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Comment by 0xTJ | Hacker News Reader

That Veritasium video is one of the most controversial educational videos I've seen. I think one of the issues with it is that it's a bit pedantic, but also ignores other issues, that invites other people to be pedantic about it.

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Controversial is fine to the extent the controversy shows people struggling toward clearer understanding and better explanations, and as long as all parties are operating in good faith (i.e. not being deliberately misleading).

Let me highly recommend Mehdi Sadaghdar’s (ElectroBOOM) excellent response video https://www.youtube.com/watch?v=iph500cPK28 which does a great job of empirically investigating and theoretically explaining the subtleties involved, in a polite, respectful, and entertaining way.

I have similarly enjoyed the exchange between Sadaghdar and Steve Mould about the physics of the “chain fountain”.

These kinds of friendly scientific “debates” show viewers (e.g. kids) a bit of how the scientific process and scientific discourse works, in a form that is more accessible and digestible than technical journal papers or history books.

Having a discussion back and forth helps to improve both viewers’ specific knowledge and viewers’ processes for comprehending and interrogating new information, so long as the median viewer actually sees some of the responses. (Someone who only ever saw the first Veritasium video probably ends up with a somewhat wrong mental model.)

Teaching. What a concept.

It warms my heart to see a generation of scientists, engineers and communicators attacking frontiers again.

For a while there it felt like just a few of my friends were fighting for the future and everyone else had written it off to Sci-Fi.

ElectroBOOM's exchange with a retired MIT professor (it was over whether or not KVL always holds) was also very polite, respectful, and entertaining and yet surprisingly the professor who must have received and exchanged feedback before having published many, many times seemed to have a meltdown over a the disagreement.

Successful professors can get to the point where they’re no longer interacting much with people who disagree with them.

As much as I love Veritasium, I feel the OP video is better than his. Actually doing the experiment is really good, and it honestly feels like he was fishing for another debate like the faster than wind car by giving only a super theoretical and unintuitive explanation. (I don't have any real evidence of that, but it does /feel/ like it.)

I also wonder what would happen if, instead of a setup like this:

  ┏───────light────────┓
  ┕──────battery───────┛

You did something like this:

  ┏──────────────light─┓
  ┃                    ┃
  ┃                    ┃
  ┃                    ┃
  ┃                    ┃
  ┃                    ┃
  ┃                    ┃
  ┃                    ┃
  ┃                    ┃
  ┃                    ┃
  ┕─battery────────────┛

That is, battery (and switch) and light at opposite corners of a large square, instead of on the middle of a long double-line. Veritasium video implies the current will start flowing at sqrt(2) * width, instead of at 2 * width. Would these effects really work over longer distances like this?

Yeah, this is what im wondering. The proposed mechanism for this is that the wires generate electric fields that influence electrons remotely. Fine.

What happens when they are not close enough for any meaningful electric field interaction?

He says near the end of the video that a Part 2 video is forthcoming with more exploration of:

- Different sized loops

- Wires closer together / farther apart

- Wires on the ground instead of in air

- Current on both sides of switch

- Wires in two big spread-out loops

- Different strength resistors

The "fast plateau" is pitiful from a power delivery perspective even under tight coupling. Under looser coupling, it becomes proportionately more pitiful.

If they're not connected, then they're just two antennas. What happens when you get far away from your wifi hotspot or a cellphone tower?

The voltage/energy transmitted becomes vanishingly small, and smaller than the thermal noise of the electrons in the other antenna, and undetectable. https://en.wikipedia.org/wiki/Johnson%E2%80%93Nyquist_noise

Presumably yes, but it would be very hard to measure since the field falls off with r^2.

I think the issue with the square would be that the capacitance would be much, much smaller since the wires are separated by a large distance (square law). The capacitance of the original setup is already quite small, but at least it's noticeable on a decent scope. But I doubt you'd see that effect in the square setup.

The other issue with the Veritasium "setup" was that he specified that the wires had no resistance. That being the case the RC time constant would be 0 and thus you wouldn't see that initial charging of the capacitance (and associated current flow) because it would happen instantaneously under those assumptions.

The current will always start following after the distance between the switch and bulb divided by the speed of light amount of seconds.

Hey, did you make that ascii art by hand or did you use a tool I don't know about? If it's a tool I'd like to use it :)

Just copy pasting from https://en.wikipedia.org/wiki/Box-drawing_character

Nice thank you. TIL

The further the battery and switch get away from the light, the less current you'll see at the battery at (sqrt(2)*width)/c s, since the electric and magnetic fields around the battery and wire will drop in strength as you move further away from them.

Put another way, the main reason this effect is observable in the way shown in the video is because the light and battery, and the wires between them, are so close together. Move them further away, and, per the inverse square law, you'll start seeing a much lower induced current-- the effect may still be there, but it won't be measurable over the noise floor of the experiment setup.

You're right, but sorta. Which is the big problem here, any simplified analogies break down.

What's happening is that you are straying further and further from the "impedance matched" condition (the inductance per unit length stays the same but the capacitance goes up with the separation--however, being "too close" will also cause similar behavior). Consequently, the energy transmitted per reflection gets smaller and smaller.

Part of the problem in this whole discussion is using a "light" as a "threshold detector" where the threshold is effectively microamps. A microamp threshold detector is not what people think of as a "lamp".

If the original Veritasium video had showed the current flow via meter, oscilloscope, etc. nobody would be terribly surprised as it would show small flows getting bigger upon each reflection until it built up to the full current.

This makes more sense and was my first thought watching the video.

Question: At which point does the influence reach actual zero? If it doesn't, does that mean the coffee in front of me is being influenced by Jupiter, however minuscule?

In field theory, IIRC, fields (absent special setups, i.e. in space) are never actual zero, but due to reverse square law they become too small to actually care about quite soon. But the quantum model may have some limitations on that, since stuff can't be arbitrarily small there AFAIK. Not sure what happens about the gravity - likely, Jupiter might influence your coffee, even though in an immeasurably small way, since gravity is very weak. We know the Moon influences our oceans quite prominently. But maybe there are minimums there too?

Once the light and battery are far apart, I have a horrible suspicion that the definition of simultaneity will become problematic.

As a parent, Veritasium would be way more preferred teacher to inspire students to search for answer. There are many stellar students who scored A* that later in life just dump what they learnt. You'll be surprised how many medical students didn't make it to MD or not a MD anymore a decade later. Having someone that spurs you to work for it is a weight in gold itself than a great tutor helping you score full understanding and get that A*.

You also need to account for the fact that oscilloscope wires would also be longer going to the light bulb. You can imagine this on the extreme case where light and battery are 1 km apart. Now, you need oscilloscope wires to go 1km far to connect to the light bulb and your timing is off.

> I think one of the issues with it is that it's a bit pedantic, but also ignores other issues, that invites other people to be pedantic about it.

I think the video is intentionally misleading. He got a taste of how "successful" a controversial video can be with the "Wind powered car going faster than the wind" thing, and he's leaning into that. I just don't see any other explanation for how he chose to frame the problem.

I completely agree. When I got an EE degree, most of the content was about how electric fields work. It's not a simple concept. That video was reductive to the point that it made me angry. For all practical purposes, he is wrong, and he should admit that.

Not everyone has an EE degree.. As far as I can tell, the majority of the video seemed like a honest way of explaining the electric field / "flow of electricity" phenomenon to the layperson.

That's unfortunate because his content used to be very good and this video seems only seeking engagement at a very shallow level, e.g. doesn't even mention transmission lines.

My early thought was that, at the very least, Poynting Vectors deserve a video but Transmission Lines also deserve a video.

Here's a problem I recall from Jackson which might (or might not) provide a missing link:

Given two parallel conductors of arbitrary shape, prove that the product of capacitance-per-unit-length and inductance-per-unit-length is a constant (i.e., independent of profile and separation).

I remember finding a suitable answer, but I can't for the life of me remember how.

Watch his vid again. Transmission line mentioned. He even use the issue with putting cable across the ocean having issue as a possible example explain his thought experiment. Could it be you used to watch his vids in full and remember and not so much for this one?

The term 'transmission line theory' (or even 'transmission' for that matter) doesn't appear to have been mentioned in the video at all[0], and this is a complaint that was also raised by Dave Jones[1] in his critique of sorts. The video is fundamentally about transmission line problems and the term is mentioned both in the description and the word document containing further analysis, but its omission does lend some credibility to the complaints in the parent comments that the video style is intentionally pedantic (it is a pure physics vs practical electrical engineering take after all) and presented as a controversy which comes off as a bit shallow as a result.

If one were to put on a tinfoil hat it doesn't seem like much of a stretch to imagine that the plan was to have a follow up video to settle the controversy with the gist of the video being about transmission line theory and concluding with a practical demonstration of the effect.

[0] I don't have the time to carefully watch a 15 minute video to verify this, and demonstrating a lack of evidence seems difficult, but the subtitles for the video can easily be downloaded with youtube-dl and then grepped or opened with a regular text editor. Note that these subtitles are manually written and not auto-generated by youtube, and while it's possible there's some differences in the script and what is said it seems unlikely.

youtube-dl --write-sub --sub-lang en --skip-download https://www.youtube.com/watch?v=bHIhgxav9LY

grep -i 'transmission' 'The Big Misconception About Electricity-bHIhgxav9LY.en.vtt'

[1] https://youtu.be/VQsoG45Y_00?t=1013 (16:53)

That video perfectly summarizes online discourse. I personally found it fantastic as a resource. It was the best and most clear explanation of transmission of energy in an electrical circuit that I have seen. It debunked a lot of myths in my head that we were all taught in school.

The thought experiment he proposed was just a hook to keep people interested - and it certainly did the job. Because it is a popular internet video by a popular YouTuber, however, the entire scientific community made it a mission to nitpick every detail of that experiment and show that the conclusion wasn't 100% accurate without a bunch of caveats. Which is fine, I guess, but also missing the point of the whole thing.

I'm sorry but no, the original video does clarify some important things that people misunderstand about transmission of electricity, but then it piles on a bunch of other really unclear information with no explanation. It answers a question with about 8 other questions and then offers no help in understanding any of them.

You can't just say "there's electricity at the light bulb nearly immediately! (oh by the way it's not very much electricity but I'm not going to explain why or even how much less, and it's probably not even enough to turn on an LED but I'm not even going to mention that)" and then get pissy when people are like "???!??!?!" It's pretty blatantly deliberately misleading and confusing in order to stir up exactly this controversy.

Especially since the effects he's describing are probably (as mentioned in this video) because of capacitance, and are completely dependent on the 1m distance between the wires across the entire span, a constraint he mentions basically once and then never again, and never says explicitly that it's related to the effect.

This video and electroboom's videos are far more educational, and more importantly don't leave you hanging with a bunch of new questions with no resources provided to answer them.

> Especially since the effects he's describing are probably (as mentioned in this video) because of capacitance, and are completely dependent on the 1m distance between the wires across the entire span, a constraint he mentions basically once and then never again, and never says explicitly that it's related to the effect.

YES. This is my biggest gripe with the video. A better shape of wires would be a pair of tangent circles, each one with a circumference of 1 light-second, and a 1-meter section removed at the tangent point. (Hope I'm describing it right. Basically but only the switch and the light bulb 1 meter apart, but get the wires as far apart from each other as possible)

Now would that eliminate capacitance? Or largely so? What amount of current would begin flowing across the bulb at t₀?

After seeing that video and all the reactions, I know more—but not from the original video. My mental model of electricity is still that it "flows along wires", but I now can somewhat separate the movement of charged particles from the energy flux those moving charges propagate. I think.

I actually think he intentionally worked with (some of) these other youtubers. I've been enjoying watching all the "regulars" I follow on youtube challenge his assertions.

It’s not pedantic.

EMI “teleporting” outside of wires is a real world issue that engineers deal with constantly. FCC certification is almost entirely about this phenomenon.

It’s just told in a confusing controversial way.

I'm not an avid Veritasium viewer but from what I've seen this MO seems to be kinda his shtick.

Veritasium is the better teacher. The rest is just jumping on the bandwagon to grab viewerships. Think about it, back in your school days, you have an inspirational teacher that challenge or motivate you to pursue something. Rarely that teacher will spoonfed you with all information. I have many great teachers that explain well. But not a single one of them make it to the list of inspirational. I have 1-2 memorable teacher that really inspire me and they don't exactly explain things exceptionally clearly and all-in-one package. Veritasium is the kind of person that moves needles. Electroboom will be the inspired students to follow-up. The fact that he demo that wind car thing correctly and better than the specialist shows that he is the better teacher.

sorry, veritasium is not / no longer the channel you think it is.

they are not out to teach first.

teaching became second at some point. making views became first and more important. it is totally understandable. (they talk about the team, paying people, etc.) i personally appreciate the honesty. the video they did around the subject should still be around.

This is the youtube generation. Entertainment, clicks and wow factor first (and money of course), facts a distant second.

They really managed to get a success this time: lots of views for this controversial video! But for me, it feels like a lot of credibility capital was spent. I was probably part of the core audience a few years ago.

For me Veritasium lost all his credibility capital by the way he responded to Tom Nicholas’ video about YouTube sponsorships using Veritasium as a case study[1]. In stead of approaching the debate calmly (or better yet, simply ignoring it) he came to the comment section way too defensive, like a lot, basically calling Tom a lair and a bad actor.

Actually that is not quite true, Veritasium lost a bunch of his credibility capital when he made the sponsored content for the self driving cars. I never watched that video as I spotted it was basically and ad and was reluctant to watch his new stuff after that (though I did).

1: https://www.youtube.com/watch?v=CM0aohBfUTc

True. It’s one of only a handful of YT videos I’ve ever left a comment on. In summary, just because something is “wrong” at one scale doesn’t invalidate useful models and workaday theorems at another.

Also, for such a pedantic video his field lines were wrong.

Yeah, the assumption that Derek is 3 steps ahead might be wrong and he might just be wrong.

Well played though that the world thinks he knew his wrongness would spur debate.

Speaks to his earned credibility, but not to his infallibility.

> It’s one of only a handful of YT videos I’ve ever left a comment on.

Which was exactly his point— It's called "engagement".

A long, long time ago, before I realized software makes more money than being an EE(albeit with less life satisfaction), I went to school for EE. I like the Veritasium video for the debate it is spurring, but I really hate his impractical assumptions(funny, since 80% of EE is 1st and 2nd order approximations with 10% tolerances, but I digress). I get that he needs to simply things dramatically because of the audience he's trying to reach, but light year long superconducting wires and a light bulb that turns on with infinitesimal current just bother me. I guess normies wouldn't get that interested by talking about transient EM waves... but the video just leaves a bad taste in my mouth and I understand why EEs are making response videos. I wish he at least mentioned that the power reaching the light bulb would be practically useless. Oh well. Hopefully it spurs a few young minds into sacrificing higher pay for a career in EE or physics.

Here's the link if you're as curious as me https://www.youtube.com/watch?v=bHIhgxav9LY

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