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I bought 1000 meters of wire to settle a physics debate

I bought 1000 meters of wire to settle a physics debate

AlphaPhoenix
8 HN recommenders · discussed 2021–2026
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About this video

AlphaPhoenix builds a scaled-down version of the Veritasium electricity thought experiment using about a kilometer of wire and an oscilloscope. He measures how the signal actually propagates and explains the result.

Why it appears in the archive

HN considers it the best experimental rebuttal and clarification of the Veritasium wire debate, with real measurements.

AI-generated summary and labels from the source dataset; verify important details against the video. Source & credits.

From the Hacker News discussion

jerf · 2023-09 · strong rec

The video in question for reference: [LINK] Interestingly, when I saw that I figured this channel for a goner because he was going to turn to the darkside, but quite contrary to expectations I feel like his channel has actually blossomed since then. His older videos are fine, but often just explaining concepts that you can find a lot of other explanations on, but some of his recent videos have rocked the boat even among physicists and IMHO he was ultimately proved to be correct for them. I particularly point at his videos about how nobody has measured the one-way speed of light ( [LINK] ), which was well-known among people very very deep in the field of relativity but not very well known outside of that (even amongst physicists in other fields, let alone lay people) and the electricity videos he's done in the last year ( [LINK] , [LINK] ) which attracted a whole whackload of "debunking" videos, which were themselves wrong (the best "bunking" video, if I may call it that, is probably AlphaPheonix's: [VIDEO] , since he actually set up the experiment, albeit on a smaller scale). They aren't all of that caliber, but the knot theory video was very good too and not something I've seen a hundred times elsewhere, and the airships video that preceded that one clearly had a high degree of research put into it beyond just the hype.

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moffkalast · 2023-12 · strong rec

Yeah I really liked the AlphaPheonix video[0] where he actually built the thing in a field and explained the entire effect properly. I'm not entirely sure if Derek didn't really understand what he was presenting in that video or deliberately based it on a really misleading bullshit gotcha to troll people and stir debate for clicks, and neither reflects very well on him. [0] [VIDEO]

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reaperman · 2024-07 · strong rec

[VIDEO] AlphaPhoenix did an amazing experiment to measure the speed of electricity FWIW. His other videos are incredible as well and explain EM physics in an absolutely outstanding way.

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pja · 2022-01 · rec

His presentation is not very clear & imo the way he answers the question is not actually helpful in actually understanding what’s going on, but he is correct that current will flow in the far side almost immediately. As is made clearer in the documents he shared which contain his discussions with actual physicists, that current will be much smaller than the final current that flows all the way round the circuit, but it is there nevertheless. (In fact that current will initially flow whether or not the two halves of the flat ring are connected - if you think about it things have to work like this, because the middle of the system cannot “know” whether the far ends are connected until light has had time to get there & back. Relativity is absolute.) Take a look at the video made by YouTuber AlphaPhoenix where he constructs the entire thing on a smaller scale and demonstrates the effect with an oscilloscope: [VIDEO] One way of viewing what’s going on here is to consider the two sides as a pair of large dipole antennas. When the switch (or in AlphaPheonix’s case, a transistor) is turned on, a pulse of electrons is pushed down one antenna, setting up a transient wave in the electromagnetic field around it which induces a current in the opposite direction in the “receiving” antenna on the other side. This happens regardless of whether the wired are connected in a loop or not! Physics is great.

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bertil · 2023-04 · rec

The author has a fascinating video (part of a wider effort of many science YouTubers) that tries to clarify all that. [VIDEO] I’m actually not sure if that makes his explanation more accurate because it’s informed by that, or more regrettably forced metaphor. But the whole series of videos from different creators is worth watching if you want to understand the whole “electrons are moving” thing.

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Manuel_D · 2023-07 · rec

Not really in the intuitive sense: [LINK] Someone actually went out and tested this: [VIDEO] The electric field is very tightly constrained around the wire. The amount of energy that reaches the light through the gap is incredibly small, not nearly enough to turn on a real light bulb. The bulk of the energy does indeed have to take the path through the wire. I find that video usually leads people to an even less correct understanding than the marbles-in-a-tube analogy. The Veritasum video can essentially be summarized, "fun fact: two parallel wires act like an antenna, and an extremely small amount of energy reaches the other end before the rest of the energy takes the long path through the wire.

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Spivak · 2025-02 · rec

Yes, you can see one of the best people do a demonstration of it [VIDEO] It's close enough to c that you should just use c but it can be observed that it's less.

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sbuttgereit · 2026-04 · rec

Looking at the discussion below this comment, I'd just add this video by AlphaPheonix: [VIDEO] Good discussion in the comments there as well.

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