this post was submitted on 25 Dec 2023
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If I remember correctly, Veritasium had few misinformation videos.
Not exactly misinfo but definitely based on some slightly less than honest setups.
Like the speed of electricity video. He was technically correct that his hypothetical instant lighting lightbulb would light up when the first tiny bit of current crosses the gap using EM waves, but it didn't quite account for our general understanding of lightbulbs work and it wasn't adequately explained that the lightbulb didn't act like a real lightbulb, unlike the hyperreality of the rest of the setup in the hypothetical experiment.
I remember this video. Something about if the circuit was astronomically huge, like the wire went to Alfa Centauri and back (so that light would take 8 years to do a roundtrip), and you flick the switch, a lightbulb would instantly turn on - instead of us waiting 8 years.
Was that not true, then? Because I tried to make sense of it, but gave up - and gave him the benefit of the doubt.
So conventional models describe electricity as flowing through the wires at the speed of light, (this model is extremely useful but doesn't accurately describe the underlying mechanism) so it makes sense that it would take 16 years in the aphla centauri example (8 years there and 8 years back) for the information that the switch is closed to reach the lightbulb, and that is what happens irl. The full voltage does take that much time to travel the distance BUT because electricity and moving electrons is more complicated and is carried by the electric fields, some of that electric field reaches across the gap and puts a tiny voltage across the lightbulb, which in his example immediately turns on to full brightness at any voltage difference.
Fascinating. But wouldn't that be against that principle of the traveling speed of information, which happens to be the speed of light?
Let's say that instead of a lightbulb, we have a morse code wire with two stations, one on Earth (and yes, let's ignore that Earth is rotating and constantly moving) and one near Alfa Centauri. If an operator starts punching codes, will the other end immediately receive them?
Oh apologies with a missed detail. The battery+switch and the lightbulb are 1 meter apart and are connected by a wire that is 1 lightyear long.
Assuming that electricity is only carried inside the wire (like our conventional understanding and models expect), yes it does break the speed of light but electricity doesn't actually travel inside the wire but in the electric field around the wire, which gives the wire near the battery to affect the wire near the light and create a tiny voltage difference, thereby nearly instantly lighting the lightbulb that reaches max brightness on any voltage differential.
Thanks! I think I'm starting to understand it now. When the switch is flicked, the field starts doing its thing, whatever that is, and thus electricity begins to flow "in the vicinity" of the lightbulb and the switch. That's why the lightbulb turns on.
Having said that, if there was another lightbulb connected at the opposite extreme of the circuit, say, half a lightyear away, then that lightbulb wouldn't immediately turn on. It will turn on eventually, but like, six months later. Would that be correct?
Yup that's it
Wild! Thanks!