They take all paths weighted by resistance.
The pepper demonstration in the video is a good analogy to show how the resistance information of every possible path (or, really, stub) is "back-propagated" to the branching point. No, it's not a perfect description of what is really going on, but I dare say there's no such thing. Just better and better models.
If I have a wire that connects from (+) to (-) on a battery, and a dozen wires that branch off of (-) and go nowhere, how does the current "know" not to waste time trying each of those stubs? This video explains that.
You're still saying "path of least resistance" though.
A very important part of the answer is that it doesn't find it. All paths carry electricity.
So "take all paths" isn't begging the question, it's correcting the question, and "weighted by resistance" isn't begging the question, it's giving a pretty easy answer to anyone that understands the concept of "resistance" in a non-electrical sense that some paths let things through more easily than others.
And if you have a bunch of stubs, the electricity does go onto them. It just gets stuck at the end.
Or in other words, the comment had multiple points and I chose to respond to one of them.
Yeah, I think you're correct here. I'll clarify what I meant:
The title statement is "How electrons find the path of least resistance", and what I replied to said, "They take all paths weighted by resistance".
The underlying question remains: how do the electrons "know" what the weights are? When a new charge carrier enters the maze, how does it "know" that "turning left" will be an easier trip than "turning right"? How do most of them end up taking the express lane?
I guess the original comment wasn't meant to answer this question, but rather rephrase it to be a more accurate question in the first place. I misread it as an answer.
Question: when you observe water flowing on a flat surface do you see the water droplets freely separating from each other all over the surface until it's kind of evenly distributed or do you find the droplets tend to kind of follow or stick to one another?
For example, imagine you have nice trickling stream of water and that stream comes near a droplet, does the droplet join the stream or does the stream miss the droplet?
Does the new "charge" in the maze join with an existing stream or is it starting with a neutral maze and has to find the exit again?
It doesn't need to know that it needs to turn left or right, it just needs to go with the lazier option which happens to be the less resistant one.
From my point of view, finding the path of least resistance does require some kind of "knowing", but taking every path doesn't take some kind of "knowing".
The electrons just push. Like you can push something across a surface with varied friction. Or you can try to walk down paths with different amounts of obstructions. And when they get through faster, they make room for more faster.
Why resistance exists and varies is a valid question, but it's not one that everyone will have. Some people need that explanation, but some people just need "It takes every path with equal vigor."
So the original comment was an answer to the question. Not the answer everyone needs, but a valid answer for many people.
Also a nice comparison is how lightning does actually find a single path, because the current flow makes the air it touches more conductive in an aggressive feedback loop.
How does water "solve" a maze to an open tap?
Water doesn't actually "solve" a maze either https://youtu.be/81ebWToAnvA
And I put "solve" in quotes precisely because it does no such thing.
But a water molecule interacting with pressure gradients and waves is about the best eli5 or even eli18 that I've seen, with both particle and wave representations.
But maybe that's just because I'm a hydraulics engineer and "get it."
I love to argue the technical stuff as much as anyone, but the underappreciated aspect and skill of any engineering is eyeballing cost/benefit of any expenditure.
Be it sizing elements of finite analysis, or sizing an analogy.
Also light doesn't act like electricity or water, it just bounces at the reflection angle. There is no volume or pressure. Also there is no such thing as a light 'particle'. That is an abstract concept to make simulation easier.
> You're conflating electrons and electromagnetic radiation.
Isn’t that one of the main points of quantum physics? Light does apply pressure. Also photon exists?
Do you think quantum mechanics says that light is made up of electrons?
That would be like saying sound and water are the exact same thing because water going through a hose makes sound.
Light does apply pressure.
On the other hand, no it doesn't. If you shine light into a tube, it doesn't fill up with light until the tube blows apart. This is what is being talked about in this thread, so try to understand that context.
Also photon exists?
Are you asking if photons exist? Electromagnetic radiation is magnitude of frequencies over time. There are no individual packets of light just like there are no individual packets of sounds. Photons are a useful idea in simulations because you need to sample specific paths.
No, only that electrons can exhibit light-like behaviours (e.g. interference patterns).
Light and pressure: https://en.wikipedia.org/wiki/Radiation_pressure
I don't see what that proves. If you pour water or CO2 or whatever into a normal tube, it doesn't fill up until the tube blows apart, it overflows. And you can easily show those fluids exert pressure.
To blow up a tube you need to have enough pressure at the fill valve. And if you do that, you can blow up a tube with light. It just happens to be hard to concentrate light that much.
you can blow up a tube with light.
Show me an experiment where light exerts itself physically on other light through being constrained to the extent that it finds the path of least resistance.
Really, this is the epitome of a hacker news discussion where there is something reasonable being twisted into absolute nonsense with excessively convoluted arguments.
You can't just pour electrons into something and blow it up either. So what does it prove that you can't pour photons into a tube to blow it up?
If you want the analogy to electrical flow then it's not trying to blow things up, it's having different sized holes for light to go through, and some scattering in the nodes.
Also my edit to the previous post was late so I'll move it here:
> There are no individual packets of light just like there are no individual packets of sounds. Photons are a useful idea in simulations because you need to sample specific paths.
Sound is carried by individual particles.
Light is quantized (aka packets) unless you happen to have an alternate explanation for the ultraviolet catastrophe?
Sound is carried by individual particles.
Electricity is carried by a conductor like copper, but electricity is not copper and sound is not a particle.
Electromagnetic radiation is magnitude of frequencies over time. There are no individual packets of light just like there are no individual packets of sounds. Photons are a useful idea in simulations because you need to sample specific paths.
https://en.wikipedia.org/wiki/Electromagnetic_radiation
This whole thread is about finding the path of least resistance in a pragmatic sense, not some abstract theory that you can't demonstrate. Even the wikipedia article talks about 'light particles' as an 'alternate view with no mass'.
That's true of light too.
Not just shining in a weak source indefinitely. You need a powerful source. Just like with electricity or fluids.
They behave the same.
Photons have no rest mass which is extra abstract. They do have mass, and them having mass is not abstract. And you didn't explain how to resolve https://en.wikipedia.org/wiki/Ultraviolet_catastrophe without discrete packets.
This stuff is pretty easy for someone to demonstrate with electricity or fluids, so show me it being done with light.
I'm not trying to be contrarian, I think you brought up a weird example to complain about and you got rightfully downvoted for it (not by me).
Also if you want to read my other comment chain on this thread, I would not say that electrons do find the path of least resistance. They follow every path, and so would light.
This was all about taking the path of least resistance, so show me anything that shows light doing that instead of just bouncing off the reflection angle.
Simulations are around 50-60 years newer than the discovery of the photon.
Now, in QFT, I believe the photon itself is not fundamental, the electromagnetic field is fundamental. But even then, fluctuations in that field happen only in integer multiples of the energy of the photon.
But if you are coming at this from a more old-school QM or even classical mechanics perspective, where fields and particles are different things, then the photon is just as much a particle as the electron and the quark are.
That is, in certain experiments, light behaves like a classical wave (for example, double slit experiment), while in other experiments, it behaves like a classical particle (photoelectric effect [0]).
If your theory is simply that light is a classical wave (EM wave, obeying Maxwell's equations), then you should expect that shining a bright low-frequency light over a surface will eventually dislodge a number of electrons equal to the number of electrons dislodged when a dim high-frequency light is shone on the same surface. However, in real life experiments, this doesn't happen. Instead, no electrons are dislodged by the low-frequence light regardless of intensity, while some electrons are dislodged by the high-frequency light even at very low intensities.
The explanation for this phenomenon is that light consists of individual photons. Each individual photon has an energy that corresponds to the so-called frequency of the light. When a low energy photon hits an electron, nothing happens - so, regardless of how many low-energy photons you generate, nothing will continue to happen. Conversely, when a high-energy photon hits an electron, that electron is dislodged. So, even a sparse beam of high-intensity photons will dislodge some electrons. Even more impressively, you can directly count the number of electrons dislodged and compare to the number of photons contained in the beam, and you will find that they are actually equal, proving even more that the photon is a particle in this type of experiment.
There is no way to explain this phenomenon if you try to explain light as simply a wave in the classical EM field.
Also, crucially, space isn't quantized, and sound represents the variation of some particles' position in space, so its frequency and so on can take any value - again unlike the EM field.
It is very interesting. But that doesn't make it good at teaching.