Zapped

by Bob Berman

  Near the end of that century, Guglielmo Marconi and Nikola Tesla both attempted radio communication with Mars. By then scientists realized that visible light was an inadequate medium for sending messages between worlds. Radio signals were much more logical. When Mars came unusually close to Earth, from August 21 to 23, 1924, the notion of a National Radio Silence Day gained so much support that—at least in some areas—total radio silence was maintained for the first five minutes of every hour for thirty-six hours while a powerful dirigible-borne radio receiver from the United States Naval Observatory listened in vain for any signals from the Red Planet.

  By the 1950s, intelligent ET life in our own solar system no longer seemed likely, and our attention eventually turned to the many planets believed to orbit some of the four hundred billion stars of our Milky Way galaxy. The issue, then as now, was: how many of these distant suns have planets—and how many of those can be expected to harbor intelligent life?

  The answer to the first question only arrived at the beginning of this century. Two separate methods of hunting for exoplanets (planets that orbit a star outside our solar system) have already revealed thousands of them. It is now obvious that in our own galaxy alone there must be at least one billion earthlike worlds. That definition applies to planets of roughly our mass and temperature that orbit their stars at just the right distance to allow liquid water to exist on their surfaces.

  But how many of those billion planets are home to intelligent life? Astronomers tend to be optimistic. After all, they’ve detected amino acids, the building blocks of life, in many nebulae. It’s no longer much of a stretch to believe in panspermia—the theory that life’s precursors (if not actual simple microscopic forms of life itself) may lie in protected cracks and crevices of meteoroids roaming the vast hallways of interstellar space and plant their seeds during collisions with planets. If this is so, life should be plentiful. Only a small minority of astronomers take the opposite viewpoint, which is that life’s genesis is an extremely rare phenomenon and that essentially Earth is the site of a miracle.

  If we’d like to get in touch with any of these purported aliens, there are two methods, which essentially boil down to speaking versus listening. The former strategy means sending signals into space announcing our existence and position, then waiting to see if anyone replies. This has already been done to a small degree. In 1974 a three-minute message was broadcast using the giant Arecibo radio telescope in Puerto Rico, aimed at the rich globular star cluster M13, announcing our position in space. Given the light-speed travel time of those radio waves, the message will arrive at the one million stars of that cluster twenty-five thousand years from now. If any aliens there respond promptly, we’d expect to get their “Hi! Yes, we’re good. How are you?” sometime around the year 52000.

  In some circles, the idea of sending active messages into the cosmos has generated alarm. For example, the noted physicist Stephen Hawking warns that in our own earthly experience, whenever a civilization has let itself be discovered by a more technologically advanced culture, the results have rarely been favorable for the former.

  Just as it’s not a good idea to go around shouting in the jungle if you don’t know what’s around you, perhaps we should not assume that all technologically advanced extraterrestrials would have a benign attitude toward us. Says Hawking, “It would be wiser for us to lay low.” Not surprisingly, many scientists regard this stance as unduly paranoid.

  A less controversial way to search for extraterrestrials is to use our radio antennas to listen for either deliberate or accidental transmissions. After all, we earthlings have been broadcasting radio and television signals since the 1920s. It’s nearly a cliché to say that the I Love Lucy TV show is still zooming outward and has already reached a distance of sixty light-years from our planet. Its signal has reached hundreds of nearby stars and presumably a similar number of exoplanets. Not popularly appreciated, however, is that these signals are very weak. Aliens equipped with our own current best radio telescope technology would be unable to detect our presence from these commercial transmissions, even if they lived on a planet orbiting the very nearest star. But what if they were far more advanced than we are? What if they could both listen and broadcast at an extraordinarily sensitive level?

  Maybe alien signals are mere incidental transmissions just like ours, since we certainly did not broadcast Hawaii Five-0 and The Beverly Hillbillies so that they could be enjoyed in other worlds. Moreover, our radio and television towers transmit sideways, with the goal of reaching audiences stretching horizontally into the distance. Our commercial broadcasts are never aimed upward through the thinnest part of the atmosphere, toward space. Nor are they intended to be widely dispersed; they’re preferentially beamed toward population centers. Nor do they start off with interplanetary-level power.

  But the situation would be different if aliens were deliberately sending signals in the hope of being discovered. Starting in the 1960s, many listening projects have been funded with the goal of detecting exactly such alien transmissions.

  The first question is: what should we listen for? Of course we’re looking to detect invisible light. But at what wavelength and frequency? Essentially, what’s their phone number?

  The Crab Nebula sends out energy from almost the entire electromagnetic spectrum. If extraterrestrials are deliberately transmitting “hello” signals, which frequency would they choose for their broadcasts? (NASA)

  Realistically, we cannot listen to frequencies lower than one gigahertz, meaning the low microwave and long radio-wave part of the spectrum. Any lower than that, and there’s simply too much noisy competition and interference with our own earthly transmissions. That limits us—a position analogous to only looking for lost keys under a streetlight, as one noted ET investigator put it to me. But even excluding frequencies lower than one gigahertz, that still leaves us the vast majority of the electromagnetic spectrum.

  We assume that extraterrestrials would send radio waves, especially because (unlike visible light) they can be easily broadcast in all directions at once instead of focused in a single direction. But ETs might beam in the infrared section of the spectrum because such transmissions could be more concentrated. Indeed, some people have even suggested that the supermysterious gamma-ray bursts that pop out in the sky around once a day and usually last for just a few seconds might be concentrated high-power streams of artificially broadcast information from truly distant aliens in other galaxies.

  In 2016, I spoke with Seth Shostak, the famed director of the SETI Institute, which has been conducting its search for extraterrestrial intelligence for decades.

  “We get about four hundred letters a day,” he said with a sigh, “mostly from people with ideas about what frequencies we should be listening to. For example, some think that any alien intelligence would deliberately choose the numbers in pi, knowing that all smart life forms would recognize it as the universal figure that expresses the relationship between every circle’s circumference to its diameter. In other words, we should tweak our radio telescopes to try to detect 3.141592 gigahertz.”

  Others suggest some multiple of pi or things like pi times the 1,420-mHz frequency signature of hydrogen. In other words, asks Shostak rhetorically, “What would ET use as a hailing channel?” The problem with the electromagnetic spectrum is that the number of frequencies of invisible light are essentially limitless, while we keep listening to one or another very focused band.

  SETI’s ongoing efforts are the most famous, but they do not represent the first time we’ve hunted for invisible rays from extraterrestrials. In 1960, astronomer Frank Drake, who would go on to become a professor at Cornell University, used the eighty-five-foot radio telescope at the National Radio Astronomy Observatory in Green Bank, West Virginia, to try to detect messages from any unknown planets orbiting the nearby stars Epsilon Eridani and Tau Ceti, which are solar analogues and therefore not too fiercely hot. Called Project Ozma, the program was named after Princess Ozma, rul
er of the fictional land of Oz, which helped the project garner much mainstream media attention. Drake “listened” at the 1.420 gigahertz frequency, where hydrogen emits its famous twenty-one-centimeter-wavelength emission hiss—a logical place on the spectrum and a place that erudite aliens might know would be the natural focus for intelligent life. But his efforts produced no results.

  In 1971, NASA authorized funding for a SETI study, and in the 1980s a project named Sentinel used Harvard’s eighty-five-foot-diameter radio telescope hooked up to a spectrum analyzer that permitted listening to 131,000 frequencies at the same time.

  By the mid-1990s, a new search, called BETA (Billion-Channel Extraterrestrial Assay), had the ability to receive 250 million channels simultaneously. Along with follow-up projects, the search continued until a near-hurricane-level storm blew over and destroyed the radio telescope in 1999.

  Further listening for invisible light signals has made use of ever-improving technology, including spectrum analyzers capable of detecting fifteen million different frequencies simultaneously. These projects, some privately funded, some administered by universities or NASA, with names like MOP (Microwave Observing Project), SERENDIP (Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations), Project Phoenix, and Breakthrough Listen, are ongoing. And although hundreds of millions of potential technological (i.e., nonnatural) signals have been detected, all have thus far been attributed to noise and earthly satellites, or they have vanished too quickly to be properly analyzed.

  The Allen Telescope Array, which the SETI Institute uses in its hunt for extraterrestrial life. (Seth Shostak)

  In addition to the idea that an extraterrestrial intelligence might be sending us deliberate signals is the notion of “incidental” signatures from advanced technologies or even from something as simple as the infrared heat from a planet’s city lights and engine exhausts pulsing on and off as that world rotates.

  As of 2016, the number of stars we’ve looked at carefully, meaning those we’ve monitored thoroughly on lots of frequencies, is in the low thousands. So far, like Pavlov’s dogs, we’ve been patiently salivating but haven’t yet received a single biscuit.

  It’s possible that we’re wildly wrong about the likelihood of intelligent life out there. In the 1950s, the famed Italian physicist Enrico Fermi told his colleagues that if advanced civilizations are common in our galaxy, they should be detectable. But if that’s true, he asked, “Where is everybody?” This Great Silence, as some are now calling it, may suggest that advanced extraterrestrial life may be much rarer than we supposed. Such pessimism isn’t far-fetched. Life originating randomly from chemical combinations requires astoundingly rare sequences of events, which is why Fred Hoyle, who coined the term big bang, characterized the accidental genesis of life as akin to a tornado sweeping through a junkyard and assembling a working jumbo jet.

  Another explanation might be that others’ intelligence is not at all like ours. Just because we like to communicate via microwaves and radio waves doesn’t mean that others do. And just because we’re drawn to the notion of strapping ourselves inside a rocket and blasting into the hostile emptiness of space doesn’t mean that other intelligences find such activity in any way appealing. Perhaps they have sufficient peace of mind to stay put.

  What if ETs can communicate perfectly well among themselves without using waves of energy? Indeed, right here on earth, the most intelligent beings besides ourselves—dolphins—show not the slightest desire to hurl themselves outside the seas and beyond the planet. Nor do they show a desire to build electronic devices. What if they’re closer to the norm for ET intelligence than we are? What if all our listening to millions of frequencies of invisible light is a futility born of our own anthropocentrism?

  There’s no way to know. But we’re not going to stop.

  We’ll keep trying new phone numbers until someone picks up the receiver.

  CHAPTER 26

  Does Light Have a Bright Future?

  Two hundred years after William Herschel stumbled upon the invisible spectrum, there’s no sign that the flood of invisible light will ever grow less intense. On the contrary, even more unseen energies will be pumped through our homes in the coming years. Might these energies displace the visible wavelengths? Might society heed environmentalists’ calls to cut down on “waste lighting” and light pollution to preserve the glories of the natural night sky, all while ramping up the intensity of microwaves, radio waves, and other invisible electromagnetic frequencies?

  Already plans are afoot to use solar-powered drones to beam continuous widespread Wi-Fi signals over large areas so that “hot spots” are no longer spots but rather the norm everywhere. In short, you’d be able to use your smartphones and their apps even if you were hiking in a national park.

  Meantime, as SiriusXM satellite radio has demonstrated, satellites can and do beam microwaves and radio waves in blanket coverage that is blocked only by steep canyons and rock formations. The overall effect on our health? Probably somewhere between zero and negligible, although some say that “probably” isn’t enough assurance if you’re exposing absolutely everyone, including young children, to body-penetrating energy waves.

  Meanwhile, the use of hard, ionizing sections of the electromagnetic spectrum—we’re talking X-rays—continues to increase with the still-growing global popularity of CT scans. Articles in medical journals published since 2014 estimate that as many as 2 percent of all cancers are caused by medical X-rays, mostly from CT scans. Put another way, a single whole-body CT scan probably increases your cancer-death risk by one chance in two thousand. Happily, the awareness of this huge modern source of ionizing radiation is making many physicians step back and question whether CT scans are really necessary or whether simple X-rays may suffice in many situations. The awareness of the problem has arrived: we are now in stage 2—which is acting on it.

  Cell phones are another story. As their use goes from commonplace to ubiquitous, we know that virtually everyone is now exposed to microwaves. Those who hold their phones flush against their heads get the highest exposure by far. Those who simply text, or use headphones or earbuds, receive very little of this radiation. Fortunately, the phones themselves have been reducing their broadcast-output signal strength. As of 2016, the amount of microwaves in the air from cell phones is only around half what it was just fourteen years earlier. Ongoing studies examine animal exposure over long durations. As noted earlier, studies on humans have been mostly reassuring, but until certainty is reached, it might be wise to use the speakerphone feature.

  When we speak of cosmic rays, we’re talking about invisible particles rather than rays, but nonetheless it is interesting that the strength and frequency of the sun’s activity—its flares, coronal mass ejections, and sunspots, all of which emit a steady “wind” of charged particles—have been declining since the late 1990s. The sun’s current cycle, number 24, is the wimpiest in our lifetimes, and most solar researchers believe that the sun has entered an extended period of inactivity.

  At first this may seem reassuring to those who are wary of cosmic rays and their by-products, including potentially cell-damaging muons, two hundred of which penetrate our bodies every second. A quiet sun should mean fewer cosmic rays. However, it turns out that the real consequence is just the reverse.

  That’s because the most intense cosmic rays are not of solar origin but rather come from beyond the solar system; these are primarily the rays that affect animal life on earth. And most of these are deflected at the heliopause—the outer edge of the solar system—but mainly when the sun is active. In short, the sun’s current quietude has reduced the effectiveness of its barrier against interstellar invaders. The situation is allowing far more of those powerful cosmic rays to penetrate all the way to our planet’s atmosphere—and even to the ground. This is experienced most by those who live at high elevations, as in Colorado, and by those whose homes are remote from the equator, as in Alaska.

  As
for ultraviolet radiation, the sun’s quietness has also reduced UV intensity. Although each sunspot minimum (a quiet period in solar activity, which is predicted to occur again in 2022) reduces visible solar insolation—the brightness of the sun’s energy as it strikes our world—by only a single watt per square meter of the earth’s surface (compared to the sun’s brightness at its maximum), it also cuts the sun’s UV emissions by more than 10 percent.

  It is also true that the ozone hole at extreme southern latitudes continues to let more UV radiation bleed through than will be the case if and when that region of ozone depletion is patched. Still, as we’ve seen, UV radiation is less of a problem than was feared a few decades ago, at least in terms of melanoma genesis. The advice stands: don’t hide from the sun. Instead get as much sunlight as you can without burning.

  As for gamma rays, they will continue to be used for food irradiation—in the best-case scenario, irradiation will be limited to a small minority of foodstuffs, such as spices. Besides people who work at nuclear power plants and people with advanced cancer (for whom radiation is used as a palliative), no humans or animals are exposed to gamma rays.

  Infrared radiation continues to be used for garage-door openers, in heat lamps, in fire-detection equipment, in spy cameras, and in other products and gadgets. No harm to humans has ever been associated with this part of the spectrum. Possibly the most promising new IR technology involves restoring sight to the blind. One such product went on the market in 2016, and the company claims it will give totally blind people vision of at least 20/250, which would be sufficient to read the topmost line—that enormous E—on a standard Snellen chart.