Imagine the following conductive structure built outside: A || || B|_____C || || ---------------------- Basically, a T-shaped piece of metal, with one end stuck in the ground, one end pointed into the air (A), and one end horizontal, parallel to the ground (C). Let's say lightening strikes the structure at point A. Current flows down until it arrives at point B. Here it has to make a 'choice', and my understanding is that all of the current proceeds to the ground. I.e. a measurement at point C will never show any electric current there (assume we're in a vacuum so the ambient 'air' is not conductive). How does the electricity 'know'--without ever investigating the horizontal element--the way to ground? When the first element of current arrives at point B, why does it automatically proceed to ground? How does it 'know' this is the 'right' way to go? Thanks in advance.