I’ve always heard that electricity follows the shortest path – for instance, lightning will use your body for a conduit if you’re the tallest thing around. How exactly does that work?
In: Planetary Science
It doesn’t — not really. Electricity starts out by taking *all* paths, and over (a very short) time, the electromagnetic field surrounding the paths in question “probes” the paths to determine how it should settle down. AlphaPhoenix has [a rather good video](https://youtu.be/2AXv49dDQJw) where he goes into this in some depth.
Imagine electricity like the flow of water on a river. Everytime it encounters an obstacle the water explores the surroundings for the path of least resistance. This is the same for electricity: longer path, more resistance, and vice-versa.
It doesn’t know the shortest path. It tries all possible paths. The path with the least resistance will get the most current.
Imagine a room full of people who are all crashing into each other and crashing off of the walls. At one end of the room is a wide open garage door, at the other end of the room is a narrow door that’s only wide enough for one person. Which door do you think more people will get bounced out of, the little door or the big door?
It’s sort of like how water flows downhill – the water is pulled by gravity in all directions, but streams form where there isn’t stuff in the way. Electricity is caused by the movement of electrons. The electrons don’t know which path is the shortest, nor do they act collectively. Each one just tries to move away from negative charges and towards positive charges. More of them can flow through a conductor so they collectively end up taking the path of least resistance.
Lightning is kind of a special case though because air is a very poor conductor, until it is ionized, when it becomes a very good conductor.
So lightning is a kind of complex process that involves electrons moving into the air and then suddenly forming a conductive path when they find a connection to the ground
Imagine you’re sitting in traffic. There are three lanes in front of you, all full of cars. You don’t know what’s at the end of the road causing the traffic jam, and honestly you don’t really care. but from where you’re sitting you can see that the rightmost lane is moving the fastest. So you obviously get in that lane, because it will get you to where you want to go faster than the other paths.
Electricity is the same way. The flow of electricity isn’t one electron running the entire path at once, it’s a huge line of electrons that can’t move until the electrons in front of them move first. Each electron is “looking” only at it’s immediate vicinity, and making it’s “choice” of path based on how the electrons in front of them move. In this analogy, your body is a shortcut to the end of the road that flows much faster than just empty air. The electrons immediately next to your body flow through the shortcut, and the electrons immediately behind them just follow.
Imagine I’m pushing water into a straw, and I’ve blocked off one end. Water doesn’t go anywhere, because I’ve blocked it. Now imagine I unblock the end. Water squirts out! This is the easy case.
Now imagine I’ve put a fork in the straw so there are 2 ways out. I block both ways out and push water in. Where’s it go? Nowhere. The way out is blocked. Now imagine I unblock 1 of the 2 forks. We’d see that *some* water tries to go down the blocked fork, but it gets blocked and stops. *Most* of the water goes down the unblocked 2nd fork because it can’t fit in the blocked fork anymore.
That remains true even if we make 100 forks. Water will go down as many paths as we give it, but if the way out is blocked it will fill that space. New water will try to go that way, but the water that’s already there will block it so it’ll try somewhere else. If any path is unblocked, the water that takes that path will get to pass. If many paths are unblocked, some water will go down each path.
Electricity follows those rules. It doesn’t “know” or “think”. It just is, and if you think through the Physics involved this is the only way it *could* work.
it doesnt, it takes all paths. lightning is “trying” to use anything as a conduit. You’re MORE LIKELY but not guaranteed to get struck than something shorter because you there’s less distance (less resistance) for the electric charge to cover.
a tall person in a large group of people would be less likely to get struck by lightning than someone shorter but off standing on their own. lightning “likes” tall pointy objects that are isolated. the simple explanation there is that there are less possible paths it can take.
Imagine if I have a long chain, like a ship anchor chain, and it’s all just bundled up in a messy pile. This is like a bunch of electrical charge.
Now imagine I pull on one end of the chain, and run very far. I’m pulling the chain from a hundred yards away, but looking at the pile, chain links are coming out of it and moving toward me. How does each link of the chain “know” to follow where I’m pulling? It’s the same principle; all the interactions are happening locally, but it’s following a chain, with the pull being the voltage source.
It tests all paths and eventually one path connects and that’s generally where the flow will go.
[I could go on to explain it, however, a visual example will get the point across far better](https://youtu.be/qQKhIK4pvYo?si=BrdpnvIhWWP0lMhu&t=299)
It doesn’t. Look at videos of lightning. You don’t just see a straight line to the ground, it forks a bit.
Not a meteorologist but once it finds the way, if lightning strikes multiple times, it would now “know” the shortest path because the air is ionized making it easier for lightning to flow in roughly the same path.
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