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 Hacker News points people here: HN considers it the best experimental rebuttal and clarification of the Veritasium wire debate, with real measurements.
“Yeah I really liked the AlphaPheonix video[0] where he actually built the thing in a field and explained the entire effect properly.”HN comment, 2023
“the best "bunking" video, if I may call it that, is probably AlphaPheonix's”
Best rebuttal to the Veritasium wire video, with a real experiment
Full comment
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: this 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.
Strongly recommendsmoffkalastDec 2023
“Yeah I really liked the AlphaPheonix video[0] where he actually built the thing in a field and explained the entire effect properly.”
Built the experiment in a field and explained the effect properly
Full comment
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] this video
Strongly recommendsreapermanJul 2024
“AlphaPhoenix did an amazing experiment to measure the speed of electricity FWIW.”
Experiment measuring the speed of electricity
Full comment
this 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.
RecommendspjaJan 2022
“Take a look at the video made by YouTuber AlphaPhoenix where he constructs the entire thing on a smaller scale”
Small-scale demonstration of the effect with an oscilloscope
Full comment
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: this 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.
RecommendsbertilApr 2023
“The author has a fascinating video”
Clarifies how electricity moves in circuits as part of creator series
Full comment
The author has a fascinating video (part of a wider effort of many science YouTubers) that tries to clarify all that. this 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.
RecommendsManuel_DJul 2023
“Someone actually went out and tested this”
Actual test showing energy mostly takes the wire path
Full comment
Not really in the intuitive sense: link Someone actually went out and tested this: 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.
RecommendsSpivakFeb 2025
“you can see one of the best people do a demonstration of it”
Demonstration of electrical signal propagation speed
Full comment
Yes, you can see one of the best people do a demonstration of it this video It's close enough to c that you should just use c but it can be observed that it's less.
RecommendssbuttgereitApr 2026
“Good discussion in the comments there as well.”
Experiment on electricity propagation with good comment discussion
Full comment
Looking at the discussion below this comment, I'd just add this video by AlphaPheonix: this video Good discussion in the comments there as well.
Cites itYetAnotherNickDec 2021
“This guy performed the same experiment using a km long wire and measured the voltage in oscilloscope.”
Km-long wire experiment measured with oscilloscope
Full comment
This guy performed the same experiment using a km long wire and measured the voltage in oscilloscope. this video
Cites itautokadMar 2022Full comment
I believe this is the same video, the author theorized (probably correctly) that it was because there was residual 'power' on the wire, as it acts like a giant capacitor, among other things. this is because the wire that immediately showed up was extremely small and dissipated very quickly. this video
Cites itvoidwtfNov 2022
“the discussion that arose between AlphaPhoenix and Veritasium YouTube channels concerning the speed of electrons along a closed loop of wire”
Full comment
This sounds similar in some ways to the discussion that arose between AlphaPhoenix and Veritasium YouTube channels concerning the speed of electrons along a closed loop of wire. this video With a relevant illustration at 9:41 at where I think these topics intersect conceptually.
Cites itkragenSep 2024
“the result is more complicated than just a single time delay”
Experimental results showing a more complicated signal than a single delay
Full comment
well, the truth turned out to be quite complicated; see also this video and link . the result is more complicated than just a single time delay, and the details of the experimental setup (like the wire diameter! and load impedance relative to transmission-line pulse impedance) matter a lot. in alphaphoenix's first experiment, putting 5 volts into a kilometer of wire, he got 0.2 volts across his resistor immediately, then after about 1.6μs, a jump up to about 2 volts, and then a gradual rise to 1.7 volts, some overshoot peaking after another 1.6μs, and then settling back down to the 1.7-volt level (derek's results in the linked video, which incidentally links to one of the two i linked above, were quantitatively different but qualitatively similar) the really unintuitive thing about this i think is that people think of electrical energy as flowing inside wires, when actually almost all of it flows around the wires, as veritasium explained quite ably. this is something people doing high-speed pcb layout have to deal with a lot in order to avoid emi problems as i understand it, derek has a ph.d. in physics, or actually in physics education research link . that doesn't mean he knows everything about physics, but generally my experience with people in ph.d. programs is that they're good at listening to counterarguments and admitting when they're wrong, and also seeking out experts before publishing (i think the veritasium video does contain a minor error in that it says electrons
Cites itperpetuallunchJul 2026
“AlphaPhoenix’s response to Veritasium”
AlphaPhoenix's response to Veritasium
Full comment
One cannot simply bring up Veritasium without also honouring his arch nemesis ElectroBOOM. link Others that deserve a mention: styropyro link The Angry Pixie herder, Uncle Bumblefuck aka AvE: link And that guy with the multi gigawatt 150,000 volt Lorentz Cannon: link I’m sure I forgot someone? AlphaPhoenix’s response to Veritasium: this video
