Death-rays were a theoretical electromagnetic weapon popular between the 1920s and 1930s for their supposed ability to remotely power devices and destroy living creatures. Inventors like H. Grindell-Matthews, pictured below, claimed to have invented a "mystery ray apparatus," capable of paralyzing internal combustion engines of airplanes and automobiles with an invisible beam. Although most experts dismissed the claims of Grindell-Matthews and his counterparts, which included Nikola Tesla, the idea of a death-ray nevertheless captured the imaginations of a public already thrilled by H.G. Wells' fictional descriptions of extraterrestrials who could zap the world into oblivion.
Like many leading scientists, we were skeptical that a "diabolical beam" could exist, let alone that it would be powerful enough to wipe out human civilization. At the same time, we acknowledged a related technology, wireless power transmission, could make life easier without "dealing electric death" and contributing to global warfare.
Read the full story in "Man's Most Terrible Invention"