I think we need a video of BC holding a fluorescent tube under HV lines to observe the effect :-)

What is ingrained in my mind from a young age was when an electrician told me it was like "pushing marbles through a hose full of marbles. Add a marble in one end and one has to pop out the other end".

Clive: "Say this an electrical distribution tower..." * draws two giant scowling penguins * Me: "...wait."

As a post office telephone apprentice I was taught two sets of knowledge in parallel. On day release at technical college I was taught electrical and electronic principles while in the workplace I was taught the PFM principle. As an intelligent individual with a pedantic nature and poor education I was fascinated with the formal electrical and electronic principles but soon realised that it’s a rabbit hole that gets deeper and more abstract the closer you look at it. In the workplace the PFM principal says this is Ohms law and this is Kershoffs law. Everything else that makes these things a fact is Pure Fucking Magic and trying to understand it will just confuse you. Over the years, I’ve realised that trying to understand the root of these things is indeed confusing to the operational level of keeping most tech going. And given that since those early years I’ve managed projects where real live quantum physics have been employed by the very clever people to deliver a working system to a customer, I’ve learned that nodding in the right place and occasional grunts keeps,things moving.

Early telegraph systems used a single open wire and earth return over significant distances and worked just fine. The problem occurred when these wires were laid underground or under the ocean. The additional capacitance of the cable, coupled with its resistance, caused the rise and fall times of the current to be unacceptably long. When the first transatlantic telegraph cable showed this effect the reaction of the chief engineer was to increase the applied voltage. Unfortunately the increased voltage was too much for the insulation which broke down, and it didn't even cure the problem. It was the invention of "loading", which deliberately increased the inductance of the cable which, somewhat counter-intuitively, solved the problem. I can't remember off the top of my head which scientist it was that came up with that, but it was employed on later transatlantic telegraph cables. The technique was also used on telephone circuits until quite recently. When digital transmission (PCM) replaced audio on some medium-distance circuits in the 1960s and 70s the loading coils were replaced by digital regenerators.

The best thing about the veritasium video is seeing all of these videos discussing the subject. I certainly have learned more from all the discussions happening in videos.

In the original Transatlantic cable, they didn't use sounders but instead used very sensitive galvanometers. It took on the order of ten seconds to transition from a dot to a space. The throughput rate was very slow. As the cable began to fail, they kept stepping up the voltage until the cable completely failed. They had to wait until after the American Civil war to run a new cable. Two ships carried the entire assembled length of cable (tested in harbor before the ships ever left) They then sailed to the half way point and began laying the cable in opposite directions until they reached both shores.

As far as I know the output end of the early long-distance cables was not a sounder but an optical galvanometer. This is a typical electrical meter with a coil in a magnetic field, but the coil is very delicately balanced and has a fragment of mirror mounted on it. A light beam reflects off the mirror and illuminates a scale. The light beam takes the place of the needle in a regular meter. The advantage is that as the light beam has no mass it can be made arbitrarily long to amplify any movement in the mirror.

A curious tidbit about the 'arrow' on diodes and transistors. It's representative of a point contact diode. The line across the end of the arrow represents the germanium crystal and the arrow represents the cat's whisker. It doesn't have anything to do with current flow. It's just a happy coincidence it matches conventional current. The same symbol was used for point contact transistors. The base is a germanium crystal and the two diagonal lines coming off it are the collector and emitter, where the emitter was the one with the arrow head. That's a PNP transistor, as all point contact transistors are, and the arrow was simply flipped for NPN transistors.

I've worked in the telecommunications industry and have seen some amazing faults related to several aspects you have mentioned. Most commonly on analogue lines galvanic damage due to rain water. But I've also seen a sympathetic signal resonance between a taxi cab radio dispatch and a telephone line to a bookmakers. That was fun.

Something I was told by a dead Imperial College physicist: "Optical is really a tiny part of the spectrum. It just happens to coincide with the tight band of radiation that matter (solid stuff) reflects". The fact we can see "light" is no accident.

The capacitance of microphone cable on the cheap stuff can be heard by picking up the cable in the middle and dropping it on the floor. An audible sound can be heard.

Veritasium also selectively left out variables and misrepresented the case... And it's nice to have your take on it!

4:45 What I've once read, was that Maxwell began doing calculations on some phenomenon, and then his calculations showed that that phenomenon actually propagated at a *very* particular speed, c, the same speed as light. So he concluded that the phenomenon, electrical fields or magnetic fields or something, was somehow a kind of light, or was similar to light. It's almost three decades since I read that in a popular science book, though, and I've never really been able to understand advanced physics because calculus is a mystery to me.

"an electric shock is a very special thing too" I would argue that the last electric shock that almost killed me was quite terrifying.

So thankful you addressed this. In a way you describe his thought better than he did (for my brain). I love when 'in theory' goes against 'in practice'.

Without 'repeaters' every so often to reform any pulse wave shape, the inductance and capacitance of the cable will 'reshape' the square wave of a morse code signal into something similar to a sine wave. The overall metal jacket will look like a shorted turn to the signal further degrade the signal. I shook my head when I read 'Vs' description but there were already too many comments. Thank you for challenging his missive.

At 5:45 "The formulas being applied to justify saying the current flows on the outside; I get the feeling that they largely apply to the radio part of the spectrum". No Clive. The claim is that the _energy_ is flowing outside of the wire. Nobody is saying that the current in the circuit you drew is flowing anywhere except inside the wire. But the wire connecting the battery positive to the bulb (call it the red wire) will be at battery voltage (say +1.5V) and the wire connecting the bulb to the battery negative (call it the black wire) will be at 0V. That means a voltage exists between all of the red wire and all of the black wire that gives rise to a static electric field that we call E between the wires which is the change in volts per metre from the red wire to the black wire. There is also a static magnetic field going around the wire which is associated with the steady current flowing through the wire. Someone called Poynting realised that when we have an electric field (in your diagram from the top wire to the bottom wire) that crosses perpendicular to a magnetic field (in your diagram going into or out of the paper) then you could calculate what is called the vector product ( *E x H* ) and it would be a vector with a magnitude equal to the energy flow and a direction perpendicular to both E and H (in your diagram, from left to right, i.e. battery to bulb). In other words, there is a way of looking at the static electric and magnetic fields that occur in a DC circuit like your diagram and deriving the power delivered from the battery to the bulb. It comes out to be exactly equal in size to the conventional volts times amps that we normally use. In that sense, we can say that the electrical energy flows via the static electric and magnetic fields that exist outside of wires that have current flowing through them, and calculate *E x H* . But we could also say that the energy flows with the current and calculate V times I. It's just two ways of looking at the same thing, and the result is necessarily the same. You'll note, therefore, that I've emphasised the static nature of the fields and the steady current. There's no electromagnetic radiation of any frequency involved, nor any waves, and certainly not "the radio part of the spectrum". That's for your circuit drawn around the 5 minute mark, and I though you might appreciate a clarification of what is actually going on in that simple circuit. Nevertheless, as soon as you get switches closing and both voltages and currents changing, you're in another ballgame. In that case, there are transient electromagnetic waves radiating through the air which can also carry energy (although not much in comparison to the energy associated with the current flow in the steady case). It was the ability of the original presenter to conflate these two different phenomena that has led to all the debate.

What made Veritasium's Video so frustrating is the lack of an explanation of his assumptions - and the implications of these. For example, his "light bulb" is a device which cannot exist - it is able to turn on for any infinitesimally small current, yet it does not get turned on by the leakage current of the air.

Veritasium clearly wanted to explain the physics of electromagnetism, in particular the Poynting vector and the concept of the electromagnetic field (which is a different thing to "electromagnetic fields" by the way), and in so doing tried to come up with a simple thought experiment that would show how counterintuitive the theory is for the average person. To make it work, he assumes the wires are superconducting, that the switch and battery are ideal and that the lamp will come on with any current above zero, even infinitesimally small. He also assumes the usual things about the experiment being completely isolated from interference from the rest of the world. The problem is that he leaves the viewer with the impression that energy flows from the battery to the lamp *primarily* through the 1m gap, rather than "along" the wires. To justify this he does a bait and switch. He shows a small electrical circuit with a lamp and a switch in which the Poynting vector is somewhat correctly drawn traveling more or less across from the battery to the lamp (in fact a vector has a magnitude and direction, it is not a continuous curve from one location to another). He then switches back to his lightsecond setup and implies that the Poynting vector points directly across from his battery to the lamp in that setup too and so implies that most of the energy is transmitted from the battery directly across to the lamp at the speed of light. There are many problems here. Firstly, in his setup, the potential difference initially exists across the switch, assuming his lightsecond long cables took more than a couple of seconds for him to set up. This means that the disturbance which causes current to flow, and resulting electromagnetic fields, propagates from the switch, not the battery. Second, in his setup, the Poynting vector is zero at the surface of the wires because they are superconductors (in electrostatics, for wires with nonzero resistance the Poynting vector usually points into the wires in DC conditions due to ohmic heating, i.e. the energy is flowing *into* the wires to heat them; but that is not the case in Derek's superconducting setup). But external to superconducting wires the Poynting vector is *along* the wires, parallel to them, but with rapidly decreasing magnitude as you move further from the wires. In other words *MOST* of the energy flux is along and very close to the wires, in the electromagnetic field, which much more easily aligns with intuition than Derek's extremely misleading video. Thirdly, Derek very strongly hinted that his claim could be experimentally verified, which is bollucks. Even if he just uses lines of a kilometer instead of a light second, he won't find a lamp that will turn on with infinitesimal current. He won't find a kilometer of cheap superconducting wire either. The reality is the globe will light after about 1s as the bulk of the energy is concentrated very close to the wires. However, having said all that, there is a transient that propagates from the switch along the wires that induces a tiny (negligible) current in the wire 1m away due to coupling through the electromagnetic field. If the light could turn on with infinitesimal current it would light after just a few nanoseconds. In this specific time there is a very small amount of energy *radiated* from one side to the lamp on the other side at the speed of light. It's not steady state and will fluctuate due to capacitive and inductive effects and signal bouncing around and so on. But technically it is there. It just has nothing whatsoever to do with how the potential energy in the vicinity of superconducting wires is distributed in the large. The fundamental point that individual electrons do not have to move all the way around the circuit to the lamp for it to light is however correct. The *average* speed of the electrons is in fact very slow, orders of magnitude slower than propagation of energy in the electromagnetic field. The energy is in fact transmitted through the electromagnetic field in the direction of the Poynting vector, but for all intents and purposes this happens to be parallel to the wires mostly just outside the wires in the steady state. The whole thing is complicated by the fact that as phrased, the problem is an electrodynamics problem and not an electrostatics problem. Thus many of the usual equations people want to apply simply aren't valid until the system reaches steady state. It's also complicated by causality. For example you can't think of the wires as a giant capacitor because in 3ns only 1m of the wire either side of the switch is even relevant to consider due to causality (finite speed of light). By the way, there are some fascinating experiments that have been done to measure the electromagnetic field just outside an ordinary resistive wire using tiny seeds. In the vicinity of the wires the Poynting vector really doesn't point away from the battery towards the lamp when a DC current flows, but mostly along and slightly towards the wires. However, at the lamp, due to the fact that it is a resistive element, the Poynting vector points mostly towards the lamp. Energy comes out of the region surrounding the lamp because a potential is established there due to the wires carrying it there. This potential establishes a current (flow of electrons) in the lamp, and the potential energy in the vicinity of the lamp due to the potential established by the wires is converted to light and heat in the lamp. In the DC case *zero* energy is radiated from the battery, and I really mean zero, not approximately zero. Instead, the Poynting vector at the lamp shows the energy flux from potential energy in the region about the lamp into the lamp where it is converted to light and heat energy. I've tried pointing this out to the nerds who claim otherwise but years on they still insist they are right.

Sanity check: Run your wires through a faraday cage with a 3mm cable penetration. Heck, make it an S-bend. Does the bulb illuminate? Well maybe the situation here is more complicated than we had hoped. Edit: For a bonus put a smaller mumetal cage around the bulb to make sure the H field is also completely dealt with.... still illuminating? Damn.... electricity doesn't care about our Poynting Vector derivations.

I’ve been teaching atomic structure for longer than I’d like to admit. I liken our understanding of it to casting shadows. In the case of the electron, we can determine the mass of a single one very precisely, but we can’t know it’s exact location. We can count the number of electrons that move when a current is passed, but, as you point out, we have no way of knowing how that current actually moves through a conductor. It’s important to approach new theories with an open mind, but also to apply the logic we’ve learned to them. Keeping a civil and informed discussion going is worthwhile.

I'm so glad you made a video for this. I watched that video and it blew my mind. As someone who is still new and learning as much as I can, electricity and just what it is, is really hard to wrap my mind around. I understand the different theories, electron vs conventional, but it just doesnt make sense in my mind. Thinking of it in a different way such as fields or magnetism helps give a different perspective to help my puny ape brain. Thanks for all the videos Clive, you've helped me develop a healthy hobby that isnt slowly killing myself like before. Cheers buddy.

I've kind of been waiting for your input on Veritasium's video. I suffered the very problems you refer to, e.g. how would power transfer along a SWA, or screened cable, how do we only get a shock from the core of a conductor etc. And the comment about not burying cables due to losses - when cables are regularly buried! His video just didn't seem to tally with everyday experience. Glad you had something to contribute on the matter.

EEVBlog's video on it was quite good. Main bits I recall is that the light will turn on at C/1m time, but that near-instant effect will be from capacitive effects and be very dim for some amount of time. He also seemed to say the answer would be different with AC lines, but don't think he went into why that is. So from his viewpoint, the bits about high voltage lines are unrelated to the original question posed Very interesting points you bring up, and very much seems like Veritasium didn't limit the theories he talked about nearly as well as one should, leading to this "controversy" and so many of these follow up videos

I have used a Time Domain Refectometer for years and the thought that cable length and its distributed impendences are not important to electrical flow in a conductor, is, well idiotic and an insult to Charles-Augustin de Coulomb.

I think it's pretty amazing people invented all these different types of components when our understanding of how energy moves isn't so clear and potentially was wrong. Like when the diode was invented the inventor was using a model where electrons were moving from positive to negative.

5:20 Nitpickers’ corner: between Microwave and IR, there’s a range of frequencies up in the low-mid terahertz range that we hadn’t really figured out what to do with for the longest time. The last I’d read about it (about 8 years ago I’d say), the prevailing research was on using it for backscatter scanning, in airport security and possibly medical imaging applications. Hoping someone will chime in with any current knowledge on this.

Dave at EEVblog actually explained this one for me (odd cause I usually fall asleep before he gets to his point). I twigged that Veritasium he was talking about signals while ostensibly suggesting it was about power when he brought up transatlantic cables, but his answer violating the speed of light (and the unit/dimension problem) made no sense to me till Dave pointed out that he has his loop was 1m from side to side and that was part of the thought experiment and not just a constraint of trying to get a prop in frame. The original video was talking about free space signal propagation, and not about power delivery (the zero resistance wire is a red herring, but the infinitely fast turning on bulb with any potential at all was very well glossed over). Frankly I would watch a video about radio any day of the week, selling it as being about power delivery is just fraudulent.

Could I suggest a followup video -- your best understanding of how energy is _actually_ transferred along wires? 😸

I saw that he that Veritasium video, and remember thinking that he is increasingly looking for science to explain a hypothesis - instead of the other way around, as it should be. His explanation of his hypothesis was pretty simplistic, while your analysis of it introduced some complexities that were noticeably absent in his presentation. I like your take on the real world concept of this much more than I'm comfortable with his simplistic assertions.

Fascinating! Well played!

The undersea cable sounds like a problem Oliver Heaviside worked on and Kelvin's transmission line analysis. Heaviside's development of complex numbers and vector algebra was fundamental to the understanding the delay associated with capacitance and inductance in the cable. It (Telegrapher's equations) also was the precursor to the Shannon-Hartley theorem of bandwidth vs data rate.

Basically, Veritasium’s explanation is just a difference in semantics. He drew the fields outside the wire and said the power is in the fields, not the wire. But those fields are created by electrons moving in the wire, and so the wire is still necessary! It’s possible to transmit power wirelessly, but it’s inefficient at a distance. We do it all the time with radio.

Neat topic Clive! (And I learned something about those signal sensors too!)

Sir, your explanation is the best, very simple and clear among the other ponderings on this topic.

I remember that whilst attending meetings of the Rugby Amateur Transmitting Society (RATS) when it used to be held at Rugby Radio Station, now sadly demolished, when certain members used to use the trick to light up the carpark by merely placing a fluorescent tube in the gutter of their car, and keying the rig in CW mode.......Magic 😊 Regards, Keith (G4TDA)

The symbol for a diode comes from the old vacuum tube, where the electrons of the filament are being emitted towards the plate. The triangle is the cloud of electrons spreading out from the filament towards the plate.

One the best vids you have done! To expand on theatre lights, they usually use DMX as the data transmission type. DMX uses a differential signaling standard called RS485. The switching of polarity is great as when the two signals are combined at the dif amp receiver, in phase noise is cancelled out using common mode rejection. The same applies to balanced audio as well. Something so many in my AV industry take for granted. A fire and forget transmission type, so I wouldn't rely on this for mission critical events.

I really like how respectful you voiced your opinion as always. I tend to agree with it as well but both of yous explain things very well i like both channels very much.

Until I watched this it never occurred to me that the coils under the road at the traffic lights are actually like "humbucker pick-ups" on guitars

Hey, uhm i'm a layman with a little knowledge from back in my radio enthusiast days. I remember studying the effects of propagation, dampening and all the weird stuff concerning antennas. I specifically remember that thing called "Verkürzungsfaktor" aka nominal velocity of propagation. I mean pointing vectors (is that the correct spelling?) all neat and fine, but there was so much more to consider back then. I don't know if physics changed while i was looking away, but from what i remember is that you can have a potential differential anywhere you want within the limits of relativity at any time you want, but power transfer is a different can of worms. So yes, that lightbulb would see a different potential, but it would take time for the circuit to match to the demand that voltage would bring. Like you connect a bulb to mains and measure still 230V, connect the same bulb to a AAA battery and you measure my IQ ;-P Long babbling short it's a mismatch in internal resistance/impedance of the conductor/breakdown of voltage due to a quasi short circuit. All i wanted to say is that i thought the Veritasium video made too many omissions to to convey a fringe idea that does not include the change over time in a system. No delta t anywhere. And actuating a switch provoke some delta U, right?

I love how with this video, most of the electronics channels I watch have somehow mentioned or addressed this video at this point.

This is great post and I learned something new. Thank you.

I want to watch BigClive and ElectroBOOM eat a very large pizza together

Local ground potential differences can be a big problem on the rail network as we often have multiple independent electrical systems operating at both low voltage 650v AC (for signals) and high voltage 25kv AC for traction or 750v DC in areas with 240v residential power. It's not uncommon to see gates sparking where the hinge side is on the rail network earth and the latch post on the national grid earth. It's a bigger issue with access steps where the handrail may be grounded at one end and have a long run to where you step onto them.

Very interesting. Thanks for the video.

Discussing this stuff makes me happy 😊

I think VeritasIamNot did a very good job of making click bait, ensuring that lots of people would interact with his video and everyone would be talking about it, thus driving the algorithm higher, by being "accurate" but leaving out key details. For instance, most of what he talked about and made sound like it's stuff people don't know about, is actually well known in all Transmission Line Theory, which everyone from RF engineers to PCB designers have to take into account. And his entire example had nothing to do with the light year length of the wire, but rather the 1 meter spacing between the two sides via capacitive and inductive coupling, which happens right next to the battery and light, and doesn't go to the end of the wire. In other words, the results would be entirely different if it was a loop rather than balanced transmission line on spacers. Also, what he said about the nearly instant current flow would not have been enough to illuminate an incandescent light bulb, that would have to wait for the current to flow along the entire length of the wire, but what he was talking about was something that could only be seen on an oscilloscope etc, and was just that initial low level coupled charging of the capacitor, and not really the current from the battery that could light a light bulb. So yes, he was pretty full of it, and knew it! Lol Eevblog had a pretty good look at it.

I certainly disagree with Veritasium. Take length matched PCB tracks for example. If Veritasium is correct, the data would flow directly from the transmitting device to the receiving device, and mess up the timing. However, that's not the case. He's being vague when he talks about the bulb being 'on'. I can accept that there would be a flicker due to a surge in current by the switch, but It wont reach a stable continuous 'on' state until the current reaches it.

This was an awesome video. I hope all these various KZfaq responses get to him at some point so that he can do a video to address all the points that people brought up. He's certainly not completely wrong but there's nuance here I think that he would appreciate.

Been waiting for your insight regarding electron flow vs conventional. Thanks Bruh

Nick over at The Science Asylum did a video on this about 3 years ago, without all of the distractions that Veritasium added: kzfaq.info/get/bejne/eZ2khK1ll9SrnqM.html . His video includes a nice time-line, beginning with Ben Franklin losing the coin-flip about which charge actually carries current in wires, jumps ahead to Joseph John Tomson's discovery (1897) of the electron (in cathode ray tubes) and back to John Henry Poynting's theory of energy flow (1884, so not exactly "new", and not dependent on electron theory at all, since the electron hadn't even been "discovered" yet). While this theory is counter-intuitive overkill for understanding (low frequency) power flow through wires, if it wasn't true in all cases, there would be no such thing as radio.

VT is correct in deducing that the Poynting vector aims directly from the battery to the lightbulb. The thing is: in his setup the battery side and the bulb side effectively work as coupled antennas so when he connects the battery there’s an instant disruption in the electric field and that is transmitted by the wire ‘antenna’ one meter across to the ‘antenna’ of the lightbulb, transmitting a ‘signal’. However quite some time shall pass before the full flow of current will arrive. And indeed the full current flow *must* ‘explore’ the full characteristics of the circuit: what if there’s a 1 mega-ohm resistor half a light second down the line? When would that come into play in VT’s scenario?

I have seen all video responses to veritasium and BC is the one that gives a simple and understable explanation.

Love this Clive, pls do more theoretical vids!

There's a museum in Porthcurno, Cornwall dedicated to the first transatlantic cable.

I think EEVBlogs had a good take, In short there is the school of Physicists and the school of Engineers. Physicists usually have a grasp on how it really works, Engineers have a better grasp on how to apply it in the real world. I think we, watching your videos, are mostly of the engineering school of thought, but Veritasium is from the physics school of thought.

Great subject !

On the original video it's really a bit of a trick question. He sets up the problem like we are assuming a basic DC condition but the "gotcha" is that he has then applied AC theory. As soon as capacitance and inductance is brought into the equation then what he says is technically correct but in a really round the back sort of way. Conventional Current for me thanks.

The real way to draw a pair of wires is as a series of resistors on each wire, then between the resistors you have capacitors between the pair, if you have an outer screen, you can then draw capacitors from each wire to the screen Effectively you end up with series resistors and parallel capacitors along the length. a bit like a pi filter. Yep, there's all sorts of problems with multiple substations, where i worked we had 5 substations on the main site, one of the cameras on the CCTV system wouldn't sync because it was on a different substation, the cure was to install an isolation transformer in the video line. Screened cables should only be grounded at one end (the originating end) We had data between several buildings, the cable had a sceen and armour, when it was installed we had problems everytime there was a thunderstorm. they had grounded the screen to every cabinet, and not used the armour We corrected it by grounding the armour at every cabinet, ground the screen at main control, then looped the screen through each cabinet conneecting to the next screen, but insulated from the cabinet And as belt and braces, installed crowbar circuits on each cabinet's data lines

I also love Crystal set Radios probably could do with better Earth as I tend to use radiator pipe. When I was younger I made a capacitor/ Leyden Jar out of large plastic cup for Dice and foil and taped thin aerial in middle and charged it up with static on screen of my CRT Television in my bedroom enough that could feel charge in Air / ozone enough to make my Cat wake up and leave my room, and I got scared was too much so I touched it against the Radiator in my Bedroom and there was a spark and at same time a bang downstairs as it blew the water pipe under the kitchen sink clean off the wall where metal pipe was connected to a plastic y shape pipe junction and flooded the kitchen as water was pouring out so fast, I was in my Bedroom at time so my parents thought it couldn’t possibly be anything to do with me, they still think that to this day.

There is a radio station I listen to that gets inference when I plug my laptop cord in, when I turn the rear window defrost on in my car, and when I use certain electrical device within a ten foot diameter of a radio. It happens on multiple radios multiple sources of inference that shouldn’t be emitting radio waves and occurs constantly. It is only that station, other stations from the same broadcaster are fine. Edit: It is FM 92.1 incase anyone was curious.

At our last house, we had to call BT 3 times to stop the crackling on the phone line (each time getting the dire warning that we would be charged an extortionate fee if they didn't find a fault). Local cables were changed, terminals, tightened, but It finally turned out to be galvanic action on terminals in a remote cabinet. Wasn't very impressed with the fault finding, but don't have that problem in our new home- now have full fibre installed. Just waiting for Veritasium to say that our internet signal is not actually coming through the fibre optic cable! PS. As told during my days in the CEGB, Overhead lines are strung from Transmission Towers, Pylons are for mooring Airships! (BTW, the original definition of a pylon was an Egyptian Arch)

As far as I know, the first transatlantic cable was just single wire. I believe most of telegraph connections by then were single wires with voltage applied against the literal ground. The communication did not exactly rely on closed circuits, rather on measuring changes in electric potential in the wire against local baseline. The point is, Veritasium was trying to convey the perspective of power being transferred via combination of electric and magnetic field through the space. It's not wrong, it's just a perspective we use to explain the world because it is often useful. But explanation what happens in his experiment or why the transatlantic cable was a failure does not need such perspective and can be fully and sufficiently explained just using usual terms like induction and capacitance (resistance was in his thought experiment ruled out, except perhaps the lightbulb). I'd even say that this power perspective is only useful for stable conditions and totally does not explain why there appears current through the lightbulb right after we turn the switch.

I think VT's biggest problem is not making the distinction between "a signal" and "a flow". A signal is seen at the light bulb almost instantly because of induction between the wires, and that signal itself induces a flow, in reverse to the flow that would eventually come when the actual electrical flow picks up. Better, when the flow _does_ catch up, a lot of it will have been interfered with by the reverse flow transmitting wirelessly as a signal between the wires through induction. The undersea cables are related because, as Clive was getting to, nature is _full_ of tiny magnetic and electrical fields and potentials, so trying to pass a stable one through all that will see signal interference from millions of chaotic sources, which don't do much individually but add up over hundreds or thousands of miles.

Your mind should never be so open that your brain falls out.

Another great informative a interesting video.

I’m here simply b/c of the phrase “naughty Mr. Veritasium”

SWR meters illustrate coupling well. Also, my old RF teacher made me understand how "energy" works. Think of every time you charge up that big electrolytic by connecting it to a DC supply. Now, make one plate a round disk and the other plate a rod sticking up through the middle of the disk. Still a capacitor, but now it's an antenna... That'll charge up just like the electrolytic, but now it chucks out a huge EM pulse while it's charging. Current through the air...

Yes!!! This has been in my mind since high school!!! This reminds me to the wave/particle light issue.

It is great to remind people occasionally that we don't know everything and most of what we "know" is actually theory! Great video Clive

Here in New Zealand there is a high voltage underground feeder that runs at 220kV and it has reactors at each end to deal with the capacitance of the system.It only goes about 20km, but the capacitive effects are large at that voltage

Thanks for that, Clive, I now understand the meaning of the word, tangent. 😂 Seriously though, it's amazing how well our models fit with electrical and electronic circuits. It's interesting to pull back the curtain from time to time.

Dave over on EEBlog is the best I've seen. The key to remember is that All electrical energy is transferred through EM fields. So for a pair of very long super-conductor wires transitioning from "off" to "on" there would be a "pressure-spike" in the EM fields radiating out at the speed of light(ish). This would go out in all directions with power moving preferentially through the wires. The EM field between the wires would be modelled as capacitive coupling between the wires with the amount of capacitance tending to infinity as the wires get longer. So the light "turns on" about 4ns after the switch is thrown because of capacitive coupling between the wire, but it'll take a lot longer to ramp up to full power.

4:50 - sunlight being part of the electomagnetic specturm = I think Veritasium covered it. A light was shone through a prism to split into visible colours and the temperature was recorded by each colour of light. A control thermometer was set just outside of the red wavelength light but it was found to be the warmest. Infrared was discovered.

My first reaction to veritasium's video was "if its the fields carrying the power, why do you need the cable?" His whole explanation with the chain and mentioning how our electrical system has breaks in it really rubbed me the wrong way. the electron drift in one wire induces the drift in an adjacent wire either through inductance or capacitance. In between these breaks, energy is transferred from one side to the other via electric and magnetic fields. But inside the wire it really is that electron drift carrying the energy. The whole reason an incandescent lightbulb glows to begin with is because the electrons drifting through the filament have a sort of electromagnetic "friction" with the stationary nuclei that produces heat, which in turn produces black body radiation. Placing a lightbulb in a strong electromagnetic field without allowing the electrons to drift would not illuminate the bulb.

I knew Derek had pulled a thunderfoot and was talking outside his own expertise with authority when not informed correctly when A) "The light turns on in 1/C seconds because poynting vector" when the lightbulb would have no current though it so the cross-product of its own vector would be nothing initially, so not absorbing any energy. The energy coming out of the battery would be charging the wires, and some being radiated into free-space as an RF burst/EM wave. B)The 2 light-second-long loop would be tested for continuity instantly, which is obviously naughty and not how physics works. (I.e. put a switch 1/2 light second out at the end of one arm, when you connect the battery, it needs to be determined if that switch is open or closed before DC current starts to flow, so its at least one second before that information (I.e. the edge of the voltage wave on the wire) comes back to you.

Thanks for taking a run at this. I have many issues with many of Vertasium videos including this one. He starts talking about energy ie electrical work then conflates this with how electrons move in wires ie electrical force. Huh? Always enjoy your videos @

Great video, It is great to remind people occasionally that we don't know everything and most of what we "know" is actually theory! :)

Watch IBM's 'A boy and his Atom', to see actual pictures of atoms (fascinating). Veritasium's thing only works because of the changing fields at the moment you activate the switch (turn on transient), so it does end up as an AC /RF problem in a way, a transient contains multiple frequencies (listen to an AM radio while turning on a light).

I have no problem with exploring different theories. Sometimes a new theory opens the door to new approaches and new technology.

Ive been trying to learn about electricity recently and his video really confused me thank u for making this one

Wow, your taking me back. I was in automotive school and passed back in 1988 and we were taught conventional theory and the electron theory. Damn I'm getting old.

Electricity and magnetic fields are interconnected that why they can be explained by an electromagnetic wave. The theory exposed by Veritasiom does not negate the one you exposed. That theory is a further explanation of the how. In the model that you initially explained where electrons are pushed towards one end of the wire. For that to happen you need to transmit that push from one end to the other so it is like electrons pushing electrons pushing electrons. That can be visualized as a wave exactly as a wave on water pushes molecules in one direction. So you come to the conclusion that the flow of electricity is a wave. Furthermore, you are certainly aware of the connection between electricity and magnetic fields as you certainly know that electricity going through a wire always cause a magnetic field (that is the principle of electric motors). A variation of a magnetic field can also cause induced electricity in a wire (that is the principle of an electric generator). So a "wave" of the electricity will cause a "wave" of magnetic fields and vice versa. Therefore, you come to the conclusion that electricity is an electromagnetic wave.

Having cables under ground is a reall issue. They have to be calibrates with capacitors to remove the inductive load of the ground. This take a signifcant amput of power even for short runs. This is the main reason power cables is over ground. For DC cables this is not issue. So dc cables can go under ground, but they have a other problem. Joining them. Under sea cable is made in one go. Ground cables have to be joined in field, limiting the voltage to 350kV. Now there is some part that is absolutly corect with veritasiums statment. The issue is that he uses a dc source. If it was a ax source and that amout of cable. It would basically just be a huge antenna. While the energy would reach the lamp in one meter distance, the voltage would only be a fraction.

Thank you!

Ve is really a genius when it comes to generate views and attrack views from other channels. Good content of course.

I think the main misconception is that energy is transferred across wires in the first place. Even with the conventional theory, that does not hold since power is voltage times current and there is no voltage across a single wire. In the battery example, you can't point to a specific place where the energy is flowing since the current is flowing through the wires but the voltage is across the wires. But that doesn't prevent us from designing circuits, we can simply calculate how hot the wires become using current and if the isolation will hold using voltage. The pointing vector theory is certainly not disproved with any of the examples, but rather that it is just not practically applicable in everyday electronic design. Veratassium was plain wrong by his application to the ocean cable and he is very annoying by intentionally leaving out the fact that conventional theory simply follows from the Maxwell equations.

0:40 Has anyone seen an electron? What does "see" mean? Optically? Well yes and no. No in the sense that electrons are too small to be individually resolvable optically. But yes in the sense that the reflections from objects that make them visible are essentially due to the interaction between the incident light and the electrons of the object. But beyond that answer, what we know about electrons comes from many types of experiments that indirectly reveal the nature of electrons (and atomic scale particles in general), some of which translate into commonplace devices where the electrons behave in a well-understood fashion, such as in vacuum tubes. And of those, the CRT is a particularly visual example.

I work in high frequency RF. Veritasium is completely wrong and we can prove it easily by measuring the electrical length of a RF cable while physically moving the far end. Take an impulse generator (can be as simple as a charged capacitor), oscilloscope, and good length of coax cable - doesn't need to be much, 15 ft would be enough for a 50 MHz scope. Connect one end of the cable to the oscilloscope plus signal source and short the other end (leaving it open also works, but shorted will be clearer on the scope). When a spike is injected into the cable, it will propagate down the cable at a little under the speed of light, hit the far end, then bounce back to the start. You will see two distinct peaks on the scope - one when the spike first enters the cable, and one when it gets back from the far end. Now, move the far end of the cable relative to the oscilloscope and see if the distance between the peaks moves. I will put my entire net worth on the result being No Significant Change. We have cable which is specified not in physical length but electrical length - wavelengths at a specified frequency - and this is one of the ways it is measured.

For the "electrons move opposite of conventional current", I have always though about it that since electrons are negatively charged, when they flow one way, the current moves the complete opposite way (aka, what the negative sign does for pretty much anything) Probably not theoretically sound, but it's how I committed it to memory.

I think the biggest problem for undersea and other long cables is that the cable posesses series inductance and capacitance between conductors and/or ground. This forms a low pass filter and the leading edges of the data pulses get slowed and the pulses can no longer be measured. Resistance isn't a real problem, just fit amplifiers or start with a higher voltage. Same reason that undersea power transmission is usually DC. Long cables are too lossy to AC.

I don't think that Veritasium's theory is wrong. The Poynting vector is a well established quantity in electrodynamics and there is broad consensus among physicists that the Poynting vector does indeed describe the energy flowing through / transported by electrodynamic fields. Therefore the theory, that the energy does actually flow through the fields around wires instead of the wires themselves is in agreement with dozens of electrodynamics textbooks and is a direct consequence of Maxwell's equations. Arguing against this theory would mean to argue against Maxwell's theory: Good luck with that! However I absolutely agree with you, that the examples mentioned by Veritasium were kind of weak and did not necessarily support his theory. As you have quite beautifully explained in your video, there are other, simpler explanations for all examples mentioned by Veritasium. Especially the fact, that there are underground power lines as well, seems to discredit his reasoning behind overground power lines. However, just because his examples were weak does not mean his theory is wrong. Again, his theory is based on well established and undisputed electrodynamics. It stands on such a solid theoretical fundament, that the lack of good examples is not enough to discredit this theory. At least in my opinion.

It did not take long to get to this ;-) After I saw the original video I was thinking ... An answer will follow soon ! Thanks !

Thank you big Clive. I appreciate your video. I think it's great that you've cleared this up a little bit. When I watched the video from veritasium, I immediately thought that the theory was not correct also. Otherwise, insulated cables would never transmit electricity. Thank you and I hope in the future, not electricians will leave the electricity to the electrician's! Or, perhaps they will get educated about electricity!

Your thoughts make a lot more sense to me than Ve's video. I know his whole thing is being smarter than everyone else (and maybe he is and he's right) but the issues you brought up makes a lot more sense, And comes from real world lived experience, not theory. If you asked me who I wanted to do a critical wiring job; a theorist or an experienced electrician, I'd go with real world experience every time.

I was hoping someone would talk about this in a more realistic way. 👍 Derek's main point was the time to light the bulb was shorter than one might expect with such long wires. True, but there have to be a lot of assumptions, like 0 resistance and a bulb that lights with any current, etc.

Thing is, Derek says "bulb lights as soon as **any** amount of energy reaches it". This is the trick. And now we have to separate things discussed in this video: - The initial pulse you get in DC via the capacitor analogy (the two wires being the capacitor) is super tiny, not barely enough to light the bulb if you don't apply Derek's "trick". After that pulse we have to wait to the "real" current of energy reach the bulb. - Second point - which has nothing really to do with the above, but is just an interesting quirk from the physics formula - is the Poynting vector, which simply shows that Energy flows into a wire (with resistance) (the "wire" can also be the bulb), from the electric field. There is not really a reason to mix those two things together in one video. The first point is basically a question about how a radio antenna or a capacitor works, the second one is some obscure (and in reality useless) fact that arises from the formula. His video is misleading and puts two topics together that don't need to be in one video. But the good thing is, it makes people think. Although they now think that (all) the energy just goes through the air which is totally wrong. Now the real question would be, at what point does the bulb starts taking the "full" amount of energy (to make it light in real life and not just with his "trick") from the field.

I believe that the reason cross country power cables are strung so high is to stop the extremely high voltages arcing to ground through items coming close enough to create a spark gap. There are numerous instances of wildfires being caused by hot transmission cables drooping close enough to the ground due to heat from the environment and current flow to start arcing to vegetation that has grown due to lack of maintenance around the line paths.