by Bob Berman
It took years to figure out what they were. Rutherford first assumed they were alpha particles that somehow had a much higher speed and that this was why they could penetrate dense materials such as metal. But while alpha particles were slow to deflect in a magnetic field, gamma rays would not deflect in any way. That was an important clue that they might be a form of light and not a particle at all. Finally, in 1914, Rutherford was able to bounce them off crystal faces and measure their wavelength. Bingo: gamma waves, the size of atoms, were so incredibly tiny and had frequencies so incredibly fast—more than ten million trillion per second—that they had more energy than even X-rays.
Here was the most powerful form of light ever discovered—a distinction gamma rays retain today. The power of gamma rays (also known as gamma radiation) is so great that it rips apart almost everything it touches. It is the most hazardous form of invisible light.
Alone among the various kinds of invisible light, gamma rays do not have a cut-and-dried wavelength. At one time they were categorized as waves with a shorter length and higher frequency than X-rays. Astronomers still use that as a hard-and-fast definition, no matter where the rays come from or how they are created. But some physicists now categorize gamma rays according to their origin alone. Gamma rays are usually born not as a result of electrons changing their positions, the way all other light is created, but from an atom’s nucleus as it emits energy when in an excited state (when it’s undergoing fission) or when it suddenly changes shape. Such nuclear transition occurs in a trillionth of a second, making gamma-ray production an extremely short-lived affair. A common modern definition holds that if rays emanate from an atom’s nucleus, they are gamma rays, period. If they originate from the motion of electrons, then they are some other variety of light. This controversial distinction has allowed some overlap between the frequencies we call gamma rays and those we call X-rays.
The bulk of the universe’s gamma rays are created by unimaginably violent events that take place far from our world, such as the annihilation of antimatter (matter with all its electrical charges reversed) when it strikes regular matter. Or supernova explosions. Or collapsing supermassive black holes.
Among the most exotic of these events are the gamma-ray bursts, discovered in the 1990s. Somewhere in the sky, beyond our own Milky Way galaxy, an average of once a day, a long (meaning ten-to-fifty-second) stream of gamma rays emanates from a single spot in the heavens. This is now believed to be the result of distant collapsing supermassive black holes, each emitting more energy per second than the sun gives off in its entire lifetime.*
A bizarre gamma-ray discovery in 2010 continues to cause much consternation. In November of that year, astronomers using NASA’s Fermi Gamma-ray Space Telescope, launched in 2008, announced something truly astonishing. Emanating from the center of our Milky Way galaxy are two bubbles made solely of gamma rays.
This would have been strange enough if the bubbles, expanding at 2.2 million miles an hour, were concentric—a bubble within a bubble—and were both centered at our galaxy’s core. But no. The two enormous spheres each hover in seemingly empty space above and below the black hole in the Milky Way’s nucleus. They are tangential to each other, touching at the galactic center to form a squat hourglass shape. The entire structure looks like the number 8.
An edge-on view of our Milky Way galaxy, showing the enormous, mysterious, ultrapowerful gamma-ray bubbles discovered in 2010. (NASA)
Stars do not emit gamma rays. This is why that dense gamma-ray swarm at our own galaxy’s center is so puzzling. It’s the unmistakable sign of extreme violence. And yet these days the Milky Way’s core is about as energetic as a steamy July lunchtime in New Orleans.
The bubbles are sharp-edged, well defined, and enormous. The top and bottom of the figure 8 extends from twenty-five thousand light-years north of the galactic plane to the same distance beneath it. From our earth’s sideways viewpoint, twenty-five thousand light-years from the center, the hourglass stands a whopping forty-five degrees above and below the galactic core in Sagittarius. It takes up half our southern sky.
Theorists need to explain more than just what could have produced this kind of extreme energy, which is equivalent to one hundred thousand exploding supernovae. They must also explain the off-center nature of the bubbles, because each seemingly surrounds nothingness.
Imagine a small expanding bubble inside a larger expanding one, both of them centered on the giant black hole at the center of our galaxy. We’d assume that some violent event in the past caused both bubbles to form—especially since both are composed of highly energetic gamma rays. But that’s not what we see. Instead we observe two separate bubbles, one atop the other, as if they were drifting and got stuck when they made contact. This place of bubble contact is the center of our galaxy, where the supermassive black hole floats. Yet the centers of both bubbles are high above and far below the galaxy’s center, in a region where we detect nothing at all. How strange it is!
Jon Morse, former director of astrophysics at NASA headquarters, summed up the discovery at a press conference: “It shows, once again, that the universe is full of surprises.” This gargantuan hourglass, called the Fermi Bubbles in honor of the orbiting gamma-ray telescope that found them, is now regarded as an entirely new type of astronomical object.
In trying to come up with some explanation for our galaxy blowing gamma-ray bubbles at temperatures of seven million degrees Fahrenheit, many astrophysicists express a gratifying unanimity: they say, “We have no idea.” Others, starting perforce from square one, have posited a couple of vague possible causes. The first is that, perhaps a few million years ago, a burst of star formation at the galactic center created numerous massive stars, all with high-speed winds consisting of high-energy particles. Since this alone could not begin to explain the superhigh energy within the bubbles, that theory further imagines that many of these stars blew up into supernovae simultaneously.
Don’t like that one? Neither do I. So let’s go to possible explanation number 2, which is that the four-million-solar-mass black hole at our galaxy’s center had a brief feasting frenzy when it captured particles shed by stars that once lurked at our galaxy’s core. This captured material was accelerated at its accretion disk, where material remains temporarily visible before falling in to the innermost zone, from which nothing can escape. Then, perhaps, that black hole could have developed something it does not presently have: twin jets of outrushing material. We see such blue jets exploding from the supermassive black holes in a few other galaxies. These jets could have possibly deposited energetic material above and below the galactic plane, although how bubbles then emanated from those positions is anyone’s guess.
The answer could be even stranger. Might these be long-sought signs of dark matter, the hypothesized material that possesses a gravitational pull and yet remains utterly invisible? Could this be what’s making our galaxy spin as if it were a solid vinyl record and causes other galaxies to behave oddly, too? Could dark matter be meeting its opposite entity (whatever that is) in total annihilation, the way matter and antimatter do? Maybe. More likely, though, is that the double bubble is something else entirely, some new phenomenon that will actually get in the way of the dark-matter hunt.
As Fermi research team leader Douglas Finkbeiner put it in an interview, “This just confuses everything.”
Fortunately, few gamma rays reach us here at the earth’s surface. An orbiting gamma-ray telescope, when pointed downward toward the ground, revealed that only five hundred brief flashes of gamma rays appear on earth each day, mostly from intense lightning storms.
Gamma rays are briefly emitted in the explosion of atomic and hydrogen bombs. But in terms of practical use, the fact that they easily destroy life—even insects, which are generally highly radiation resistant—has led the food industry to push for food irradiation as a way of preventing the sprouting of vegetables and fruits, thus preserving their flavor. The process is already widely used to sterilize sp
ices. In practice, this means that rolling shelves containing these products are exposed to high-intensity gamma rays, then rolled away as though they were on an amusement park ride. This kills all insects and pathogens.
Those in the natural food movement are not happy about food irradiation. They maintain that all foods contain a scientifically undetectable “life force” (called prana in India) that is destroyed by the process. Irradiated fruit, according to this view, may still contain its original quantifiable vitamins, and it may look the same as other fruit, but its cells and vitality have been destroyed by the gamma rays so that it lacks any “spark of life.”
Radium, used as a source of gamma rays, has also been employed to treat eczema and other skin rashes and to remove benign skin tumors and moles. Such radiation treatments were administered for almost forty years starting in the 1920s. They were also used to treat enlarged thyroid glands, inflamed tonsils and adenoids, asthma, whooping cough, and even a mother’s lactation problems after birth. These days, the one remaining acceptable medical use for focused gamma-ray beams is the destruction of tumors, mostly as a form of palliation.
Now you have heard the stories of how various forms of invisible light were discovered. The discoveries spanned nearly a century: the first invisible light was detected by the self-taught astronomer William Herschel in 1800; the most recent was identified by schoolteacher Paul Villard in 1900.
Throughout history, new elements and compounds have been found and their properties analyzed and exploited. But we have now seen that over the course of one curious century, a coterie of singular men—and one woman—made a series of discoveries that were truly bizarre. The sun, along with seemingly ordinary metallic-looking elements, sends out invisible rays, or in some cases tiny invisible bullets. These ghosts race through the air and affect other objects. They can even influence living beings. It was as if the scientists had discovered phantoms among us. As the technology needed to produce these invisible energies and use them in various products and applications became available, we soon reached a situation in which they fill all the spaces on our planet and fly through our bodies nonstop.
How do these phantoms affect our lives and our health as they provide their almost magical conveniences? We need to find out, since one kind of invisible light in particular lies at the center of our lives.
CHAPTER 18
Cell-Phone Radiation
We can’t say that no one saw the cell-phone revolution coming. In 1959, nearly a decade before his 2001: A Space Odyssey came out, science visionary Arthur C. Clarke wrote an essay describing a “personal transceiver, so small and compact that every man carries one.” He foresaw a time when “we will be able to call a person anywhere on earth merely by dialing a number.” The device would even contain some sort of global positioning system so that “no one need ever again be lost.” In a later book, Profiles of the Future, he predicted such telephones being available by the mid-1980s. (Yes, he was off by a decade. Clarke usually nailed the specifics but messed up on the timing. He envisioned humans venturing to Jupiter by the year 2005.)
We’ve come a long way from those huge brick-size satellite phones that were introduced in the 1990s to our present time, when virtually everyone has a personal phone in his or her pocket. Movies from the 1990s still show people waiting in line to use pay phones at the airport. These days, for a mere $150, residents of villages in South India that are still entirely off the grid can purchase siding-mounted exterior solar panels that let them charge their cell phones.
We have microwaves to thank for that progress. They’re the medium that makes cell phones work. And unlike Percy Spencer’s microwave ovens, the new devices are not the technological brainchild of any one person. The idea of cordless telephony has been around for nearly a century—some primitive systems were installed in European trains even before World War II. After that came “radiophones,” which often took up an entire attaché case and ultimately got as small as a milk carton, though they still didn’t allow the user to roam from one area to another.
The concept of a cellular network within which signals could transfer from one tower to another was developed in the 1960s through pioneering work by Bell Labs engineers Richard H. Frenkiel, Joel S. Engel, and Philip T. Porter, particularly the latter, when they suggested that cell towers use the now-familiar directional antennas, which would minimize interference and allow the reuse of specific microwave frequencies. Porter also was the first to suggest the dial-then-send calling method, which was ultimately adopted and which prevents wasted “on-air” channel usage.
In the 1970s, Bell Labs engineer Amos Joel invented a three-sided trunk circuit to aid in the call-handoff process from one cell to another, but switching improvements—meaning methods of sending and receiving calls—during the next decade leaped over even this idea and went directly from circuit switching to packet switching, in which entire chunks of data seamlessly change their transmission points. This is not the place for the almost magical story of technology’s evolution from the early 1G cell phones of the 1990s to the 2G, 3G, 4G, and 5G phones of later years, each making great leaps in data-carrying capabilities and bit rates to the point where intensive data-streaming capacity is now routinely expected on one’s smartphone. Instead we are here concerned about the invisible rays that make such streaming possible and what they may do to our bodies in the process.
We must also note that microwave signals originate not just from towers but also from satellites in high orbit, at 11,300 miles. The combined radio-spectrum environment from, among other things, the two dozen American GPS satellites now in space, new Chinese, European, and Russian satellite systems, and Iridium satellites, which provide satellite phone service, ensures that our homes and bodies are never devoid of electromagnetic radio waves. But if we’re near a cell tower, or in a Wi-Fi hot spot, we’re positively awash in them.
Visualizing microwaves isn’t easy. Sizewise, picture each ray as a curled-up caterpillar, with its back raised and its front and back ends lower down. The largest microwaves look more like garter snakes, a foot in length, again with the midsection raised in a curve. Each curved caterpillar vanishes, then a new one appears in the same spot a trillion times a second. That’s a million million. It’s fourteen thousand times faster than individual frames appear in modern movies.
Should we be concerned? Some people certainly do worry. You can read the anxiety in local newspapers, where letters to the editor express fear about microwaves from cell towers, Wi-Fi, and even cell phones themselves and urge that Wi-Fi be banned in schools. Authorities sometimes respond to this pressure: in Woodstock, New York, in 2015, the school board placed a temporary restriction on school microwave Wi-Fi installations pending further investigation.
The issue of whether cell phone radiation is putting us in danger has generated much press, some thoughtful, some paranoid. An example of the latter is the widespread belief, expressed all over the Web, that corporations involved in the cell-phone industry (including manufacturers, electronics and software companies, and the carriers themselves), as well as government regulatory agencies and even large mainstream health organizations such as the American Cancer Society and the Mayo Clinic, are actively conspiring to suppress microwave hazards of which they are supposedly well aware.
Some of the fears are based on a report issued in 2011 by the World Health Organization’s International Agency for Research on Cancer (IARC). The agency had gathered in Lyon, France, to discuss scientific studies surrounding the question of whether there’s a relationship between radio-frequency-modulated electromagnetic fields (RF-EMF) and cancer. After intense deliberations, and to the great surprise of the world at large, experts decided to classify RF-EMF waves emitted by cell phones, cell towers, and Wi-Fi networks as category 2B, indicating a “possible human carcinogen.”
On the other hand, as a New York Times article pointed out in 2016, there have been many studies conducted on the issue, including the Million Women Study, in Britain, a
Danish study of more than 350,000 cell-phone users, and studies examining the effects of radio waves in animals and cells growing in petri dishes. Those studies indicated that there is still “no convincing evidence of any link between cellphone use and cancer or any other disease. Also, the incidence of brain cancer in the United States has remained steady since 1992, despite the stark increase in cellphone use.”
Between the alarming conspiracy theories, the “possible human carcinogen” verdict, and reassuring reports like the one in the Times, it’s hard to know what to believe, and that in itself can cause anxiety, because we certainly need to know. More than a billion people use cell phones daily. Are our phones putting us in danger or not?
The short answer is probably not, but it’s still better to take certain precautions.
First of all, the microwave and radio bands consist entirely of nonionizing radiations. They simply don’t have the energy to knock electrons out of their orbits, which means they can’t cause changes on an atomic level. So even with prolonged exposure to microwaves or radio waves, there’s no danger of gene mutations or chromosome damage. And presumably there’s no possibility of such rays being carcinogenic.
Indeed, microwaves lie not merely outside the ionizing part of the electromagnetic spectrum but also far from it. Microwaves are less energetic than infrared radiation, which in turn is less energetic than visible light. And nobody can be harmed by, say, red mood lighting, even if it’s bright.
Is it okay to warm up your teenager’s brain? Regardless of whether microwaves can cause cancer (we’ll get to that in a second), we know that they do make atoms jiggle faster—another way of saying they heat tissue. One study showed a measurably increased blood flow on the side of the head where a cell phone was held. The effect was undeniable. But was it deleterious? Might it simply mean that a certain part of the brain had become actively engaged? One might point out that drinking a bowl of soup or enjoying a cup of tea will heat far more tissue, and to a much greater degree, than talking on a cell phone will, yet we don’t worry about the potential health risks of frequent tea drinking. Moreover, taking a single hot shower heats far more body tissue in one shot than using your cell phone nonstop for a month. So this “heating tissue” business is a good example of a real effect caused by radio-frequency radiation that sounds scary but in all probability is inconsequential.