaching me when I was in shool that were half as good as Kathy is at talking about this.

[@peterectasy2957]

@@WarrenPostma so if we have perfect circle od wire (length 300 000 km, diameter 95541 km ) and we push the switch, will that signal travel just one second ?

[@ultramurray]

Three sentences: Three puns. Three grΩns.

[@bobs12andahalf2]

She's a bright spark.

[@NERGYStudios]

This comment has a high potential to be punny.

[@stevewitman]

Love these videos!. Earlier today, AlphaPhoenix put out a video called "Watch electricity hit a fork in the road at half a billion frames per second" with some interesting observations and visualizations on DC electricity.

[@Kathy_Loves_Physics]

That sounds amazing

[@JustaReadingguy]

Funny, I saw alphaPhoenix' video just be for this one.

[@davidhomer78]

I just watched about half of the AlphaPhoenix video. He talks more about the flow of information than anything else. That is all pseudo science.

[@hareraiser5649]

​@@davidhomer78because he gives you all the information to follow the scientific method and repat his findings, it wouldn't be pseudo science.

[@danoberste8146]

@@Kathy_Loves_Physics It is wonderful. I get lost in the technical explanations, so I'm not sure Alpha Phoenix's video is directly or tangentially relevant to Derrick's video or not, but it seems so.

[@craigtevis1241]

Alpha Phoenix just posted a video where he measured voltage at multiple points along a wire. His animation of those voltages wonderfully shows the flow of electricity through a wire after a switch is closed.

[@glenncurry3041]

Incredible video!

[@philkarn1761]

Thank you, that was exactly the video I was thinking about when I posted my comment above about transmission lines. The theory is very well established.

[@anonymousinfinido2540]

​@@philkarn1761which video

[@webherring]

This video and Alpha Phoenix's helped me understand the topic. Derek OTOH seemed to try to "bewilder and amaze", for the view count.

[@MichaelPohoreski]

⁠@@webherringSadly Derek has become a shill capitalizing on sensationalism.

[@dggeers]

If you listen to Feynman he actually says that the theory (Poynting vector for energy flow radially into a DC carrying wire, etc.) is correct. He further says that our intuition does not match the theory but this is ok. Poynting (1884) shows that the energy (per unit time) flowing radially into the wire is actually the same as the power given by the much simpler, V*I. V*I is just much easier to calculate than the Poynting vector but it doesn't say anything about where the energy comes from (the E and B fields). All electromagnetic theory has to be expressed in terms of fields, the 'flow of electrons' is just a sideline. A full treatment would of course use Quantum Electrodynamics whuch brings us back to Feynman 😁 (Melrose's Quantum Plasmadynamics, may be a better jumping off point for someone interested enough to do the full calculation or at least draw the Feynman diagrams).

[@smokeybobca]

I've looked at almost all the comments. It seems Kathy doesn't want to respond to critiques that the Poynting vector is correct for DC circuits. She took Feynman out of context. Her rationales for not trusting the Poynting theorem are not strong enough and don't stand up to scrutiny.

[@luizcoelho5328]

Eric L Michelsen touched the right point. I suggest reading Oleg D. Jefimenko’s Electricity and Magnetism, topic 9-5. Displacement Field and Static Charge in Current-Carrying Conductors for clarifications about the static fields in conductors when steady current densities are present. Jackson’s 1996 paper indicates this when saying: “With the early notable exception of Jefimenko’s book, intermediate or advanced texts are no better”.

[@GianmarioScotti]

This is a very useful comment. Thank you.

[@luizcoelho5328]

Thanks for your interest, Gianmario.

[@adamsteed8573]

Love the actual experiments you’ve done! Great channel that I have frequently used before giving lectures to give some human interest to where these equations come from in the first place. Great book too!

[@billheffley2455]

Veritasium is often off the wall and somewhere out in left field for fake shock effects. People in YT just to grab a mega audience and make money doing so. You rock, Kathy. The truth wins.

[@karmageddon9136]

Another very good response to Veritasium's videos. One of Derek's reasons to make the original video was to spark discussion. I think you misinterpretted Richard Feyman's comment about keeping it simple. Einstein once said "God does not play dice" The response was "Eistein, you cannot tell God how to make the rules". One of Feynman's strengths was, "if at first you don't understand what you are looking at, then don't say physics doesn't make sense. Try looking at it differently till it does ".

[@ericlmichelsen2854]

I'm Eric L Michelsen, but Google is scrambling my name. To clarify, I'm affiliated with the University of California, San Diego (and my last name is spelled "...sen"). There is much interesting and useful material in this video. For example, I have given a talk describing simple experiments which show that power does NOT flow along the Poynting vector, and that is fully compatible with electromagnetic theory. For reference (but not claiming infallibility), I have a BSEE, and a PhD in physics, and decades of experience in laboratories and measurements; I teach this material at the upper-division college level. However, I think it is well established that the electric field inside a current carrying wire does, indeed, drive the current, and that this field is created by surface charges. Conductors can expel E-fields only in a static (or quasi-static) system. In contrast, a DC circuit is a steady-state dynamic equilibrium, and though the charges in the conductor move to reduce the E-field, the battery is constantly "pulling" them out of (and "pushing" them in) the wire, so they can never cancel the E-field completely. It takes only a tiny E-field in a good conductor to drive a significant current. This is established by extensive experiment, and organized into the detailed theory of electromagnetism (with no deference to anyone's authority). I have a detailed discussion of the speed of electricity and the Poynting vector in my "Funky Electromagnetic Concepts" (at the bottom of my web page), starting around page 69 (as of this writing). I performed (the moral equivalent of) Derek's experiment, and confirmed that in some very realistic situations (but not all situations), the bulb turns on nearly full brightness, nearly instantly (as expected from theory). My document includes photographs of my setup and results, and a discussion of the theory, but is written at the upper-division college-physics level. This is all well-established science, and fully consistent with relativity. (In Dr. Muller's follow-up video, I think he actually didn't give himself enough credit for his prediction.)

[@GianmarioScotti]

Could you please give us a link to your website?

[@wordpyramid]

google for: eric's physics web page

[@kantanlabs3859]

Well, I made some work about Poynting vector especially in quasi-static cases (in the circuit frame). According to me, there is nothing wrong with the present theories, only a poor understanding of the Poynting theorem I am afraid. The Poynting theorem doesn't say anything about the actual flow of electrical energy. Worse it gives infinite possibilities to define the energy flow through a vector field, all leading to the same balance. I have shown in one of my articles (published in the AFLB journal), that you may define an energy flow in a capacitor not going outside radially but axially (parallel to the wires) as your intuition suggest, with the same overall balance. More technically, you can add any rotational field to the Poynting vector without modifying the energy balance. Discussing where the energy flows from one point to another point is pointless :-) both in Maxwell frame and in the QED frame (In the quantum frame, the trajectory of a photon is not more defined). You may consider the flow of energy in the wire, or outside it like Derek and many others, or in circles as Feynman introduced in its course to illustrate the idea of the indetermination of the energy flow (you should have followed the entire course instead of extracting only a short portion of it !). If people generally use the cross product definition it is because it is clearer to describe waves propagation in vacuum, and also because its a relativistic invariant, but this is another problem we may discuss another day. The philosophical question about the actual path of electrical energy flow remains open I am afraid !

[@scottbrown4534]

I thought seriously. about creating lots of new accounts so I could like this video a bunch more times... Kathy, thank you so much, I still have tears on my face because of your kindness and humility, not to mention all of your hard work.

[@amarendrakumar5657]

Your videos are very informative. Please keep posting on regular basis.

[@idlikemoreprivacy9716]

Awesome channel. Perfect balance between accuracy, sources worth learning more from, and an engaging presentation. Chapeau!

[@thomassynths]

I think Feynman's quote to be one not about education but one about the scientific community. I like this take quite a lot. To me it's in the same vein as Tyson's "The universe is under no obligation to make sense to you"

[@fgoindarkg]

Tyson certainly has never made sense of it.

[@java4joem]

Agree. Feynman was very much in favor of education and explaining and there is much evidence for that view. Here he is pointing out that he's going to be brutally honest in giving an explanation and won't oversimplify it for the listener, which would be dishonest. He says the same when explaining quantum mechanics of light. I love your history lessons Kathy !

[@fotrj]

Feynman was an elite teacher. He wanted people to understand the concept, not just accept it because a bigshot scientist told them so.

[@ronald3836]

@@fotrj No, he wanted people to accept the concepts of modern physics even if those concepts go against our intuition. If some lay person tells him "time dilation is absurd, your math must be wrong, come back with something better", then he will tell that person to go somewhere else.

[@dougmarkham]

What Feynman was saying is that the universe has no need to be simple ---in terms of linear, intuitive to human understanding etc---and that one must accept experimental evidence over a neat simple concise but wrong theory. In terms of his views on education, there were two main sentiments expressed: 1) If you can express something in a way that ordinary people can understand,,then the likelihood is that you don't understand it as well as you think (that's his famous meme on learning) 2) Somethings in nature cannot be explained without first explaining a whole gamut of mathematics except by analogy. The second sentiment was expressed in an interview where the interviewer had asked him to explain how magnets work and why. Feynman could go only so far before he needed to upgrade the individuals maths skills. I think that your notion is entirely true in that: anyone should in theory be able to understand anything scientific; however, the depth of understanding does depend upon having or possessing mathematical ideas once you go beyond certain levels of knowledge.

[@gcewing]

The electric field inside a wire is only zero when there is no current in it. If it's carrying a current and it has resistance, there will be a charge gradient along it and therefore an electric field.

[@trygvetveit4747]

Great video!! Im interested if the cucit, but instead treated like a large circle and not two paralell conductors (EMP travel at light speed.) will this relate back to Cosinus to f ,and electrical motors?

[@der.Schtefan]

Have you seen AlphaPhoenix's recent video? Especially his second channel further explanations about impedence matching? I find it a great explanation as well.

[@domari9459]

Thank you very much for doing these well researched video topics with a lot of thought experiments that have been invested in them. Keep this going and take care of yourself. Cheers.

[@sankimalu]

I appreciate the time and effort you put into your videos, but my utmost appreciation is towards your tone. I love how measured and thoughtful your videos are. You make the topic very approachable for the newcomer, but also have enough detail and complexity for a well-rounded presentation. Your respectful response to his video is how such videos should be handled.

[@sirwinston2368]

I am a BSChE about ready to retire in 15 mos. Going back to my alma mater to get a degree in physics. Been watching MIT OCW (diff eq to refresh after 40 years) and Elliot and ViaScience... and you... and some others but your videos are fantastic. Thanks Kathy!!!

[@GavrielFleischer]

Love this! Finally a "fight" with reason. I'm waiting for Derek's response :)

[@EASTSIDERIDER707]

You’re reminding me of how I learned about ignition coils in high school auto shop. The transformer in an arc welder demonstrates these principles.

[@user-DongJ]

Great vlog & explanations! Do you have a video on memristors or Chua's circuit? If so, it would be awesome.

[@valentinaselektrikas]

Thank you for the fascinating video. Wondering if we change the switch with the transistor (I guess transistors do not emit emp pulses) will it affect outcome of Veritasium experiment?

[@bodynek]

I admire your videos. But now, i'm in love into them. You're great communicator and reinventor of old wonders and stories. Thank you for the great work. Looking forward to more videos

[@jamesmacdonald5556]

Does it make any difference if the battery with switch is already connected (open then closed) with the EMF being present throughout the circuit (even when switch is open) compared to a closed circuit with no switch, with no battery attached then simultaneously connecting both ends of the battery to the circuit? Would the speed of propagation be the same given all conductor lengths are the same?

[@kriswillems5661]

When you close the switch, positive charges start to spread on the plus pole, and negative charges start to spread on the negative pole. These charges cause on electric field. On the positive side, with the positive charges, the field pushes away positive charges in the parallel wire, on the negative side the field pushes negative charges away in the parallel wire. So an unbalance is created in the parallel wire and a current flows and the light goes on. This happens after 1/c seconds, because the field only need to travel 1 meter. It's pretty simple, both wire pairs act as capacitors. And DC pulse passes the capacitors (but a continuous DC voltage does not). The continuous flow of current happens only later when the electron flow in the wire starts. This happens much later. So, the bulb flashes after 1/c seconds, but it is only stable much later on.

[@T33K3SS3LCH3N]

I love these historical perspectives! Much of modern science communication is so difficult exactly because it is unaware of the original progression of discoveries that made us understand these processes in the first place. I think we should teach most topics by repeating the original discovery, with newer information only added in where they really make it easier to understand.

[@drbuckley1]

I have to go with science, which is why I assiduously follow your channel. You're a hero.

[@joeboxter3635]

Yeah - there is just one problem. Shinola gets 20Million views and a $100K check from youtube. Science gets 2000 views and lucky if it gets to million.

[@drbuckley1]

That's why I don't view the crank channels. Arvin Ash and Sabine are straight-shooters.@@joeboxter3635

[@randomdosing7535]

​@@joeboxter3635true

[@Zzzooooppp]

Bravo for summarizing the most important elements of disagreement before you even got to the table of contents.

[@hatpeach1]

Thanks; I was very confused by the Veritasium video which I was never able to digest. AlphaPhoenix just posted a series of videos that made much more sense in which he modeled charge as waves as it moves through wires. It struck me as logical and well presented, and so is a strong recommend.

[@ardeshiraminian9841]

I have a question. Is there any initial condition for the question that makes the veritasium answer correct? I mean what should the initial conditions for the switch and wires and light bulb be for the veritasium answer to be correct?

[@javiercastro8466]

Kathy, I bought your book and wow, so much good dope, kudos! I love history, and electronics has been a hobby of mine since 5th grade! I am self-taught in engineering, as I have no aptitude for a school environment, exams and drinking lectures as if from a fire hose.

[@joecliffordson]

Kathy. I just found your videos. I like learning from passionate women and I like your teaching style. Many thanks.

[@kennethsanders786]

...and I think I can reconcile two of my favorite science educators in my mind. Feynman frequently tried to be dramatic in order to engage his listeners and at heart is a theoretical physicist. Kathy is, at heart, a teacher, and to you, it is the teaching and communicating. Feynman wants the student to already have a complete grasp deep within maths. Kathy, is happy to explain in simpler terms. I like Feynman. I love Kathy. I have Feynman's lectures. I watch and re-watch Kathy's KZbin stuff to refresh my mind and reeducate myself for all the stuff I forget or forgot. Thank you, Kathy, for making me very happy. Thank you, Richard, for your contributions to science, too.

[@philkarn1761]

Exactly. They're really in violent agreement here.

[@ronald3836]

Feynman is happy to explain physics. He does that in his lectures. But he will (very obviously) refuse to bend physics just for the sake of people who reject concepts that contradict their intuition. That was his whole point. It had nothing to do with how to teach physics. Kathy misunderstands Feynman completely on this point.

[@philkarn1761]

@@ronald3836 Exactly.

[@MyhandleCH]

Can't believe we are equating a KZbin creator to Feynman. It's just laughable.

[@philkarn1761]

@@MyhandleCH That's unfair. Everybody has their contribution to make to education.

[@philhoward4466]

i have a huge 48 volt battery with a big switch connected (by a heavy short wire) on the "-" pole of the battery and 2 wires connected, one to the other side of the switch and the other wire connected to the "+" pole of the battery. these two wires run a great distance to i don't know where. i don't know what they are connected to on the other end. my question is this. when i close the switch, how much electric current flows over which wire to be interacted with whatever is on the other end? 3 amps? what if the 2 wires run all the way to the moon together? what if there is a light on the moon that the 2 wires are connected to rated for 48 volts and 144 watts?

[@EmblemParade]

The fact that people are STILL posting responses to that video gives me faith in humanity. I watch them all and every one teaches me something new, a slightly different perspective for thinking of how electricity works. Great one from Kathy here, with an illuminating historical perspective. For all the problems of that original video, hats off to Derek for pushing many of us to look beyond the elementary school depictions of electricity.

[@govtpeaches]

I really enjoyed this, and especially your insistence on positivity in the approach, it has given me a lot to think about.

[@RonnieBeck]

A fantastic video. Well presented and very informative. I love the level of detail and how everything is explained. Great stuff! Thank you!

[@galaxybounce82]

This is great that we are finally having a discussion about this. I think people think that electricity is like water and flows in the pipes.

[@Noosa21]

I love your videos, I used to have electronics as a teenage hobby and one of my uncles was working as a microwave electronics consultant in the 1970s here in Australia. I identify with all that you say. Lots of love from David Newton x

[@dougsmith3353]

Very interesting video. I'm curious if you have seen Nick Lucid's "Science Asylum" video from about 4 years ago titled "Circuit Energy Doesn't Flow the Way You Think" and what your thoughts might be about it.

[@user-yb9ol8sz7o]

With dc it's the electric field IN the wire that drive current and power IN wire and ac will be totally different. Sounds like you are correct. Great video. Thank you

[@tHe0nLyNeXuS]

I think this wholly comes down to semantics and what it means to "light up" the bulb. It also seems to have some relationship with the difference between the maximum speed of causality and the propagation speed of "meaningful" events in the physical world.

[@synonys]

So the bulb is not “on” even-though there is voltage and current after 1m/c seconds?

[@matthewf1979]

Thank you so much for making this. Real, useful power that will turn on and maintain a load takes time to do work. I agree with your conclusion.

[@monkwoo]

Hi, What is the reason of di-electric breakdown in high tension wires? Doesn’t that prove that energy does travel outside the wires??

[@davidlawson8103]

Cara professora de todos os canais de divulgação de ciências básicas em todo o mundo o seu é o melhor! Suas explicações são perfeitas! Você é a melhores profissionais da educação! Nas áreas de ciências exatas!👩‍🎓👏🏻👏🏽👏🏻👏🏽👏🏻

[@meofamily4]

I have your book, Kathy, and I admire it very much. You're doing good work.

[@jimjimx5418]

what is the mectromotive measurement of electromotive force

[@nigelrhodes4330]

I guess the bulb was powered by a capacitor with high Q with a stacked coil between would the bulb glow brighter than in a straight wire if the switch was pulsed? I imagine would be proportional to the Henries, Q and maybe the ESR as there would be an induced AC current?

[@peterpackiam]

Thanks & Cheers🥂,Kathy.

[@garyakirsch]

Thanks Kathy! The world is round again!

[@user-yb9ol8sz7o]

Yes I think you are correct Kathy. Poynting Theory does not distinguish between potential and kinetic energy so flow that seems unphysical will probably be potential energy. With dc there will be energy flow inside the wire.

[@roundgarage]

As a Master Electrician and keen viewer of your videos, can you please tell me if you think electrons go forward and backwards in an ac circuit. If so, how far backwards and forward do they travel. I've looked in my text books and spoken to my associates, but no one has a definite proof. Please help , thank you . John M French.

[@Zamicol]

Love, love, love this! Great job Kathy!

[@inappropriatejohnson]

Thank you once more, Kathy........just commenting to tweak the algorithm.

[@yogawithdennis4393]

Delighted Joy!! Keep em coming. Why wasn’t the resistance in the wire mentioned; perhaps because it is a constant (so long as the material in the wire is homogenous-:)?

[@supermikeb]

They were imagining the wire had zero resistance for this thought experiment.

[@racghineering]

how can our body being "charged"??? what if iam fly?in the end of the rod? can the alcohol light up? our body is watered(blood) how to lowering boiling point like the alcohol/ethanol/methanol?? will my body sweating?

[@robertsala6577]

Albert Einstein is said to have stated “If you cannot explain your theory to a seven year old, you do not understand it yourself”. I agree that anyone can understand any of the concepts in science if they are properly and concisely presented. I enjoy the presentations on this channel because they are presented so.

[@GianmarioScotti]

Maybe Einstein wasn't right about that. But your later statement is patently false - there are scientific concepts that are outside the reach of some humans. This is true also for me, there are things in science I know I csnnot fully grasp.

[@shabbirahammed4596]

what is the speed of electricity?

[@Tmanaz480]

As a lay person I've noticed that no matter the subject, a lack of historical perspective can be fatal to clear thinking. I think anyone who wants to study a science needs to retrace the path of those that went before us. Thanks for applying that principle to physics.

[@amfindo]

Kathy , I love your stuff, Ty so much😊

[@martinsechrist1393]

This is such a great channel. Thanks!!

[@stevengill1736]

Congratulations on your book! Cheers...

[@josephfredbill]

Actually, as you well know, Feynman did a a great deal to make physics understandable to people. Who is perfect across all areas at all times in their life.

[@WarrenPostma]

Right. I don't get the anti-Feynmann slant in this video here, it's quixotic and unexplained.

[@Kathy_Loves_Physics]

Honestly, I don’t understand your confusion. I don’t think it’s good for someone to put something that they think is obviously nuts and crazy in a textbook. Also, I do not know that he did “a great deal to make physics understandable to people”, as I’ve never seen a single example of that. I’m not asking for perfection, I’m asking for kindness. But I have not watched/ read everything that he did. Maybe he was kind and relatable in other areas. I just haven’t seen them. Also, we are allowed to have different opinions. I’m allowed to think negative thoughts about Feynman and still be a physicist right?

[@josephfredbill]

@@Kathy_Loves_Physics absence of evidence is not evidence of absence. Seeing involves looking. Maybe you have a responsibility to investigate properly, as you do for the characters you write about, before making such a public statement. Feynman did not have the attitude you claim, quite the reverse. Disappointed.

[@Kathy_Loves_Physics]

Warren, I am particularly interested in your use of the word quixotic. Quixotic is a reference to one of my favorite novels Don Quixote where a poor farmer decides that he is a knight, and a windmill is a dragon that he cannot defeat. But I don’t get what that means in reference to my video. I mean, you could be saying that I am not really a physicist, just as Don Quiote was not really a knight. But if that’s the case, then my complaints about Richard Feman are quixotic means that Richard Feinman wasn’t a physicist either, he’s just a windmill. Care to clarify?

[@tyscam]

It is hard to separate what Feynman did and what he claimed he did. The guy was an extremely good story teller and had a sizeable ego. That and he had a very poor attitude towards women. Kathy has every right to be suspicious of him, I can only imagine the amount of sexism she has put up with in this field.

[@AlejandroSilva-mr7yy]

All of your videos are a treasure

[@psyience3213]

I hate those "I'm an expert on everything channels" They're usually riddles with false information. I appreciate these kinds of videos

[@rsm3t]

The Poynting vector itself does not represent energy flow. If you integrate the P. v. around a closed surface, the result is the net energy entering or leaving (depending on sign) the enclosed volume. Alternatively, the divergence of the Poynting vector indicates if a locality is sourcing or sinking electromagnetic energy. Feynman was addressing the view that the vector itself represents energy flow.

[@ronald3836]

But note that Feynman does agree with the theory which is "obviously nuts". His point is that the theory goes against our intution, but that does not make it wrong (and if you don't like it, then I guess he'd say you can go somewhere else). Feynman also points out that the practical consequences are near zero, and I very much doubt that it has any real relevance to Derek's question. "Energy" is anyway mostly a bookkeeping device.

[@marcossidoruk8033]

​@@ronald3836There is this one experiment that you could theoretically do where you measure the gravitational field generated by the energy and energy flux distribution. However carrying such experiment in a lab is beyond current technological capabilities and as far as I know no one has postulated a way to do it with astronomical observations. This video was clearly convinced out of ignorance tho, she only ever appeals to intuition and doesn't provide any real argument against poyntings theorem being applicable in a physically meaningful way to DC circuits.

[@ronald3836]

@@marcossidoruk8033 That would be a very interesting experiment indeed. I guess "energy is just a bookkeeping device" might not sit so well with general relativity. But I do think it is correct to say that we can't help to think about physics in terms of abstractions which the universe itself does not necessarily care about. And of course that is why we do experiments to find out how far our abstractions can take us. There are these videos about "gravity is not a force", but that presumes that the Newtonian notion of "force" is more than a very helpful abstraction.

[@kerryjlynch1]

Thank you so much Kathy. Your channel is the best.

[@ronald3836]

You confused me when you first present Feynman as rejecting the Poynting vector theory, but then state that you reject Feynman's material on the Poynting vector. After checking the Feynman text in its proper context, I noticed that he gives further explanations why it "isn't so terribly puzzling" after all, with the right way of looking at it. Btw, in the "go somewhere else" video Feynman was NOT saying that some people may just be too dumb to learn physics. He is just criticizing people who have decided to reject stuff like quantum mechanics and relativity because it is "too crazy". Feynman's reply is that if you don't like this crazy stuff, go to a universe where the rules are simpler. And it mystifies me why you should even consider discounting the physics work of Feynman just because you (falsely) believe you disagree with him on a point of pedagogy. All in all, this video does not paint you in a very good light at all.

[@amunt3r]

I was very disappointed to see the video end with (E) as the answer i.e. it depends on specific properties of the components used. Could someone please suggest which of (A) to (D) is *closest* to the correct answer? (with idealized components or not, dealer's choice)

[@mrmadmaxalot]

I remember when his first video on this came out and there was a big reaction and discussion to it. I feel it was the perfect educator situation, since it forces someone to really start pondering how all of it works before they can even start to come to some conclusion of their own. In the end, the places where he was wrong seem mainly to be from oversimplifying for pedagogical reasons, and slips of wording that were wrong or make it debatable what was meant, all of which allow for misunderstanding (since I am sure Derek himself understands this, it is more a matter of presentation). It is great that even after all this time, people are still making responses to it, and getting people engaged with the details of how it all works.

[@psyoperator]

Oh... thats awesome!... you love history and physics! I would love to hear your breakdown of the 911 building collapses!

[@fluffycritter]

The timing on this video is perfect as Alpha Phoenix just released a video about a similar thing, but his explanation of what’s happening felt a bit lacking to me.

[@petevenuti7355]

Derek knew exactly what he was doing when he created this passionate debate, catering to the algorithm and justifying it for education.

[@MichaelPohoreski]

A shill selling sensationalism? I’m shocked! /s

[@JohnL2112]

Re Feynman, as a fellow New Yorker (but uh, not a fellow genius) I think he was just getting at there being a level of irreducible complexity where intuition cannot take you and you have to rely on the math, stated in kind of a sarcastic way. Its ok if you take issue with that, but I don’t think he was insulting children there, just that… like, if you want a 5 year old to understand the path integral formulation of quantum mechanics, the 5 year old will need to be a 6, 7, 8 , 10, 15, 20 year old that learns all the intervening math, and classical physics. Feynman is just saying he can’t do that work for you - thats my interpretation.

[@jimprice1959]

I agree with your comments re the scientific process. Also... If electrical energy flowed on the surface of a wire they why not save copper by using hollow conductors?

[@HWPcville]

I give you 2 thumbs up! I don't really understand all things electric but I do have a great fascination with them. When I watched Derick's video on how long it would take to light a bulb I felt uneasy with his explanation although I wouldn't have been able to verbalize it. Your video helped my understanding of my original unease. I also greatly appreciate your definition and comparison of true science vs psudeo-science. Thanks for posting.

[@noproblem4260]

if electricity doesn't flow in the wire, why you need big sections for high currents??

[@terryhollands2794]

You come across like a very nice and reasonable person. ❤

[@InXLsisDeo]

Worth noting that "the Jackson" is a well regarded textbook. That's one I've opened in my undergrad studies.

[@copernicofelinis]

Jackson is THE bible in classical ED. If someone says Jackson is wrong on something, they better be prepared to bring proof.

[@BarriosGroupie]

Yes, it's a masterpiece: written by someone deeply passionate about the subject.

[@richardfoster2895]

If it's an incandescent bulb it also takes time for the Tungsten filament to reach luminous temperature.

[@paulinnanjing]

If you're going to accuse Richard Feynman of not believing in science education and presenting things in an accessible way, then you have already lost. Absurd. Besides, how far out of context do you want to drag this quote of his?

[@DavidMFChapman]

If energy doesn’t flow on wires, why do they get hot?

[@cr-pol]

the veritasium video was about not being "in" .

[@markotrieste]

Well, you could argue that energy flows in the vacuum and the drift of electrons in the wire are just a consequence of the fields created by that energy flow. Wiring is just shaping that field, and the electron flow is a side effect.

[@Martinko_Pcik]

Thank you for this response to that video which bothered me for quite some time.

[@TheBartman47]

When I was in college, the professors acknowledged that the electrons flow from - to +, but to keep the math easier, we engineers cleverly came up with hole-flow theory... as an electron moves, it leave a gap, so the one behind that comes in to fill that spot, but it left a hole and the next one behind that moved to fill that gap, and so on. If you look at this gap, or "hole", it is moving from + to -, hence hole-flow theory.

[@michaeldepodesta001]

Beautiful: Thank you.

[@scottmarshall1414]

On his original video I asked what would happen if the wire had been in a circle of the same length instead of parallel lines connected at the far ends. No one answered

[@drfisheye]

As long as the bulp would be at one meter of the battery and switch, the results would be the same.

[@placebomessiah]

This video is awesome, i love the way you presented everything, and I love the nod to Mr Rogers. I share your philosophy about everything being explainable to children. What i would love even more is if you could help the (nerd) world understand how Barker codes work for radar and wireless systems

[@realcygnus]

Nifty as always !

[@joehopfield]

I avoided watching Derek's click-baity piece and the responses for all this time, waiting for your take. AlphaPhoenix's careful measurements are also very fun and clear emperical evidence. You rock.