DESTROYER OF WORLDS: The Deep History of the Nuclear Age

Frank Close / cam.ac.uk

That is the title of the new book by Frank Close, an outstanding popularizer of science and an emeritus professor at the University of Oxford who specializes in particle physics. It tells the story of the curious path by which humanity entered the nuclear age. It all began with seemingly innocent laboratory curiosities, but a chain of discoveries eventually led to a weapon unprecedented in history. So what, in fact, did physicists release the power of the atom for?

LABORATORY TRICK

his story began, perhaps, with the discovery of electric current, for which solid materials were not an insurmountable barrier. It ended with the emergence of technologies capable of wiping entire cities off the face of the Earth… And it became possible because scientists are extraordinarily receptive to new knowledge, which instantly, like a virus, begins to migrate from one country to another. In the 1890s, the German physicist Wilhelm Röntgen discovered electric currents that he called X-rays.

They passed literally through everything, including his own hands and the hands of his wife. Perhaps this would have remained an innocent laboratory attraction if, in France, Antoine Henri Becquerel had not decided to test his idea about the connection between X-rays and phosphorescent minerals such as uranium. For several days he placed uranium crystals and a copper cross on a photographic plate inside a dark box. When he developed the plate, Becquerel saw the clear outline of the cross — in complete darkness the uranium had affected it just like the sun!

A STORM OF DISCOVERIES

Meanwhile, in Canada, Ernest Rutherford was measuring the energy released by uranium in a process that came to be known as «radioactivity». Rutherford argued that the atoms of radioactive elements such as uranium, radium, and thorium contain enough energy to release heat for thousands of years. Thus began the twentieth-century nuclear age, which inscribed dozens of brilliant names in the history of science: Marie and Pierre Curie, Irène and Frédéric Joliot-Curie, Albert Einstein, Otto Hahn, Lise Meitner, James Chadwick, Niels Bohr, Ettore Majorana, Enrico Fermi, and many other scientists. All of them sought to understand how atoms store and release this energy. As a result, they discovered that the atoms of radioactive elements naturally decay, transforming in the process from one element into another.

«HACKING» THE NUCLEUS

Such decay indicated that there must exist some entities «smaller than the atom». Scientists began searching for them and eventually, through experiments, discovered the electron and the atomic nucleus. Then they «broke into» this nucleus. Inside it they found other particles — first the proton, and later its companion, the neutron, which largely determine the mass of the atom. These nuclear particles turned out to be tightly bound to one another. Therefore, scientists asked themselves: is it possible to break the bond between them? To do this, devices were invented that made it possible to separate these particles and track the processes occurring during the separation. Scientists discovered that if a neutron is directed into a lithium nucleus, it splits into three parts — a helium nucleus, a tritium nucleus (an isotope of hydrogen), and an additional neutron.

THE DISCOVERY OF PRESSURE AND THE CHAIN REACTION

In nature, radioactivity is a natural phenomenon. It is caused by the decay of unstable atomic nuclei found in rocks, water, air, and even in living organisms. But in the twentieth century, people learned how to induce radioactivity artificially. First in light elements, and later in heavy ones. Scientists discovered that heavy radioactive elements naturally decay into elements located one or two steps lower in the periodic table. For example, uranium (element 92) turns into thorium (element 90). But when they began bombarding uranium with neutrons, its nucleus split almost in half, turning into barium (element 56). This process became known as «nuclear fission».

CHAIN REACTION

Then a remarkable phenomenon was discovered: the fission did not stop there. Uranium emitted neutrons that could split other uranium nuclei, releasing new neutrons, which in turn split other nuclei… This observed avalanche-like effect was called an exponential chain reaction. During this process, colossal energy was released — energy that had previously held the nucleus together. Scientists were able to quantify this energy: it equals the mass of the nucleus multiplied by the square of the speed of light. Only one step remained before the creation of the nuclear bomb.

NUCLEAR DETERRENCE — AN IDEA OF SCIENTISTS

In a certain symbolic sense, it can be said that nuclear weapons and the Second World War are contemporaries. On September 1, 1939, the day Germany invaded Poland, Niels Bohr published a fundamental work on the mechanism of nuclear fission. Six months later, in March 1940, Fermi and Peierls sent a letter to the British government. In essence, it outlined for the first time the principle of nuclear deterrence, which underlies modern military doctrines.

While expressing the hope that no civilized nation would use a nuclear device, the scientists nevertheless pointed out that the only protection against nuclear weapons is nuclear weapons themselves. If two sides possess nuclear weapons, any attempt by one side to launch a first nuclear strike will inevitably mean a retaliatory strike that will lead to the destruction of both sides. The risk of mutual annihilation must outweigh the «benefit» of using a nuclear bomb.

A DISSERVICE OF WAR

In addition to claiming millions of lives, the Second World War did humanity a disservice in another sense. If the world had not been engulfed in war, the next step after the discovery of the chain reaction would have been the design of nuclear power plants. But the possibility of gaining a decisive advantage over the enemy was far more attractive at the time than the prospect of producing cheap and widely available energy. And in Germany, nuclear physicists were fully engaged in the process of creating an atomic bomb.

At this point, the history of science ends and the history of nuclear bomb technology begins. By then it was known that the isotopes uranium-235 and plutonium-239 split most easily and efficiently. Scientists figured out how to concentrate the former and produce the latter, and they also calculated how much of each would be required to manufacture bombs. They built reactors in which chain reactions could be controlled.

THE MANHATTAN PROJECT: A YOUNG PEOPLE’S ENTERPRISE

However, there was a significant limitation — at that time, it was hardly within the power of any single state to quickly create a nuclear weapon ready for use. Great Britain, for example, clearly lacked the resources for this: turning uranium and plutonium into a bomb was beyond its capabilities. Therefore, the country delegated its scientists to the American Manhattan Project. In addition to British and American scientists, Jewish specialists who had fled Nazi persecution from continental Europe also took an active part in it. The project was not only enormous in scale but also remarkably «young». It involved 100,000 people whose average age was 24.

THE MOST «COMPACT» DEATH

The design of atomic bombs was developed with consideration for the characteristics of the element used to split the nucleus. The first plutonium bomb was tested in July 1945 at the Alamogordo test site in New Mexico as part of the Manhattan Project. Three weeks later, a similar device was dropped on the Japanese city of Nagasaki, while a uranium bomb was used in Hiroshima. Each bomb had the same destructive power as 20 kilotons of explosives in TNT equivalent. At that time, the world did not yet realize that a weapon of such devastating force could be so «compact.» The American bomber formation consisted of only three aircraft. The Japanese authorities decided that they could not pose a significant threat and did not consider it necessary to send people to shelters.

ORIGINALLY AIMED AT HITLER…

When the bombs were dropped on Japan, Germany had already been defeated. The United States repeatedly and convincingly justified the necessity of this step. However, nuclear weapons were used beyond the originally declared goal — the defeat of Adolf Hitler. And this still shocks people today. Meanwhile, the nuclear chain reaction triggered a political reaction — the nuclear arms race began. In 1949, the Soviet Union started testing its own nuclear bombs, while other nuclear powers turned their attention to even more powerful thermonuclear weapons.

HOW TO DESTROY THE EARTH IN YOUR «BACKYARD»

When a nuclear bomb explodes, the chain reaction stops. Therefore, its power is limited to about one megaton. This limitation can be bypassed by using not a chain reaction but thermonuclear fusion. It releases energy by forcing atomic nuclei to collide directly with each other — much like two stars colliding in space. This means that thermonuclear bombs are limited only by the amount of fuel. In other words, their power is essentially unlimited. The American physicist Edward Teller continued calculating ways to increase the power of bombs until he crossed the threshold of 10 gigatons. He called this bomb the «backyard», meaning that there would be no point in delivering such a bomb to a target — it would be enough to detonate it in your own garden, in the backyard, to destroy all human life on Earth.

THE MOST POWERFUL BOMB IN HISTORY

At first, thermonuclear bombs were difficult to detonate, and work in this direction stalled. That was until Fermi proposed using a nuclear bomb to «trigger» thermonuclear fusion. The idea was implemented in October 1952 during the test of the 10-megaton thermonuclear bomb Ivy Mike. Soldiers observing the explosion from a distance of 30 kilometers briefly saw the shadows of the bones in their comrades’ skeletons. Two years later, a similar thermonuclear bomb was tested in the USSR. In 1961, the Soviets reached the peak of their symbolic gigantomania by detonating the most powerful bomb ever created — the 50-megaton Tsar Bomba. It was too heavy to be transported and therefore had no military use, although it was capable of destroying an entire city.

HOW RELIABLE IS THE NUCLEAR «SAFETY CATCH»?

It is unknown where such terrifying experiments might have led humanity. To its credit, in 1963, a treaty was signed banning nuclear tests worldwide. And we see that the principle of mutually assured destruction still functions as a universal «safety catch». But how reliable is it in reality? And along which path will humanity continue to develop nuclear technologies? The technologies of fission and fusion are capable of destroying and intimidating. But they also allow people to live with greater convenience and comfort. At the same time, it must be acknowledged that nuclear power plants, as sources of energy, have had a rather unstable history and a poor reputation. And thermonuclear power plants, if forecasts are to be believed, will not appear for at least another 20 years.

Original research: