• Choose a category
• All
• Classic-Fiction

By Root 1324 0

This was, of course, impossible. The most rigid laws of physics, the laws of thermodynamics, seemed to forbid the spontaneous creation of energy. But the Curies were quite certain of what they were observing. A hunk of radium constantly produced heat like a little oven; every hour, a chunk of radium generated enough heat to melt its own weight in ice. It would do this, hour after hour, day after day, and year after year. No chemical reaction could possibly sustain itself for so long and generate so much energy. Whenever the Curies cooled a piece of radium, it would heat itself back up. Indeed, the radium would always be hotter than its surroundings, even though there were no external sources of heat. Marie Curie herself was baffled. She suspected that some sort of change was happening at the center of the radium atom, but she didn’t know what it could be—or how such a tiny chunk of matter could produce so much energy.

The answer would come a few years later when the young Albert Einstein formulated his theory of relativity. The theory revolutionized the way scientists perceive space, time, and motion. One of the equations that came out of the theory was E = mc2, the most famous scientific equation of all time. E = mc2 showed that matter, m, could be converted into energy, E. This was the secret to the seemingly endless fountain of energy coming from radium.

If you put a gram of radium in a sealed ampule, over many, many years the radium (a whitish metal) will gradually disappear. In fact, the atoms of radium spontaneously split apart and vanish from view. But they don’t disappear entirely. When an atom of radium breaks apart, it tends to split into two smaller pieces. The heavier of the two is a gas known as radon; the lighter is helium, and the Curies detected both helium and radon emanating from their radium sample.

Radium—a big heavy atom—breaks up into helium and radon, and when scientists looked carefully at the weights of those atoms, they realized the source of the heat. Some of the mass of the radium was missing. If you add up the mass of one atom of radon and one atom of helium, they make up 99.997 percent of the mass of the radium atom from which both sprang. The other 0.003 percent simply vanishes. When radium breaks apart, the parts are lighter than the original atom.

Here was the answer to the puzzle of excess energy. The whole atom weighed more than the sum of the parts. When the radium atom spontaneously broke apart, some of its mass changed into energy, just as Einstein’s equation allows. The m had become E. The missing mass was only a tiny fraction of what made up the atom, but even tiny chunks of mass are converted into enormous amounts of energy. It was energy on a scale much, much greater than humans had ever accessed before.

As World War II loomed, scientists began to realize that this energy could become a potent weapon. Less than a month before Germany invaded Poland in 1939, Einstein warned President Franklin Delano Roosevelt of the possibility of a bomb made from uranium, a metal that, like radium, releases energy when it breaks into pieces. Such a bomb would be extremely powerful—and there were ominous signs that the Nazis were already on their way to building one. For example, Germany had halted the uranium trade in occupied Czechoslovakia.

Uranium—in particular, one variety known as uranium-235—is an ideal material for a weapon. Its atoms are very sensitive; hit one with a subatomic particle and it fissions into fragments. Unlike decaying radium, which tends to cleave cleanly into two parts, a fissioning uranium atom shivers into a number of smaller chunks, including a handful of neutral particles known as neutrons. These neutrons then fly away from the shattered atom.

In a vacuum, the neutrons continue merrily on their way without bumping into anything else. However, a chunk of uranium is not a vacuum; it is a space crowded full of billions and billions of other uranium atoms. Once a single atom splits apart, within a tiny fraction of a second the resulting neutrons might slam into two