It seems quite inefficient, as the shortest distance (and, therefore, duration) to traverse is a straight line.
In: Physics
It’s interesting that you say that the shortest distance is also the shortest time because in reality it isn’t! This is one of the most interesting concepts in physics imo. The path that minimizes distance is not always the path that minimizes time. Take a simple example of a ball rolling down a straight ramp. You have 2 positions, start and finish and then the path in between. It turns out that the path that minimizes time is a curve that travels between the two points called a brachistochrone. There are great youtube videos on brachistochrones that talk more about the details!
Beyond mechanics, light also exhibits this very strange behavior. When traveling through two or more different mediums light will refract (fancy word for bend) to ensure that the path that minimizes time is taken. The overall path is not a straight line, but rather 2 separate straight lines so distance is not minimized, but you better bet time is!
Pierre de Fermat is a famous natural philosopher, mathematician, brilliant guy who developed the Principle of Least Time. It’s actually possible to derive all of classical mechanics from this very unique and groundbreaking theory. Keep in mind also that Fermat developed his Principle of Least Time somewhere around 1650-1660, before Newton even published Principia!
Electricity doesn’t travel the shortest distance. It travels the path of least resistance. Air has a very high resistance. Electricity needs a charge carrier to travel. Atoms of air can carry charge but are relatively far apart compared to water (tangent: water doesn’t conduct electricity either since it is charge neutral, salt water, however, does conduct electricity). Small changes in the density of air can have a large impact on the resistance of air. Also important is what is in the air, dust, water, etc., and how conductive those substances are. Air is not uniformly distributed and is not uniformly filled with dust and water. These small changes in the distribution of density of charge carriers cause the lightning to seek out the path of least resistance, a zig zag, tree like path.
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Electrical Engineer here…
A few thing need to be understood first, there is no such a thing as a electrical insulator, there are just some materials that are really bad at conducting electricity, that we can consider them as insulators in the amount of energy that we normally use…
But, at high enough voltages, those insulators will end up conducting electricity (there are many technical terms here that are not needed in a ELI5).
Air is one of these materials… Thank God it is a really bad conductor usually, or we couldn’t have transmission lines. But when the voltage gets really high the air will conduct, as the air is not homogenic, it will have some parts that will conduct easier, and the current will find it’s way through the air (current is electrical energy traveling, or the elctrons moving). That’s what happens when you see blue sparkles when you use an electrical switch, this is called and electrical arch.
The same thing happens with a lightning, but at a much higher voltage (and thus a much higher current) and at a much higher distance, and so the curves the current makes are more visible than in a short electrical arch.
If I used a wrong terminology it’s because English is my second language, and some terms might get lost in translation… Where I said electrical arch, it’s probably electrical arc
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This guy goes into it in-depth: https://youtu.be/JXhif3E3l2s
He’s also a fantastic storm chaser if you’re interested in that.
Here ya go, a [relevant XKCD, but this time a What If topic on lightning](https://what-if.xkcd.com/16/)
why does it seemingly travel straight for a while of time before switching direction though? It seems like if it was always searching for the path of least resistance it would have a more fluid movement?
There are “stepped leaders of highly charged, ionized air columns headed toward the Earth along with tendrils of positively charged air columns reaching toward the cloud from the Earth. When two of them meet, the electrical path is complete and lightning strikes. The repeated flashes are the stepped leaders draining into the ionized air column. At least that’s my theory.
The lighting does not have a conscience, basically.
Imagine you want to go to X city, Y hundred kilometers away from yours. No map, no asking anyone, just knowing the general direction and looking at signs, taking shortcuts etc.
You wont know what the best path was, you would just take the easiest path to next place in sight. Theres no way you know that escalating that mountain and jumping down to that lake would be faster than following the road.
In the same way, the energy would flow towards wherever theres less resistance over and over and over, creating the “zig zag”
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