I know Tesla's star has been rising in recent years, and Edison's reputation has taken a bit of a beating as culture has moved against aggrandizing the powerful few. I admire Tesla's brash genius, don't have much interest in defending Edison, and all of this is getting pretty far off topic, but a few points:
Tesla didn't discover AC electricity. As with everything, AC came from a long series of small discoveries but if I wanted to pick a key player in AC power I'd pick
Faraday in the early-mid 1800's. You can be darn sure he also got a few ideas from something he saw elsewhere (Orsted, for example).
Tesla obviously did a lot with AC power (and in the related field of radio), but Westinghouse was already working with it by the time they bought Tesla's patents. Tesla's main contributions to Westinghouse were in support of a key application for AC: a motor. Electricity was driving two key uses at the time: light and work. Arc lamps were providing most of the electric light and motors at the time were DC. Tesla invented an AC motor and a way of more efficiently delivering AC power (
polyphase AC). Again, along with contemporaries and built on earlier ideas.
Edison was a hard nosed industrialist but I don't see much evidence he was a sociopath or psychopath. By all accounts, one of Edison's key arguments for encouraging DC distribution was that it was lower voltage and safer. People at the time were dying due to accidental electrocution in part because AC transmission lines were much higher voltage, but mostly because electricity was under-regulated, poorly understood by laymen, and badly installed. He was arguing that the loss of life was an unreasonable cost for the improved efficiency of high voltage AC. Yes, he had patents that gave him an economic advantage if DC was chosen, but he also had key patents in AC power distribution.
Edison opposed the death penalty and refused to consult on the development of the electric chair. He refused contracts for offensive weapons, and
claims to have never invented a weapon that kills. "Nonviolence leads to the highest ethics, which is the goal of all evolution. Until we stop harming all other living beings, we are still savages."
Tesla was actively developing guided torpedoes and a "
death ray" that he pitched to all of the US, the UK, and the USSR.
Edison wasn't killing puppies. That was part of a campaign by a different guy (
Brown) who also seemed, in part, motivated by the dangers of high voltage wires strung throughout cities. There is some evidence that Brown was getting some support behind the scenes from Edison's company, but also from Westinghouse's other major competitor at the time. I don't see any evidence of Edison the man (separate from the actions of the company) endorsing the killing of animals in this way.
The animals being used in the demonstrations were strays or would have been euthanized for other reasons. Before the adoption of the electric chair, electricity was already being used as a "more humane" way of euthanizing stray animals. Many places still euthanize strays today. Electrocution was also adopted as a "more humane" alternative to hanging for humans.
The elephant had nothing to do with Edison or Westinghouse or Brown for that matter. It was the euthanization of a problem circus elephant who was simultaneously poisoned, strangled and electrocuted like a modern day
Rasputin.
I find it distasteful that these demonstrations were public and used for corporate propaganda, and there were protests against them at the time. This was also 140 years ago. Just 100 years before that, we were
taking people's heads off in the public square. Many animals are still killed for corporate research, scientific experimentation and human safety testing and
we still use electrocution as a form of execution in places today-- all of which I also find distasteful to think about.
Edison apparently stiffed Tesla on a promised bonus-- not cool. He probably also took credit for the work of his underlings-- also not cool. That said, professors today still put their names on papers published by their grad students.
Was Edison a great guy? Probably not. Was he a monster? Probably not.