6 ms·

There's two bits of controversy: 1) Slander: He claims that the way EE is taught is a "lie" but leaves out the many ways that standard EE models agree with his

There's two bits of controversy: 1) Slander: He claims that the way EE is taught is a "lie" but leaves out the many ways that standard EE models agree with his result. 2) Clickbait / inadequate explanation: he leaves out many details in order to make his experiment seem far more mind-blowing that it really is.* Critique 1 can be countered by saying he is targeting a lay audience (say, they took 1 high school physics course). Critique 2 can be countered by saying he is targeting a slightly more advanced audience who would understand those details (say, 1 or 2 college courses). But no matter who you think he's talking to, at least one of these critiques holds. * In particular: a) He doesn't explain how "1/c" is derived from the 1m gap. b) He portrays the electrical field as totally detached from the layout of the wires. But if you rearrange his lightsecond-long wires to be a circle, the effect won't happen. c) He leaves out the fact that this experiment works even if you cut the ends of the wires, which would change many people's intuition (think of the wires more like antennas). d) His thought experiment is actually wrong: see Electroboom's video, but basically by Derek's own parameters the light would _always_ be turned on.

lamontcg 5y ago
The problem is that his video is a mish-mash of two different concepts that were taught perfectly well in my freshman physics course. One is that the electric field travels down a wire at the speed of light while the electrons do not. The other is induced currents by moving charges. I got the answer "wrong" by watching the video because I didn't consider the tiny amount of current induced in the other wire to be sufficient to turn on the light in any useful manner. If you had replaced the light with a sensitive ammeter and asked me what the first point in time there would be any measurable deflection from zero, then I would have gotten it correct. Could have also just asked how this works, and the success rate would have gone way up (but he'd have lost all his clickbait): https://www.amazon.com/Fluke-324-Temperature-Capacitance-Measurements/dp/B009AZ0TXE https://www.amazon.com/Fluke-324-Temperature-Capacitance-Mea... Ask bad questions, get bad answers. Nothing wrong with how physics/EE is taught.
- phendrenad2 5y ago
  This is exactly it. If being "right" or "wrong" about something involves subjective facts (is the lamp "lit" by the small amount of electricity induced by cosmic rays too?!?!) and trying to visually inspect an experiment you can't access in-person, then the only thing "wrong" is the video maker.
  - ReactiveJelly 5y ago
    "Communicating badly and then acting smug when you're misunderstood" https://xkcd.com/169/ https://xkcd.com/169/
    - BrazzVuvuzela 5y ago
      Let's not forget that Derek's PhD thesis was about the practice of making videos that dunk on unsuspecting members of the general public.
      - thunderbong 5y ago
        I don't think there is any need to be snarky here. Link to his PhD thesis (PDF) - https://www.sydney.edu.au/science/physics/pdfs/research/super/PhD(Muller).pdf https://www.sydney.edu.au/science/physics/pdfs/research/supe...
        BrazzVuvuzela 5y ago
        I'm not being snarky, the formula of his videos at the time was 1) Ask somebody in a public park a science question. 2) They get it wrong. 3) Explain why they're wrong. His thesis was about the supposed efficacy of this style of video (which he has since moved on from, to his credit.)
        alisonkisk 5y ago
        You should look at the thesis before embarassing yourself further.
helsinkiandrew 5y ago
Much of electronic engineering is built around ‘lies’ - abstractions and simplifications because that makes sense in the vast majority of cases but are ‘wrong’ at some level. You don’t need to use Maxwells equations or the underlying semiconductor physics equations when biasing a transistor, or calculating the output of a digital XOR gate because there are abstractions that are far simpler to use and work in just about all practical situations. And of course those abstractions break down in thought experiments and beyond their limits in the same way that Newtons laws work up to a point and then you need Einstein.
j4yav 5y ago
Is this the same channel that made that credulous self-driving car video ad for money and passed it off as an educational video? Seems so: https://news.ycombinator.com/item?id=28949327 https://news.ycombinator.com/item?id=28949327
charcircuit 5y ago
Why wouldn't the effect happen with a circle? Shouldn't the same thing happen just with more delay since they are more separated?
- wtallis 5y ago
  In the case of a circle, you should still have a radiated signal that arrives before the conducted signal. But it would be far weaker, further compounding the problems with the "light bulb illuminating" way of illustrating that a signal has arrived. In the original experimental design, it was already reckless at best to leave the viewer with the impression that the radiated signal was capable of powering the light bulb rather than merely serving as a trigger for a self-powered light. With a circular setup, I doubt that equipment sensitive enough to detect the arriving radiated signal (and reliably distinguish it from other electromagnetic noise) could even fit into the light bulb's black box.
  - jonsen 5y ago
    The increased distance between the two points of measurement to be compared would also complicate matters.
dkbrk 5y ago
> He claims that the way EE is taught is a "lie" The thing is: this is sort of true. Now, all electrical engineers are very familiar with transmission line theory, that's pretty much their bread and butter. And all EEs know that if you're not working with well-defined transmission lines (like coaxial cables), you need to use a field solver. 2D field solvers are often sufficient, but if not 3D field solvers can and will be used. And then most of those same EEs, despite having just used a field solver which clearly shows that all the power is in the fields, which are in the dielectric space between the conductors, persist in using the mental model that electrical power moves in wires. This isn't just a pedantic quibble. There are real, practical effects. If you're designing a PCB and you have two signal lines with overlapping fields, those signals are going to couple, which will create common mode current, which will cause an EMI problem. You can stop those signals coupling by making them reference different ground planes, which makes the fields no longer overlap. If you route a signal line from one side of a ground plane to the other, you have to provide a path for the fields to get to the other side of the ground plane (i.e. "route" the dielectric, generally with a ground via), because if you don't, they will find their own path anyway and you won't like the results. If you persist in thinking that electrical power flows through wires, these sorts of effects are mysterious and only explicable through the magical black box that is a field solver. If, on the other hand, your mental model is that electrical power is in the fields, then -- surprise! -- the results of a field solver won't be so mysterious any more. And if you have a more accurate mental model, if you can predict more or less how the fields will behave before looking at the results of the field solver, then that means you can design with the fields in mind, rather than just tweaking things until the field solver stops being angry at you, but not actually understanding why the design works in the end. Don't believe me? Here's Rick Hartley, an extraordinarily experienced PCB designer: https://www.youtube.com/watch?v=QG0Apol-oj0&t=1102s https://www.youtube.com/watch?v=QG0Apol-oj0&t=1102s I found the responses from other EEs on youtube like Electroboom and EEVBlog disappointing. You can quibble about details of how he presented it (like, saying 1/c rather than 1m/c), but Maxwell's equations are the correct description of how electricity works, and Veritasium is absolutely correct in his core point which is that power flows outside the wires. Other models, such as lumped-element and transmission lines can suffice for many purposes but are ultimately wrong. Rather than responding towards him with hostility, perhaps they should have considered if their own mental models weren't quite as accurate as they had thought. As a final note, the problem as presented by Veritasium can't be accurately modeled by anything less than Maxwell's equations (i.e. a field solver), but you can get most of the way with transmission line theory and tweaking it with some physical common sense. Closing the switch causes electric and magnetic fields to propagate across the gap between the switch and the light bulb, and down the two transmission lines, at the speed of light (modified by the relative permittivity). The current that will initially flow across the light bulb, once the fields reach it, can be calculated from the characteristic impedance of two parallel wires acting as a transmission line. When the signals reach the end of the transmission lines, they will "see" a short and reflect with opposite voltage; when that opposite-voltage signal reaches the switch and light bulb the transmission lines act like a short and from that point on the light-bulb receives the full current. That 1m/c delay, in particular, isn't accounted for by transmission line theory at all. The way you get that (without a field solver) is by knowing that electrical power is in the fields, which propagate at the speed of light. Since transmission line theory can't accurately model the problem in full, I think Veritasium can be forgiven for not mentioning it (especially since he was targeting a general audience).

lamontcg 5y ago

The problem is that his video is a mish-mash of two different concepts that were taught perfectly well in my freshman physics course. One is that the electric field travels down a wire at the speed of light while the electrons do not. The other is induced currents by moving charges. I got the answer "wrong" by watching the video because I didn't consider the tiny amount of current induced in the other wire to be sufficient to turn on the light in any useful manner. If you had replaced the light with a sensitive ammeter and asked me what the first point in time there would be any measurable deflection from zero, then I would have gotten it correct. Could have also just asked how this works, and the success rate would have gone way up (but he'd have lost all his clickbait): https://www.amazon.com/Fluke-324-Temperature-Capacitance-Measurements/dp/B009AZ0TXE https://www.amazon.com/Fluke-324-Temperature-Capacitance-Mea... Ask bad questions, get bad answers. Nothing wrong with how physics/EE is taught.

phendrenad2 5y ago
This is exactly it. If being "right" or "wrong" about something involves subjective facts (is the lamp "lit" by the small amount of electricity induced by cosmic rays too?!?!) and trying to visually inspect an experiment you can't access in-person, then the only thing "wrong" is the video maker.
- ReactiveJelly 5y ago
  "Communicating badly and then acting smug when you're misunderstood" https://xkcd.com/169/ https://xkcd.com/169/
  - BrazzVuvuzela 5y ago
    Let's not forget that Derek's PhD thesis was about the practice of making videos that dunk on unsuspecting members of the general public.
    - thunderbong 5y ago
      I don't think there is any need to be snarky here. Link to his PhD thesis (PDF) - https://www.sydney.edu.au/science/physics/pdfs/research/super/PhD(Muller).pdf https://www.sydney.edu.au/science/physics/pdfs/research/supe...
      - BrazzVuvuzela 5y ago
        I'm not being snarky, the formula of his videos at the time was 1) Ask somebody in a public park a science question. 2) They get it wrong. 3) Explain why they're wrong. His thesis was about the supposed efficacy of this style of video (which he has since moved on from, to his credit.)
        alisonkisk 5y ago
        You should look at the thesis before embarassing yourself further.

helsinkiandrew 5y ago

Much of electronic engineering is built around ‘lies’ - abstractions and simplifications because that makes sense in the vast majority of cases but are ‘wrong’ at some level. You don’t need to use Maxwells equations or the underlying semiconductor physics equations when biasing a transistor, or calculating the output of a digital XOR gate because there are abstractions that are far simpler to use and work in just about all practical situations. And of course those abstractions break down in thought experiments and beyond their limits in the same way that Newtons laws work up to a point and then you need Einstein.

j4yav 5y ago

Is this the same channel that made that credulous self-driving car video ad for money and passed it off as an educational video? Seems so: https://news.ycombinator.com/item?id=28949327 https://news.ycombinator.com/item?id=28949327

charcircuit 5y ago

Why wouldn't the effect happen with a circle? Shouldn't the same thing happen just with more delay since they are more separated?

wtallis 5y ago
In the case of a circle, you should still have a radiated signal that arrives before the conducted signal. But it would be far weaker, further compounding the problems with the "light bulb illuminating" way of illustrating that a signal has arrived. In the original experimental design, it was already reckless at best to leave the viewer with the impression that the radiated signal was capable of powering the light bulb rather than merely serving as a trigger for a self-powered light. With a circular setup, I doubt that equipment sensitive enough to detect the arriving radiated signal (and reliably distinguish it from other electromagnetic noise) could even fit into the light bulb's black box.
- jonsen 5y ago
  The increased distance between the two points of measurement to be compared would also complicate matters.

dkbrk 5y ago

> He claims that the way EE is taught is a "lie" The thing is: this is sort of true. Now, all electrical engineers are very familiar with transmission line theory, that's pretty much their bread and butter. And all EEs know that if you're not working with well-defined transmission lines (like coaxial cables), you need to use a field solver. 2D field solvers are often sufficient, but if not 3D field solvers can and will be used. And then most of those same EEs, despite having just used a field solver which clearly shows that all the power is in the fields, which are in the dielectric space between the conductors, persist in using the mental model that electrical power moves in wires. This isn't just a pedantic quibble. There are real, practical effects. If you're designing a PCB and you have two signal lines with overlapping fields, those signals are going to couple, which will create common mode current, which will cause an EMI problem. You can stop those signals coupling by making them reference different ground planes, which makes the fields no longer overlap. If you route a signal line from one side of a ground plane to the other, you have to provide a path for the fields to get to the other side of the ground plane (i.e. "route" the dielectric, generally with a ground via), because if you don't, they will find their own path anyway and you won't like the results. If you persist in thinking that electrical power flows through wires, these sorts of effects are mysterious and only explicable through the magical black box that is a field solver. If, on the other hand, your mental model is that electrical power is in the fields, then -- surprise! -- the results of a field solver won't be so mysterious any more. And if you have a more accurate mental model, if you can predict more or less how the fields will behave before looking at the results of the field solver, then that means you can design with the fields in mind, rather than just tweaking things until the field solver stops being angry at you, but not actually understanding why the design works in the end. Don't believe me? Here's Rick Hartley, an extraordinarily experienced PCB designer: https://www.youtube.com/watch?v=QG0Apol-oj0&t=1102s https://www.youtube.com/watch?v=QG0Apol-oj0&t=1102s I found the responses from other EEs on youtube like Electroboom and EEVBlog disappointing. You can quibble about details of how he presented it (like, saying 1/c rather than 1m/c), but Maxwell's equations are the correct description of how electricity works, and Veritasium is absolutely correct in his core point which is that power flows outside the wires. Other models, such as lumped-element and transmission lines can suffice for many purposes but are ultimately wrong. Rather than responding towards him with hostility, perhaps they should have considered if their own mental models weren't quite as accurate as they had thought. As a final note, the problem as presented by Veritasium can't be accurately modeled by anything less than Maxwell's equations (i.e. a field solver), but you can get most of the way with transmission line theory and tweaking it with some physical common sense. Closing the switch causes electric and magnetic fields to propagate across the gap between the switch and the light bulb, and down the two transmission lines, at the speed of light (modified by the relative permittivity). The current that will initially flow across the light bulb, once the fields reach it, can be calculated from the characteristic impedance of two parallel wires acting as a transmission line. When the signals reach the end of the transmission lines, they will "see" a short and reflect with opposite voltage; when that opposite-voltage signal reaches the switch and light bulb the transmission lines act like a short and from that point on the light-bulb receives the full current. That 1m/c delay, in particular, isn't accounted for by transmission line theory at all. The way you get that (without a field solver) is by knowing that electrical power is in the fields, which propagate at the speed of light. Since transmission line theory can't accurately model the problem in full, I think Veritasium can be forgiven for not mentioning it (especially since he was targeting a general audience).