by Bob Berman
As for your own safety when using a microwave, just check out the screening that seems to be part of the glass in the door. The size of the holes is no accident. They’re designed to be smaller than the microwaves, which, as you may recall, vary from around half an inch to one foot across. None can fit through the holes, and therefore not a single microwave can leave the oven to heat the gum you’re chewing as you stand there, impatiently waiting for the beeps. Bottom line: independent testing consistently shows that microwaves never escape from the oven. So yes, you can keep standing there, watching the hypnotic spinning of your frozen burrito.
Anyway, what on earth is better than a microwave when we want to salvage week-old frozen pizza slices or enjoy some quick popcorn? Indeed, on your next movie night, take a second to salute Percy Spencer with your butter-coated fingers. Spencer was eventually awarded an honorary doctorate from MIT—not bad for a guy who never completed sixth grade.
We’ve established that food cooked in microwaves is safe to eat, but still the sight of hot dogs sizzling in a microwave oven—of microwaves cooking flesh—can give one pause. If they can do that to store-bought wieners, what can they do to us? You could ask Siri on your cell phone, but then again, cell phones use radiation in the microwave spectrum. More than a billion people use cell phones every day. You probably have yours close at hand right now. What emissions is it sending your way, and what effect are they having on you?
Spencer would probably never have worried about it. After two marriages and three children, Spencer went to microwave heaven in 1970, at the age of seventy-six.
CHAPTER 13
The Man with the X-ray Vision
We probably utter the word X-ray far more than the words for other kinds of invisible light. We know about infrared light, but we usually refer to it as heat, as in our bathroom’s heat lamp. Ultraviolet light, too, is seldom referred to, and then only as something to avoid—for example, when we apply a UV blocker at the beach. But when it comes to Wilhelm Conrad Röntgen’s discovery, we ask for it by name: “My doctor sent me for an X-ray.” Maybe it has something to do with that nerdy X, a letter that has never lost its attraction for sci-fi lovers and gadget freaks.
Wilhelm Conrad Röntgen was born on March 27, 1845, in Lennep, Germany. His family was neither poor nor fabulously wealthy. His parents manufactured and sold cloth. When he was three years old, his family moved to the Netherlands, where he went to boarding school. Written accounts of his childhood reveal that Wilhelm had a deep love of nature and of trekking in the forest, a pastime he never abandoned. He was also handy, which is perhaps why at age seventeen he entered a technical school in the Dutch city of Utrecht. The oddest story of this period, though irrelevant to his later accomplishments, is that he was thrown out of that school for drawing a caricature of one of the teachers. In fact, although he’d been caught with that drawing in his hand, he’d kept his mouth shut and refused to rat on the actual artist. The culprit was the student at the desk next to his. The expulsion cost him; when he applied to Utrecht University, in 1865, to study physics, he was denied admission. But he wasn’t giving up. He learned that students could enter the polytechnic institute in Zurich if they could pass its tough entrance exam; he took it and breezed through it easily.
Röntgen thus began his studies of mechanical engineering, and in 1869 he earned his PhD at the University of Zurich. Five years later he was appointed as lecturer at the University of Strasbourg, and the following year he landed a job as professor in the agricultural academy at Hohenheim. In 1879 he accepted an invitation to become the chairman of the physics department at the University of Giessen, and—continuing his ascent up the academic ladder—accepted the same position in 1888 at the University of Würzburg. This was an important move, because his colleagues at that point included several others in our larger story, including radio-wave pioneer Heinrich Hertz as well as Hendrik Lorentz, who predicted the existence of the electron.
Röntgen met his future wife, Anna Bertha Ludwig, there, too, at a coffeehouse. A tall brunette and his senior by six years, she was the thirty-two-year-old daughter of the proprietor. They married the following year, 1872. Although they were unable to have children, in 1887 they adopted the six-year-old daughter of Anna’s brother.
Röntgen worked hard and, starting in 1870, had several papers published in popular areas of research at the time, including the thermal conductivity of crystals and the electrical properties of quartz. But it is the strange new rays to which his name came to be forever linked that interest us, and this is what held his curiosity and inspired his hand-built experiments in 1895. Working without an assistant, he pursued a major late-nineteenth-century enigma: the strange invisible energies that materialize when a high-voltage electric current is sent through tubes containing so little gas that what they hold is nearly a vacuum. He was probing those mysterious “cathode rays” before they were found to be electricity.
On the night of November 8, 1895, he noticed an odd thing. He’d wrapped the glass vacuum tube in thick black cardboard to block all light and placed a paper plate coated with a barium compound six feet away. When he shut off all the lights in the room, the paper plate glowed. Intrigued, he went further—blocking the glass tube with substances of various thicknesses to see which permitted these odd unseen rays to still make the distant barium glow.
For weeks he barely slept as he continued performing experiments with this strange new invisible emission that seemed to be reaching out from the glass tube and affecting objects many feet away. Then, on December 22, he decided to try something novel. He held up a photographic plate a few feet from the tube while the high-voltage current was turned on. Then he took his wife’s hand and held it motionless in front of the plate for several long seconds. As he developed the photograph, there appeared a ghostly image of the bones of her hand, including her wedding ring, with fainter gray impressions of the surrounding flesh.
When he excitedly showed her the picture, Anna screamed. A perfectly natural response, considering that until then, no one had ever seen the skeleton of a person who wasn’t long dead. “I am seeing my own death!” she exclaimed in horror. He reassured her that there was no danger. But her reaction may have rattled him. He became one of the first and only researchers to use a lead apron and other screening tools while in his lab to block these unseen rays from penetrating his body. And although he died twenty-eight years later of intestinal cancer, it’s widely believed to be a coincidence, because his cumulative exposure to X-rays is not thought to have been excessive enough to cause the illness.
The photograph of Anna’s bones and the ring on her finger proved that some new ray of invisible light was involved in creating the image. Previously discovered forms of invisible electromagnetism did not behave this way: they did not penetrate solid objects such as flesh and paper only to be stopped by denser materials such as bone. These new rays were obviously highly penetrating and did not reflect easily, as did other forms of light. Since their properties were mysterious, he assigned to them the classic mathematical expression of the unknown—the letter X—though most people wound up calling them Röntgen rays and continued to do so for many years to come. Röntgen published a paper about his findings on December 28, 1895, entitled “On a New Kind of Rays” (“Über eine neue Art von Strahlen”). The press soon got hold of it, and word spread quickly. It was reproduced in the US journal Science on February 14, 1896.
For years, the X in X-rays remained appropriate, as their true nature continued to be enigmatic. It took until after the turn of the century for Max von Laue, who won the Nobel Prize in 1914, to show that the way X-rays diffract or interfere with each other when encountering crystals proves that yes, they’re truly electromagnetic in nature, like all other forms of light. Moreover, they vibrate at astonishingly high frequencies—on the order of a million trillion waves per second. The distance between each of their waves is only a billionth of a meter, or 1/30,000,000 of an inch. In contrast with Hertz’s newfound radi
o waves, which can be as long as a mile from crest to crest, the idea of waves no larger than atoms seemed preposterous—one reason why their true properties stayed hidden for the next half century.
Super-packed-together, super-high-frequency X-rays have powers and abilities that put them worlds away from, say, familiar red sunset light. Indeed, they opened the door to technologies that still seem straight out of science fiction. But before we explore these, let’s close our story of their discoverer.
If the acclaim showered on Hertz for his radio-wave discovery seven years earlier was deafening, it was a mere whisper compared to Röntgen’s instant celebrity. The potential to use Röntgen rays in medical diagnosis was recognized immediately. Numerous honors were lavished upon him. In several cities, streets were quickly named after him, and he received an avalanche of honorary memberships in learned societies around the world.
In spite of all this, Röntgen remained more than merely modest. Though he realized how enormously lucrative it would have been to patent his rays, he refused to do so, preferring to let the world freely use his discovery. And when he won the Nobel Prize in Physics, in 1901—the first ever—he donated his prize money to his university.
In 1914, Röntgen intended to immigrate to the United States, having been offered prestigious teaching and head-of-department positions at Columbia and other universities. He bought steamship tickets for his family. The sudden outbreak of World War I put his plans on hold. It was a delay that, sadly, proved to be permanent. After the war, the runaway inflation then affecting the Weimar Republic virtually bankrupted Röntgen, though he managed to hang on to his modest summer house in Weilheim, in the foothills of the Bavarian Alps. To the end, he never lost his lifelong love of nature and only stopped his routine of trekking through the Alps when his intestinal cancer became too advanced. At the age of seventy-seven, four years after his beloved Anna passed away, he joined her.
CHAPTER 14
Röntgen Rays for Everyone
The ink on Wilhelm Röntgen’s paper announcing his discovery, published on December 28, 1895, had barely dried, and already it was causing a sensation around the world, one that would continue through the following year. By the end of 1896, scientists had created thirty-two distinct X-ray tube models. More than a thousand published scientific papers on the new rays appeared during that single year. In the midst of this X-ray mania, no one suspected that this marvel of science might have a dark side.
Some science luminaries did at first dismiss the discovery out of hand. Lord Kelvin, who had won international acclaim for successfully overseeing the laying of the first transatlantic telegraph cable, called X-rays a hoax and declared, very simply, that they did not exist. For a few weeks, many others in the sciences reacted with caution, too. In late January of 1896, the journal Science wrote with skepticism, “It is claimed that Dr. Röntgen has found the ultra violet rays from a Crookes vacuum tube penetrate wood and other organic substances, whereas metal, bones, etcetera are opaque to them.”
But all skepticism disappeared by February of 1896. Even before the start of spring, Scientific American predicted that Röntgen would be “immortalized for his discovery, and the year 1896 distinguished as the Röntgen Photography Year.”
Thomas Edison, America’s most celebrated inventor, wasted no time exploiting this new technology. It was still winter when he started building his own X-ray machine. In a letter, he told a friend that he wanted to perfect the X-ray technology “before others get their second wind.” A mere twelve weeks after Röntgen’s paper appeared, Edison had invented the fluoroscope, which, instead of taking a photograph, produced a sharp real-time moving X-ray image on a screen. Moreover, he announced, he would not patent this device but donate it freely to the world, as Röntgen had done with the X-rays it employed.
Following the strategy he used for his other vox-pop inventions, including the phonograph, Edison also created a version of the device—in this case, a portable fluoroscope—whose purpose was neither research nor diagnosis but rather entertainment. On May 4, in a New York City exposition hall, he unveiled the device and invited members of the audience to see their own bones on a glowing bluish screen. Crowds jostled to get close to the machine. Several hundred people at a time were allowed to file into the darkened room, taking turns, in pairs, putting their hands behind the screen. Demonstrating his showmanship, Edison arranged for a deep foghorn to sound each time the operator activated the device and ghostly images of the visitors’ bones materialized. The deafening blast heightened the sense of drama. The crowds went nuts.
By that first summer, newspapers were filled with speculations and claims about the supposed health-restoring power of these new rays. The stories found an eager, uncritical audience: various “invisible rays” had been touted for years for their purported ability to rejuvenate the body. Electricity in particular was widely used as a tonic, supposedly offering cures for every imaginable ailment. In the mid-nineteenth century, a typical visit to a doctor included “electrotherapy” (or at least a conversation about it). Practitioners—some actual physicians, but mostly charlatans—moistened the patients’ skin, attached electrodes to whatever site needed treatment, connected the cables to a powerful battery, and applied various amounts of “restorative” voltage. Treatment regimens were prescribed for menstruation problems, insomnia, anxiety, and a growing list of diseases and their symptoms. Depending on the complaint, the electrodes were placed in the rectum, the vagina, atop the base of the skull, on the uterus—pretty much anywhere. There were even “electrical baths” in which the patient experienced a whole-body tingling sensation delivered by wires suspended in warm electrified salt water. With electrotherapy then in vogue, it is small wonder that any freshly discovered rays would likewise be hailed as salutary—invisible spirits that can help us rather than phantoms that can scare us.
Quite suddenly, X-rays were all the rage. Articles about their powers appeared daily, many of them contradictory. X-rays could kill germs or they could restore friendly body essences. They could remove unwanted hair or stimulate hair growth. They could even restore sight to the blind.
This last claim had a strange etiology: many people claimed to be able to see X-rays that were aimed at their eyes. Today, few such vision-affecting claims are taken seriously—though nowadays it is of course unethical for any kind of X-ray beam to be aimed at a person’s eyes. Nonetheless it’s now generally acknowledged that humans can indeed perceive X-rays, at least sometimes, as a blue-gray glow. The mechanism by which we do this is unknown, and the whole issue is still bathed in mystery. The three most plausible theories posit that either (1) perception of X-rays results from the excitation of the retina’s rhodopsin molecules, (2) X-rays directly excite retinal nerve cells, or (3) the observer experiences some secondary form of visual stimulation, such as X-ray induction of phosphorescence within the eyeball.
The first X-ray photograph after Röntgen’s own was probably created a mere fourteen days after the discovery’s publication. That’s when Friedrich Otto Walkhoff took the first ever dental X-ray image, of his own teeth. He held a photographic glass plate in his mouth between his teeth and tongue and lay as still as possible on the floor for twenty-five minutes, with the high-voltage glass tube precisely aimed at his jaw.
Virtually no one called the new images of people’s bones X-rays. They were shadowgraphs, cathodographs, electric shadows, and, most commonly, Röntgen photographs. Whatever you called them, they seemed too good to be true. By March of 1896, reports were circulating among physicians that X-rays had been used to find a bullet in the brain of a twelve-year-old child and to photograph a broken hip joint. People began building and selling homemade “Crookes tubes” at a furious rate: purchasers scooped them up as if they were today’s latest iPhone model. The use of “Röntgen radiographs” (yet another early name for X-rays) skyrocketed. By the end of 1896 a Chicago electrical engineer named Wolfram C. Fuchs had performed more than 1,400 X-ray examinations, and doctors had star
ted routinely referring their patients to “Röntgen specialists,” who used primitive, often home-built machines that typically required an hour of nonstop exposure.
But for all their purported benefits, X-rays had some negative effects, too. It didn’t take long for these to become obvious, because few practitioners bothered using lead aprons on themselves or the parts of their patients that didn’t need to get zapped. Moreover, unfocused X-ray beams often penetrated walls, irradiating people in other rooms. Machine operators frequently tested their equipment by placing their hands in the beam. Many did this every single day. Wild overexposure was the norm. But while the world continued its celebration of the new invisible light, some in the medical profession were noticing odd, disturbing reports even during that first year. Most of those reports centered on skin blisters, which are now known to be a telltale sign that a person has absorbed a dose of at least 1,500 rads, a huge amount of radiation that greatly exceeds what most Hiroshima survivors endured in 1945. Writing in New York’s Medical Record, Dr. D. W. Gage, of McCook, Nebraska, also cited cases of hair loss, reddened skin, skin sloughing off, and lesions. “I wish to suggest that more be understood regarding the action of the x rays before the general practitioner adopts them in his daily work,” Gage warned.
That summer, at Vanderbilt University, a physician decided to experiment on himself before using X-rays to locate a bullet in a child who’d been accidentally shot. He placed the X-ray tube half an inch from his own head and turned on the tube for an hour. At first nothing seemed amiss. Yet three weeks later, all the hair in the directly exposed area fell out, creating a bald spot two inches in diameter.