by Bryan Walsh
Fermi’s antics irritated the military commanders overseeing the Manhattan Project, who worried that his joke—and it was mostly a joke—might spook the soldiers securing the Trinity site. But as Richard Rhodes writes in his magisterial history, The Making of the Atomic Bomb, “a new force was about to be loosed on the world; no one could be absolutely certain—Fermi’s point—of the outcome of its debut.”13
The LA-602 report was a footnote in the history of the Manhattan Project, but it holds a special place in existential risk studies. It marked the first time humans had tried to figure out in advance whether their actions could bring about the end of the world. “It’s the first technical assessment of an anthropogenic existential risk, rather than a religious one, or one related to a natural hazard,” said Jason Matheny, the former director of the Intelligence Advanced Research Projects Activity (IARPA), perhaps the closest entity the U.S. government has to a successor to the Manhattan Project. The debate over the existential dangers of biotechnology, the dueling visions about the threat from artificial intelligence, even this book—they can all be traced back to LA-602, a report that wasn’t even declassified until 1973.
As it turned out, the Trinity test demonstrated that for atomic weapons at least, it wasn’t what would happen if they went wrong that we should fear most. It’s what would happen when they went right.
With twenty minutes to go before ignition, Sam K. Allison of the University of Chicago began the world’s first countdown over a loudspeaker. As Allison reached the last few seconds, a local radio station began broadcasting on the same wavelength, overlaying Tchaikovsky’s Nutcracker Suite upon the falling numbers. Twenty miles away, observing the test site from Compania Hill, Edward Teller began making everyone nervous—or more nervous, at least—by offering to pass around suntan lotion he had brought.14 At 5:29:45 a.m., the Trinity bomb detonated.
From the parking lot Eckles and I walked a few hundred feet to Trinity Site itself. It was fenced in from the desert. There was bright yellow grass, surrounded by the greener brush that extends out to the Sierra Oscura. If I had a Geiger counter I would have detected the slightest uptick in radiation—another echo of the bomb15—though not anywhere near enough to cause harm. Near the center of the site is the actual and first Ground Zero, the spot where on July 16, 1945, a hundred-foot steel tower stood, topped by the Gadget. (The tower itself was called Zero; the ground at the foot of the tower was named Ground Zero, which is where the term originates.) Today Ground Zero is memorialized with a stone obelisk mined from nearby volcanic rock—black and brown stone born of fire, as Eckles told me, to represent the ultimate fire. A plaque states the facts of what happened that day in the simplest terms: Trinity Site—where the world’s first nuclear device was exploded on July 16, 1945.
Standing before the obelisk, I recalled that a few weeks after the Trinity test, Lieutenant General Groves had been driven out to the site on an observation trip. Victor Weisskopf, a nuclear physicist who had worked on the Manhattan Project, remembered Groves looking at the crater left by the first atomic test, and the general remarking: “Is that all?”16 I now understood what he meant.
Beyond the obelisk, though, I could see black-and-white historical photos arranged against the fence. Between portraits of Manhattan Project scientists and images of the Gadget itself was a frame-by-frame series of the milliseconds after the Trinity bomb exploded.
At 0.006 seconds there is a bubble of perfect light, as if the dawn itself had blossomed suddenly out of the desert ground. The heat of the blast is thousands of times hotter than the surface of the sun, and the light in that single moment was a dozen times brighter.17 At 0.025 seconds, the bubble head keeps rising, while a fringe of fire spreads across the ground. It will carve a crater half a mile across, and suck up hundreds of tons of sand into the blast interior. Later the silica in the sand will adhere to radioactive particles and rain back to the surface as something wholly new: bright green trinitite, also known as Alamogordo glass. For decades after, tourists will collect shards of trinitite as souvenirs from the site, even though removing it is technically illegal.
At 0.053 seconds, that perfect bubble begins to lose its clarity, becoming diffuse and unfocused, as if overwhelmed by its own energy, while the inferno at the surface expands, gouging out the earth below. At this point every living thing within a radius of a mile is dead, or will be soon. At .10 seconds, the blast looks like nothing less than a halo ringing the head of some Renaissance painting of Christ, as the exposure itself begins to degrade. The atomic heat has made the air glow luminous, as the force of the shock wave expands outward, shredding the matter in its path. Everything is ravaged, everything is burned. And at 15 seconds after detonation comes the familiar image of the mushroom cloud, what the art historian John O’Brian called the “logo of logos in the 20th century,”18 a symbol that would shadow humanity for decades to come. That mushroom cloud—like nothing seen on Earth before—is the result of the intense heat at the heart of the blast, causing the air to rise in a column, before it spreads out in a cap.19
Less than a minute after the explosion, Enrico Fermi stood up and released slips of paper into the air. He estimated from their deflection in the blast wave that the Trinity explosion had released the equivalent of 10,000 tons of TNT. Fermi was off, but his impromptu experiment proved far more accurate than the Manhattan Project’s conservative pretest estimates. Trinity’s destructive power was close to 21,000 tons of TNT. Isidor Isaac Rabi, a Manhattan Project physicist who’d come late to the test and took the last available bet in the pool, won with a guess of 18,000 tons.
Entire books can and have been filled with the testimonies of the men who were there at Trinity. There is the scientific reaction and the military one, the religious and the poetic. But of all the words spent in witness I prefer those of Rabi, who had filled the tense night before the Trinity test playing poker:
A new thing had been born; a new control; a new understanding of man, which man had acquired over nature.… Then, there was a chill, which was not the morning cold; it was a chill that came to one when one thought, as for instance when I thought of my wooden house in Cambridge, and my laboratory in New York, and of the millions of people living around there, and this power of nature which we had first understood it to be—well there it was.20
News of the successful Trinity test reached President Truman, who was touring a bombed-out Berlin on the way to the Allied conference in Potsdam, Germany. He wrote in his private diary that the atomic bomb “seems to be the most terrible thing ever discovered, but it can be made the most useful.”21
In one way Truman was wrong. The atomic bomb had not been “discovered,” in the sense of simply being found somewhere, but had been called into being by the decisions of politicians and generals and the hard work of thousands of scientists. But in another way Truman was more correct than he could know. Before the Manhattan Project was launched, before the decision to test and then use the atomic bomb, scientists who made pioneering discoveries in nuclear physics in the decades leading up to the war had been laying the groundwork for Trinity, without fully knowing what their work might lead to. Many dismissed an atomic bomb as impossible.
Not all, though. Leo Szilard was one of the few physicists who from the start knew that the likely outcome of the groundbreaking atomic research of the 1930s would be nuclear weapons. The Hungarian-born Szilard—who earned his PhD in Germany, which he fled following Adolf Hitler’s rise to power in 1933—drafted the famous letter sent by Albert Einstein to President Roosevelt in 1939 warning that nuclear bombs were possible and urging the United States to launch what would become the Manhattan Project. And it was Szilard who, in the months leading to the Trinity test, became the most prominent voice urging Washington not to use the bomb, should the test prove successful. His call went unheeded.
Three weeks after the test, the B-29 bomber Enola Gay took off from an air base on the Mariana Islands and flew toward Japan. A version of the Trinity device was nestled in its bombing b
ay. At 8:15 a.m. local time on August 6, at 31,000 feet over the southwestern Japanese city of Hiroshima, the Enola Gay released its payload. Robert Lewis, the copilot on the flight, later recorded the dissociation he felt as the bomb fell: “The bomb was now independent of the plane. It was a peculiar sensation. I had a feeling the bomb had a life of its own now that had nothing to do with us.”22
The bomb detonated 1,900 feet above the city. Within a millisecond, the heat was so intense that as far away as 2.3 miles from Ground Zero, the temperature of a person’s skin could be raised to 120 degrees.23 Within minutes, 9 out of 10 people inside a half-mile radius of Ground Zero were dead, their bodies burned away to black char. The suffering of those who survived defies description, though it remains seared in the memories of victims like Setsuko Thurlow, who was a thirteen-year-old girl in Hiroshima the morning the bomb was dropped. What she witnessed was still vivid in her mind seventy-two years later, when she co-accepted the Nobel Peace Prize for the International Campaign to Abolish Nuclear Weapons (ICAN). “When I remember Hiroshima,” Thurlow told the audience in Oslo, Norway, “the first image that comes to mind is my four-year-old nephew, Eiji—his little body transformed into an unrecognizable melted chunk of flesh. He kept begging for water in a faint voice until death released him from agony.”24
Some seventy thousand people likely died as a result of the initial blast, heat, and radiation, and thousands more would die from injury and radiation-induced cancer in the months and years that followed.25 As high as the numbers were, though, it was not the death toll alone that set Hiroshima apart. America’s incendiary bombings of Tokyo with conventional weapons in 1945 had killed even more people, but that had required the work of 300 planes dropping 8,000 bombs over the course of two nights.26 Hiroshima had needed but one plane, and one bomb, a bomb of unimaginably concentrated destruction.
After the atomic bombings, it was said to Leo Szilard that it was a tragedy for scientists that their discoveries were used for destruction. No, Szilard replied, it is not the tragedy of scientists. It is the tragedy of mankind.
Those words were prophetic, and they’ll rain over the rest of this book like Alamogordo glass. Scientists move civilization forward through their pursuit of knowledge, but Trinity demonstrated that their pursuit can inadvertently create the conditions for our own doom. Existential threats can be brought into the world not by those who wish to end it, but by those who hope to better it. Intentions don’t matter for the fate of the world—results do. As Richard Rhodes wrote of the Manhattan Project’s legacy: “The scientific method doesn’t filter for benevolence. Knowledge had consequences, not always intended, not always comfortable, not always welcome.”27
There were no pictures of Hiroshima at the Trinity site the day I visited. Like so much else at Trinity, its presence is felt through its absence, just as the site itself is a reminder of a threat we’d rather forget. “All those missiles and all those weapons are still out there, and we blithely go along in our everyday lives,” Jim Eckles told me, as we stood under the New Mexico sun. “Every minute of the day. It’s in the back of our minds, and maybe Trinity, it brings it forward just a little bit. Let’s meditate on that, that this is still a threat.”
Eckles looked at the emptiness that makes Trinity Trinity. “It doesn’t really change much for anybody, but at least there’s this reminder here.”
Once the destructive power of the nuclear bomb had been demonstrated at Hiroshima, and three days later at Nagasaki, other nations rushed to arm themselves with this terrible new weapon. The Soviet Union tested its first bomb in 1949, Great Britain in 1952, France in 1960, China in 1964. The thermonuclear or hydrogen bomb, hundreds of times more powerful than the fission device tested at Trinity, was developed by the United States in 1952. The Soviet Union followed with its own thermonuclear weapon the next year.
These new weapons of mass destruction were at first brandished with little care. Atomic bombs were tested—which at the time meant exploded above the ground—almost once a week on average during the 1950s and ’60s.28 Because the U.S. military in Europe was outnumbered by the Soviets by as much as ten-to-one during the initial stages of the Cold War, Washington was dependent on the threat of its nuclear arsenal to repel a conventional attack29—and was quick to threaten its use. President Dwight Eisenhower considered using nuclear weapons during the end stages of the Korean War in 1953, over the Taiwan crisis in 1958, and over a dispute with the Soviets about the fate of Berlin in 1959. President Lyndon Johnson was prepared to preemptively strike China to prevent the communist government in Beijing from developing its own nuclear arsenal. Eisenhower even signed an agreement delegating the authority to use nuclear arms to generals and admirals outside of Washington, in the event that the U.S. capital had been destroyed, and those generals and admirals in turn delegated that power down the chain of command until junior commanders aboard oceangoing warships had the power, on their own, to launch nuclear weapons in a crisis.30
Nuclear arms were initially considered another weapon—powerful, of course, but not necessarily special or civilization-threatening. There wasn’t yet a full understanding of what a global nuclear war would actually mean for the human beings living through it. This was the age of backyard fallout shelters, when Life magazine could run a cover in 1961 of a man in what the editors identified as a “civilian fallout suit,” cowering beneath the headline “How You Can Survive Fallout: 97 out of 100 people can be saved.”31 The Federal Civil Defense Administration (FCDA), created in 1951 by President Truman, pumped out a steady stream of dubious advice for surviving the unthinkable. That included “Bert the Turtle,” an animated character who showed children in song what to do in the event of a nuclear strike: “There was a turtle by the name of Bert and Bert the turtle was very alert; when danger threatened he never got hurt. He knew just what to do. He ducked! And covered!”32 The U.S. Postal Service printed 60 million change-of-address labels and sent them to regional offices, in case a nuclear war left tens of millions of American refugees who nonetheless wanted their magazines forwarded.33 At one point the Eisenhower administration had a plan to dig trenches alongside public highways so that if Americans were caught out in their cars during a nuclear strike, they could try to survive by abandoning their automobiles, lying down in the trenches, and covering themselves with dirt.34
Ducking and covering is actually good advice should you have the grave misfortune to be caught near a sudden nuclear strike. “If you’re talking about a kiloton-range weapon, there’s actually quite a lot you can do to change your odds of survival,” said Alex Wellerstein, a historian at the Stevens Institute of Technology who studies the history of nuclear weapons. “But if you’re talking about an exchange between nuclear powers with thousands of weapons, there isn’t much you can do.” The idea that 97 out of 100 Americans could survive a full-scale nuclear war through ducking and covering was plainly absurd. These plans for what came to be known as civil defense represented what the sociologist Lee Clarke has called “fantasy documents”—exercises that were done to give both the citizenry and the bureaucracy a sense of control, however fantastical, over the uncontrollable.35
But we shouldn’t be too quick to judge. Again and again we find that the biggest barrier to combating existential risks—including nuclear war—is a mental one, for the human mind rebels against the sheer scale of extinction.36 Homo sapiens evolved to live in small groups, and so we feel acutely the grief of small-scale loss, that of a friend or a relative or even a stranger. But there is no individualizing the deaths of billions of people, perhaps even our entire species. And so we choose to deny it.
Our empathy actually erodes as potential death tolls grow, thanks to a psychological process called scope neglect. Few researchers have studied this more closely than the University of Oregon psychologist Paul Slovic. Slovic has found that sympathy can begin to fade as soon as we’re presented with two needy people, rather than one37—what he calls the “arithmetic of compassion.” Counterintuit
ively, instead of concern and our willingness to act rising as the size of a potential catastrophe grows, it can actually contract. In one telling experiment, Slovic told volunteers that they could spend $10 million to save 10,000 people from a disease that killed 20,000 people per year, or spend the same amount of money to save 20,000 people from a disease that killed 290,000 people per year. The study subjects preferred to save 10,000 people from the disease that killed 20,000 people—even though the same amount of money could have saved twice as many people if it had been used to treat the more deadly disease.38
The psychic numbing that Slovic identifies makes it that much more difficult to come to grips with existential risks of any sort—including the ones, like nuclear war and climate change, that result directly from our own actions. Rather than being motivated to prevent global catastrophes, we prefer to ignore them. And if we can’t accept those risks, we can’t do anything about them. In a 1982 address to the American Psychological Association, the behaviorist B. F. Skinner argued that there was “something in the very nature of human behavior” that blocks us from working to prevent huge catastrophes we have not yet experienced—which applies to every existential risk covered in this book. “Instead of our worry increasing as the size of the consequence increases, it degrades,” Slovic told me. “Our attention is scarce, and so is our ability to worry. We treat these catastrophes as if they’re impossible unless there’s an experiential aspect that lends an air of reality to it.”
But the bomb seemed to—and still does—defy reality. Like all existential risks, nuclear war really was unthinkable to most people, as in it couldn’t be thought of. This was true even among the few who could testify to that reality: the survivors of Hiroshima and Nagasaki. The psychiatrist Robert Jay Lifton, who studied the aftermath of the bombings, found that survivors were deeply confused about what had happened to them. They had no previous model that could help them grasp the experience of a nuclear bomb. The survivors, Lifton writes, “wondered whether it was a huge ‘electric short,’ a form of ‘Buddhist hell,’ or ‘the end of the world.’”39