The million-monkey method

Thomas Alva Edison is often called an `electrical genius' or `the wizard of Menlo Park' (Edison's labs were in Menlo Park, New Jersey, and later in Menlo Park, California).  It is certainly true that Edison's company either invented or promoted quite a few things electrical.  Edison held an enormous number of patents.  But in my opinion, he was not really a genius at all, at least not with regards to electricity and energy.  He was not terribly well-educated, and his approach -- which he himself described as `1% inspiration and 99% perspiration' -- was something of the `shotgun method': fire lots of small pellets and hope that one of them hits the target.  For instance, when working on the electric light bulb, he had an assistant test over 1000 separate filament materials.  Someone else did all the hard work; Edison just put up the cash, collected the credit, and held the patents.

The alternative

Nikola Tesla, on the other hand, was definitely a genius -- and a nut.  He came up with the concept for three-phase AC as a teenager in Eastern Europe.  (According to a biography I read, the idea just sprang into his head one day.)  He went to an actual university and studied actual electrical theory.  He would decide to build something, work out the details -- usually in his head -- and then build it and it would just work.  He had no business sense at all, though; after coming up with a simple, reliable, reasonably-efficient and sensible method of generating, transmitting, and using electricity, he sold the patents to George Westinghouse.  Today `Westinghouse' is a famous brand name, while `Tesla' is known only for his coils.

The AC/DC wars

In any case, back in the early days of electrification, Edison and Tesla (and of course Westinghouse) became involved in propaganda wars.  Edison held patents on Direct Current systems, while Westinghouse held patents on Alternating Current.  DC was easier for any ordinary uneducated slob to understand, of course -- it required no calculus, nor the sort of `mental vision' of voltage and current flows creating rotating magnetic fields that would spin a motor -- but AC clearly held the technical edge for centralized power generation and long-distance transmission.  Either worked fine for simple applications like lighting (although something called the `Edison effect' made light bulbs burn out at one end and thus not last as long as with AC), but AC's easy transformability made it far more practical.  To use DC, one would have to put a coal-burning generator on every street corner.  Edison no doubt saw his patents becoming worthless, and set out to demonize AC.

The first electric chair execution, held in upstate New York, used AC.  Exactly why, I am not sure.  It is true that AC, especially around 50 to 60 Hz, can paralyse muscles; it causes them to lock up, so that someone who accidentally gets hold of two bare high-voltage wires can find himself unable to let go.  DC tends to cause a more `one-way' contraction.  Either can kill, but without the `locked muscle' effect, it is easier to free oneself of a DC current.  (An old electrician's trick, by the way, is to test a supposedly-dead circuit using the back of the hand, rather than a finger-tip.  If the circuit is still energized, the hand will clench shut, because the finger-closing muscles are stronger than the finger-opening ones.  The clenched-shut hand will tend to jerk away from the wire, rather than grabbing hold of it.  It is an old electrician's trick because the young ones who use it and get shocked live to become old electricians....)

In any case, in what amounted to a publicity stunt, Edison arranged for news reports on the `killer AC' that his competitors planned to string up all over the city of New York.  Despite this, AC was so obviously superior that it won out anyway.