Nikola Tesla inspired a lot of good in the world, but some of his inventions and ideas could have potentially put an end to civilization. One of the most dangerous inventions that Tesla played a role in was the creation of the death ray. In the wrong hands, the death ray could have wreaked havoc on everything and everybody, and that was the intention of the Imperial Japanese Army during World War II.
Japan took the unfinished idea and in 1939 began production of a death ray which cost the government upwards of 1 million yen to make. The future-Nobel Prize winner Sin-Itiro Tomonaga and was involved in Project Power and was reported to have said that the death ray had the capacity to kill from distances of up to half a mile. Unfortunately for Project Power, and fortunately for the rest of the world, the target had to remain still for between 5 and 10 minutes in order for the doomsday device to be effective.
In addition, the weapon wasn’t as appealing as many speculated it would be. Basically, the “death ray” comprised of a magnetron and a 75-foot-mirror, making it an impractical weapon to take to the battlefield. Despite being an unrealistic piece of weaponry to haul to war, after testing and modifications, the weapon was deemed successful in killing rabbits, marmots, and monkeys. The device was even successful in completely stopping a car engine from running, provided that the hood remained open. One of the scientists involved in Project Power even stood in front of the ray beam for less than a minute. The effects he experienced included dizziness and fatigue which lasted for 24 hours.
The death ray was never wheeled out into battle, and the current whereabouts of the prototype are unknown, though many speculate that the weapon was thrown into a lake.