Most science involves careful assumptions, followed by rigorous experiments to test those hypotheses before something can be learned. But sometimes it’s more about dipping your finger in a dubious substance you find lying around the lab and tasting it (hence saccharin), or accidentally splitting an atom and not realizing it five years later.
Enrico Fermi, who completed the latter, was born in Italy in 1901 to the parents of a primary school teacher and a railway official and became known as “the architect of the atomic bomb”. At the age of 13, Fermi was recognized as a child prodigy by his father’s friend Adolfo Amidei, and Fermi received all the help Amidei could offer him in order to obtain his undergraduate degree.
Fermi excelled at university, and he found his career in academia, becoming a professor of theoretical physics at the University of Rome in his 20s. It was here that he split the atom, without noticing it.
In March 1934, following the discovery of artificial radioactivity by Irène Curie and Frédéric Joliot, Fermi attempted to produce radioactivity. If successful, it would mean artificial radioactivity could be created without involving particle accelerators.
“A number of small cylinders consisting of the elements to be studied are exposed to radiation from this source for anywhere from a few minutes to a few hours,” Fermi explained of his experimental setup.
“These cylinders are then quickly placed around the wire counter. The outer walls of the counter consist of a thin layer of aluminum, about 0.2 millimeters thick. [0.008 inches] thick so that possible beta rays may pass through and enter the counter. “
“So far, the experiments have turned out well, with two elements.”
In October, the team noticed erratic results while experimenting with silver. The level of radioactivity measured after the experiment varied depending on where the metal was placed in the lead container. They conducted experiments by placing the material between a radon-beryllium neutron source and silver.
Fermi suggested using paraffin. When the results came in, they found that the radiation in the silver had increased about a hundredfold. Fermi speculated that the neutrons had been “slowed down” by the hydrogen atoms in the paraffin, meaning that more collisions were likely to occur when they collided with the silver. This discovery paved the way for the first nuclear chain reaction in 1942, by slowing down neutrons in the same way as Fermi.
He received the Nobel Prize in 1938 “for his demonstration of the existence of new radioactive elements produced by neutron irradiation, and for his related discoveries of nuclear reactions induced by slow neutrons.”
As impressive as this was, Fermi missed the fact that he also became the first person to split an atom. In 1939, German scientists conducted the same experiment and found that neutron bombardment of uranium resulted in two different products with similar atomic weights. They concluded that five years ago, Fermi had been producing uranium fission, the splitting of an atomic nucleus into two or more smaller nuclei. He split the atom.
As Fermi then realized, this had some world-changing implications. When a neutron collides with a uranium atom and splits it, more neutrons are released, which then collide with other uranium atoms, repeating the process over and over again. In addition to paving the way for nuclear energy, this principle was also used to create nuclear bombs. If he had noticed at the time, who knows how World War II would have ended, with the possibility of nuclear weapons getting closer and closer.
