Future Tense

The Art of the Death Ray

Humanity’s hoax-ridden quest to invent the ultimate weapon has given us everything but—from radar to a likable member of the Trump family.

A death ray shooting from a laser gun.
Photo illustration by Slate. Photos by Getty Images Plus.

Excerpted from Lasers, Death Rays, and the Long, Strange Quest for the Ultimate Weapon by Jeff Hecht. Out now from Prometheus Books.

The ancients didn’t understand the nature of lightning, but they knew and feared its power. To them, lightning was the first directed-energy weapon, hurled by the gods to smite those that annoyed them. The idea of wielding such a weapon has captured imaginations ever since. The term “death ray” was coined in the late 1890s by journalists reporting about the unsubstantiated claims of a man named John Hartman, who had served as an engineer in the American Civil War. Hartman boasted that he had modified a searchlight so that it could guide electricity through the air, and that his electric gun could be set to stun or kill a rabbit 50 feet away.

Death rays became modern myths, updated versions of the bolts hurled by ancient gods, born more than a century ago at a time when scientists were puzzling over new discoveries from X-rays to radio waves, inventors were seeking new weapons of war, and storytellers were looking for thrilling new ways to entertain their audiences.

The laser is a newcomer, invented in 1960 by Theodore Maiman. He had high hopes for uses of his new discovery in research, communications, industry, and medicine when he announced it, and was dismayed to hear that newspaper headlines were mostly variations on “Man Discovers Science Fiction Death Ray.” In time the laser would perform vision-saving eye surgery, enable high-speed internet transmission, weld sheet metal, and do many other things that its inventor could not have imagined. But after 60 years, the invention has yet to become what military strategists around the world once pursued with laser-like intensity: a lethal ray capable of zapping enemies and their weapons into oblivion from thousands of miles away.

A serious quest for a death ray that could stop war began soon after World War I ended. Air attacks had become a major worry. During the war, German zeppelins and winged aircraft had raided Britain 103 times, killing 1,413 people. Laboratory tests showed that high voltages and intense electrical and magnetic fields could affect engines, and military leaders hoped to extend those effects to stop planes. “Under the attack of these electric waves the airplane will fall as though struck by a thunderbolt, the tank will burst into flames, the dreadnought will blow up, poison gas will be dispersed,” wrote French army chief of staff Gen. Marie-Eugène Debeney in 1921. France worried that Germany had already developed such weapons after a series of French commercial flights over Germany had to make emergency landings in 1923.

Military leaders hoped new science would yield new weapons, perhaps even an ultimate weapon. Technology was advancing much faster than in the 19th century. Relativity and quantum theory were revolutionizing physics. “We have X-rays, we have heat rays, we have light rays. H.G. Wells in his War of the Worlds alludes to the heat rays of the Martians, and we may not be so very far from the development of some kinds of lethal ray which will shrivel up or paralyze human beings if they are unprotected,” wrote British Gen. Ernest Swinton in 1920.

Pulp magazines covering new science and technology proliferated, and the border between fact and fiction could be hazy. Young inventor and entrepreneur Hugo Gernsback founded the publication Modern Electrics in 1908, then sold that and in 1913 founded Electrical Experimenter, which Nikola Tesla wrote for. The inventor’s electric discoveries are still used today in short-range wireless systems, but he fell short of cracking the code on long-range wireless transmission. Still, these magazines looked toward a bright electrical future. They published speculative fiction as well, and in 1926 Gernsback launched the world’s first science fiction magazine, Amazing Stories.

This new world eager for new technology and news about it was primed for someone like Harry Grindell Matthews when he arrived with plans for a death ray in 1924. Born in England in 1880, Matthews served in the Boer War, during which he grew intrigued by wireless communications.

In December 1915, Matthews demonstrated wireless technology for remote control of a powered model boat and for exploding mines to the British Admiralty. After working on military projects during the war and later developing an early motion picture sound system, Matthews had a credible track record in invention and engineering by the early 1920s. That helped him get a hearing when he started talking about energy-beam weapons in early 1924. Word reached Winston Churchill, who asked his scientific adviser to check out “the man who is said to have discovered a ray which will kill at a certain distance. … It may be all a hoax, but my experience has not been to take ‘no’ for an answer.” In March 1924, Matthews talked with the Air Ministry about his invention but said he was not yet ready to demonstrate it. In May a New York Times correspondent conducted a lengthy interview with Matthews about his “diabolical rays.”

The inventor was elusive about the details, but he did say that the rays could direct an electric current through the air for up to four miles, and predicted that the range could be doubled. His surviving notes say the two key parts of the system were a specialized electrical generator and a carrier beam that Matthews described as a “searchlight” like that on a lighthouse. The beam acted as a conductor to direct the electrical current and deliver its destructive punch, much like John Hartman’s alleged death ray design. It could not destroy ships, because they were grounded by the water, Matthews said, but it could “put the ships out of action by the destruction of vital parts of the machinery and also by putting the crews temporarily out of action through shock.” Airplanes, being isolated in the air, could be totally destroyed.

The paper also ran a full-page spread explaining why scientists doubted Matthews’ statements—and the quest for a war-stopping weapon more broadly. Michael Pupin, who headed the Department of Electro-Mechanics at Columbia University, said it was nonsense to believe that such a weapon could succeed even if it worked. “You can’t make war so frightful that men will shrink from it. … If a ray could be discovered which would reduce all motor-driven trucks, tanks, airplanes and battleships to scrap-iron, then armies might be obliged to go back to hand-to-hand fighting. But they would fight just the same.”

Growing skeptical of his claims, the British Air Ministry offered Matthews only modest support until he could disable a small engine supplied by the government, a way for them to be sure Matthews wasn’t rigging the test. He declined this proposal but continued talking with reporters and promoting his invention, even shooting and starring in a silent film titled The Death Ray. One segment featured Matthews sitting at a desk in a white laboratory coat, and shows the “death ray” light a lamp and explode gunpowder.  Matthews soon went bankrupt, became the fifth husband of rich Polish-born opera singer Ganna Walska in 1938, and broke up with her before he died from a heart attack on September 11, 1941.

After Matthews, the British Air Ministry decided to take a more pragmatic approach to dealing with would-be inventors pitching their death ray schemes. They offered a bounty of 1,000 pounds sterling to anyone with a ray weapon that could kill a sheep 100 yards away. Passing that simple test presumably would have earned the successful inventor the bounty as well as an invitation to talk with ministry officials, though no one ever did.

But aerial bombing continued to worry Britain. “The bomber will always get through” whatever defense exists, warned Stanley Baldwin in 1932, between his terms as prime minister. “The only defense is in offense, which means that you will have to kill more women and children more quickly than the enemy if you want to save yourselves.” Churchill in 1934 urged rearming Britain and raged against the “cursed, hellish invention and development of war from the air.” Unless science could offer something new, Britain was likely doomed to defeat in the next war.

Henry Wimperis, director of scientific research at the Air Ministry, started exploring the options and asked Robert Watson-Watt, who operated the Radio Research Station of the National Physical Laboratory, if “damaging radiation” from a death ray offered much prospect for defense. Watson-Watt didn’t think much of the idea, but he was a careful man, and to check his opinion he instructed a subordinate, Arnold Wilkins: “Please calculate the amount of radio frequency power which should be radiated to raise the temperature of eight pints of water from 98 degrees F to 105 F at a distance of five km and a height of 1 kilometer”—a circuitous way of asking how much radiation was needed to heat a pilot’s blood to an unhealthy temperature.

Wilkins quickly understood the reason for the question, and his calculations showed that it wasn’t practical. Watson-Watt was not surprised and asked what else radio waves might be able to do. Wilkins recalled that radio receivers often picked up noise when planes flew nearby and wondered if it might be possible to detect planes by reflecting radio waves off them. Watson-Watt jumped at the idea, and existing radio technology turned out to be up to the task. And so the quest for death rays led to the invention of radar, which played a crucial role in protecting Britain from bombers and rockets by detecting their presence and targeting them for gunneries.

Still, death ray inventors didn’t go away, the press kept reporting their claims, and a brief panic ensued after Tesla’s death in 1943. His talk of death rays in life raised concerns that he might have possessed sensitive documents. Federal agents hauled two truckloads of papers from the inventor’s residence, and called in a Massachusetts Institute of Technology engineering professor, John G. Trump—uncle to none other than sitting president Donald J. Trump and an expert on high-voltage equipment—to comb Tesla’s writings for death ray designs. After two days burrowing through Tesla’s notes, professor Trump concluded there was nothing to worry about.

“It is my considered opinion that there exist among Dr. Tesla’s papers and possessions no scientific notes, descriptions of hitherto unrevealed methods or devices, or actual apparatus which could be of significant value to this country or which would constitute a hazard in unfriendly hands,” wrote Trump, signing his letter as a technical aide to the government’s wartime National Defense Research Committee, and attaching a list of Tesla projects.

Trump was well aware that his comments about Tesla might seem harsh, so he closed by saying, “It should be no discredit to this distinguished engineer and scientist whose solid contributions to the electrical art were made at the beginning of the present century to report that his thoughts and efforts during the past fifteen years were primarily of a speculative, philosophical, and somewhat

promotional character.” That generosity reflects a colleague’s memory of Trump as “remarkably even-tempered, with kindness and consideration to all, never threatening or arrogant in manner.”

Trump did find that Tesla had tried to peddle the “death beams” of tiny particles at his 1934 birthday party. “Such beams would constitute a death ray capable of the protection of Great Britain from air attack,” Tesla had written British military officials who politely declined, and Trump agreed the plan wasn’t workable.

Beam weapons of all sorts became standard for science fiction thanks to the death ray craze, but by the early 1940s major military powers still preferred old-fashioned guns for shooting down enemy aircraft tracked by radar. The Japanese military did try to develop powerful microwave tubes for use as death rays, and managed to kill rabbits up to 30 meters from a tube emitting 200 to 300 kilowatts hooked up to a giant 10-meter focusing antenna. That’s a few hundred times the power of a modern microwave oven, but the lethal distance was only a third of the British Air Ministry minimum for killing a sheep.

Today, even our most advanced lasers and other directed-energy weapons have important limitations. Don’t be fooled by videos showing high-powered laser beams slicing sheet metal like butter. That beam is focused across a matter of inches so it can be concentrated on a tiny spot. Laser weapons are hundreds of meters or more from targets that may not be stationary, so the beam can’t be focused that tightly onto a spot. And far from achieving instantaneous obliteration, modern laser weapons are best at heating a thin-skinned fuel tank until the pressure blows out the softened metal, or heating an explosive to the detonation point. They can hit their target at the speed of light, but the beam has to dwell for quite a while to deliver a lethal dose of energy, like heating a teakettle of water on an electric stove.

Nonetheless, the Platonic ideal of a death ray–like laser retains the same magical appeal it generated a century ago. Defense Advanced Research Projects Agency Director Arati Prabhakar saw this laser enthusiasm among military officers during her tenure from 2012 to 2017 and told me that she found it rather ironic after the troubled history of laser weapons. “Most new technologies are viewed with suspicion and hostility by most military users,” she said. Lasers are the rare counterexample: “The enthusiasm of users has for decades outstripped the capability of the technology. The laser is such a powerfully exciting notion that their desire exceeds the capability of the technology. In the area of laser weapons, I spent a lot of time trying to reduce their expectations that lasers would make practical weapons.” Prabhakar acknowledged that lasers have completely changed military capabilities in other areas, citing laser range-finding and target designation, laser radars and sensing, and communications. But so far laser weapons have not. In the future, she says, “I think laser weapons may be a terrific solution for some very specific applications of enormous value. But there will not be a general-purpose laser weapon.” Death rays may always belong to the realm of fantasy.

Book cover for Lasers, Death Rays, and the Long, Strange Quest for the Ultimate Weapon.
Prometheus Books

Future Tense is a partnership of Slate, New America, and Arizona State University that examines emerging technologies, public policy, and society.