Stealing the Sun ― The Day the Atomic Door Opened

Why has the sun we gaze upon been able to keep burning for billions of years? Without firewood or oil, it lights the Earth and pours out the vast heat that nurtures life. The secret, it is thought, lies in the fact that when atomic nuclei join together at the sun’s core, a tiny amount of mass transforms into an enormous quantity of energy. What makes the stars shine is a force that sleeps in the depths of the atom.

There was an era when human beings on the ground began to lay their hands on that force. In the first half of the twentieth century, a single discovery was born in a European laboratory, and the scientists would in time realize something: that they might be drawing the fire of the stars down to the Earth. This is the story of the beginning—of how humanity came to know the art of ‘stealing the sun.‘

A single paper that hinted at an immense force

The distant origin of this story goes back to 1905. That year, an unknown young man named Einstein, working at the Swiss patent office, put out several papers. In one of them, it is said, was written a relation that would later shake the world. Mass and energy are essentially two faces of the same thing, and each can change into the other—E=mc², the equation that everyone today has surely seen at least once.

What this equation declared was the fact that a mere sliver of mass could turn into an amount of energy multiplied by the staggering number that is the speed of light squared. In theory, if a grain-of-rice’s worth of mass were entirely converted into energy, an unimaginable heat and light would be born. Yet at the time, this remained a matter only on paper. How could that force sleeping within the atom be drawn out? The entrance to it was not yet visible to anyone.

Over the following decades, physicists gradually unraveled the structure of the atom. At the center of the atom lies a small, heavy ‘nucleus,’ and within it is packed a force of unknown nature. When the particle called the neutron was eventually discovered, scientists began to fire it like a bullet into atomic nuclei to see what would happen. Step by step, humanity was drawing closer to the door that led on to the fire of the stars.

1938, the winter uranium split

The stage shifts to Berlin, on the eve of the Second World War. At the Kaiser Wilhelm Institute for Chemistry, the chemists Otto Hahn and Fritz Strassmann were repeating experiments in which they bombarded uranium with neutrons. At the close of 1938, the two ran up against a strange result. Among the substances left after the uranium had been exposed to neutrons, barium—an element far lighter than uranium—had appeared.

This was an occurrence that the common sense of the time could not explain. When struck by a neutron, an atomic nucleus should become slightly heavier, or at most chip away a little. And yet here it had turned into an element about half its weight. Even Hahn, who had carried out the experiment with a chemist’s precision, could not immediately explain what had happened. He wrote of this baffling result in a letter to a former research partner.

That partner was none other than Lise Meitner. An Austrian-born physicist who had long worked alongside Hahn, she was of Jewish descent and had been driven out of Germany under the Nazi regime; at this time she was in exile in Sweden. Receiving the letter, Meitner is said to have discussed the riddle while walking through the snow with her nephew, the physicist Otto Frisch. And the two arrived at one bold answer. The nucleus of the uranium atom, struck by a neutron, had split in two.

Meitner and Frisch noticed that when they added up the masses of the fragments left after the split, the total was slightly lighter than the original uranium. Where had that vanished mass gone? Surely E=mc² crossed their minds. The lost mass had transformed into an immense quantity of energy—here, the equation on paper and the reality of the laboratory were joined into one. The very principle that makes the stars shine had, beyond doubt, occurred within a small vessel on the ground.

The two premonitions the scientists held

The news of nuclear fission raced among the world’s physicists at astonishing speed, even as the footsteps of war grew louder. And many scientists, almost simultaneously, sensed two things. One was a prospect that resembled hope: that if new neutrons were also flung out when uranium split, they would split the next uranium, and then the next—through a chain reaction, one might draw out energy all at once.

The other was a darker premonition. If that force were released in an instant, it could become a weapon of destruction unlike anything before. And as it happened, the first to confirm nuclear fission had been a laboratory in Germany under Hitler’s regime. The scientists who were in exile in America came to hold a deep fear that Nazi Germany might be the first to forge this force into a weapon.

It was the Hungarian-born physicist Leo Szilard and others who turned that anxiety into action. They sought the cooperation of Einstein, the most famous scientist in the world. In 1939, a letter signed by Einstein is reported to have been sent, addressed to President Roosevelt of the United States. In it, it is said, was written that an extraordinarily powerful new kind of bomb using uranium could become reality, and that there was a danger Germany might get there first.

There are various views as to whether the letter was truly one of the things that gave the push, but America did eventually set in motion serious research concerning uranium. In December 1942, Enrico Fermi and his colleagues are said to have succeeded, for the first time in history, in producing a controlled chain reaction using a device assembled beneath a stadium at the University of Chicago. The fire of the atom had now become something that human hands could kindle and sustain.

And so, within the laboratory, humanity took hold of a fragment of the sun’s fire. Yet that fire would be raised into an entirely different form—not as a peaceful light, but under the will of a vast nation. On a desolate desert highland, a secret town would be built, and minds gathered from around the world would begin to run toward a single purpose. The immense power glimpsed beyond the atomic door was, at last, beginning to take on the outline of a weapon.