text: "Arrogant" is correct. To a great extent, Edison was hyping up DC power against Tesla's AC power because he had a significant financial stake in the matter. By the 1880s, all electrical power was supplied by Edison's companies (today's ConEd). Imagine having so many wires, transformers, and power generating stations around. Even in that era, the cost could amount to billions of dollars. These are what economists call "sunk" costs (you can't recover them).\n\nTesla's idea to use Alternating Current necessitated an entirely different approach. Tesla was working for a competing company, Westinghouse, which had different equipment. \n\nEdison did slow down progress because DC is inherently more inefficient than AC. DC current is just like the current in a battery circuit. It stays constant. But over long distances, the resistance inerent in all wires (even if they conduct electricity very well) causes much of the power to be lost as heat. To recover the lost power output, step-up transformers are required along the pathways.\n\nOn the other hand, with AC current a high-power current in massive wires produces much less resistance that is lost as heat. The only requirement is that the power be "stepped-down" before it arrives at your house.\n\nEdison had some legitimate claims, however. These are:\n\n-AC has the potential to do more bodily damage. The reason is not because AC current is necessarily higher voltage, because two currents of 120 volts, on average, have the same voltage whether they are direct or alternating. But alternating current is only 120 volts on average, it can actually swing much higher since it is produced as a sinusoid (a wave). When we measure the"average" current we take the average of the peaks. That means that an alternating current can temporarily have much higher voltage.\n\n-AC current requires massive step-down transformers, so you can imagine that if you get a "zap" of some of the massive wires carrying high-power electricity from the power generating plants, you're instantly dead. But few of us have the misfortune to ever come into contact with such high-power lines. They mostly pose a problem to maintenance experts who literally sometimes have to arrive by helicopter to service lines.