He may not be as famous as J. Robert Oppenheimer, but Enrico Fermi’s experiments are what
led to the creation of the atomic bomb. Growing up in Rome, his brightness caught
the attention of his father’s colleague, railway engineer Adolfo Amidei who
guided him and taught him far more about math and physics than he
was learning in high school. Had he not nurtured the 13-year-old Enrico,
history might have turned out differently. By the time Enrico entered university in 1918
to study physics at the prestigious Scuola Normale Superiore in Pisa, there really wasn’t
anything more his professors could teach him.
So he spent a lot of time studying
quantum physics and relativity on his own. He was thoroughly impressed with Einstein’s
Special Theory of Relativity, particularly his equation E = mc2, which shows that mass
and energy are different forms of the same thing…and that a small amount of mass can
be converted into a large amount of energy. As a student, he wrote: “If we could
liberate the energy in one gram of matter we would get more energy than
exerted by a thousand horses working continuously over three years…an explosion
of such an awesome amount of energy would blow to pieces the physicist who had the
misfortune of finding a way to produce it.” These words were prophetic, given his later work developing the
deadliest weapon known to humankind. After studying in Pisa, he went off
to the University of Gottingen in Germany, where the Italian was
overlooked by his counterparts. Marie Curie apparently “...ignored him
to the point of exceeding rudeness,” according to a future colleague of his on
the Manhattan Project to build the bomb. As he had done in Pisa, he focused
on probability theory in Germany. His mastery of probability allowed him to
make accurate predictions with minimal data, a vital piece in figuring out
how to create the atomic bomb. According to biographer David Schwartz,
Fermi’s interest in probability theory may have been sparked by the death
of his beloved brother Giulio, who died during an operation on a
throat abscess at just 15 years old. Schwartz surmises, “Fermi may have taken away
from this trauma the need to understand the likelihood of any particular event and a feeling
that in understanding that probability he was in a better position to anticipate it, prepare
for it, and perhaps even shape its outcome.” His set of guidelines called
Fermi-Dirac statistics, developed in tandem with English
physicist Paul Dirac, rely on the use of probabilistic reasoning to predict the
energy levels of particles called fermions. Imagine particles are concertgoers,
and their energy levels are seats. Just as each person has a unique seat,
each particle has a unique energy level. Just as no two people can share a seat, no
two particles can share the same energy level. His development of Fermi-Dirac statistics
propelled him from his job teaching at the University of Florence to a prestigious
position at the University of Rome, where he became Italy’s first
professor of theoretical physics. He sought to establish Rome as
a leading center of physics and was a natural leader others gravitated toward. In the Italian capital, he developed
his explanation of beta decay, a process where unstable atoms break down
and emit a specific type of radiation. Fermi proposed that inside these decaying atoms, one of the neutrons is turning
into a proton. When this happens, the neutron releases an electron and a tiny,
almost massless particle called a neutrino. Although this theory solidified his
reputation as a leading physicist, it was his later experiments developing the atomic
bomb that catapulted him into the limelight. He built on the work of Marie Curie and
her husband, Pierre, who discovered that bombarding substances with tiny particles called
alpha particles could make them radioactive. Inspired by the Curies, Fermi did something
similar using neutrons and discovered that certain elements bombarded with
neutrons also become radioactive. Fermi thought he had created new elements. He even won the Nobel Prize in
Physics in 1938 for this discovery. But what he had actually
done, was split uranium atoms, a process that is fundamental to
the operation of an atomic bomb. He didn’t realize it because
he thought the nucleus of a uranium atom was like a solid brick
wall, incapable of changing shape. It wasn’t until German physicists
replicated his experiments five years later that they made a monumental
discovery; they realized firing neutrons at uranium splits the uranium atom,
a process called nuclear fission. This releases an enormous amount of energy,
which is fundamental to nuclear weapons. Fermi found out about his embarrassing
overlook after he moved to America in 1939. Fascist Italy had become intolerable by then. Fermi had actually joined the Fascist party
earlier as it was common for career advancement. However, as Hitler pressed
Mussolini to target Italian Jews, there was fear that his wife, Laura,
who was Jewish, would be persecuted. Another incentive to leave his homeland was that
the physicist and politician Orso Mario Corbino, who had guided his career and opened doors
for him, had died suddenly from pneumonia. After Corbino’s death, funding
for his research began to dry up. Fermi took the opportunity of collecting
his Nobel prize at the Awards ceremony in Stockholm to the quietly head to New
York with his wife and two young children, where a position awaited
him at Columbia University. Two weeks after arriving in
America on January 2, 1939, he learned about the major discovery of
nuclear fission that he should have made. But there was no time to
dwell on missed opportunities. Besides, the process of fission
was not fully understood. He joined forces with another
recent American immigrant, Hungarian physicist Leo Szilard to understand and
control each step of the chain reaction process. They aimed to harness the enormous amount of
energy liberated within a fraction of a second, opening up the possibility that
uranium could be used for power generation or, potentially, to build a bomb. They were aware of the implications of
their work in light of the escalating tensions that would eventually lead
to WWII and informed the U.S. Navy. The dean of graduate studies at Columbia,
George Pegram sent a letter to Admiral Stanford Hooper outlining the potential
consequences of Fermi’s research: “...this might mean the possibility that
uranium might be used as an explosive that would liberate a million times as
much energy per pound as any known explosive. My own feeling is that
the probabilities are against this, but my colleagues and I think the bare
possibility should not be disregarded…” The U.S. Navy gave Fermi a small
$1,500 grant to continue his work. The government’s interest in Fermi’s research only intensified after Szilard wrote a letter
to President Roosevelt clearly spelling out that “extremely powerful bombs of
a new type may thus be constructed”. He warned that Nazy Germany was demonstrating
a keen interest in uranium research, hinting at their pursuit of a nuclear weapon. The most famous scientist
in exile, Albert Einstein, signed the letter to give it extra clout. The U.S. government would eventually spend
$2.2 billion to build the first atomic bomb. Scientists had to figure out how much
uranium would be needed to create a bomb, and how to assemble the bomb in such
a way that it would explode properly. J. Robert Oppenheimer oversaw the
Manhattan Project, coordinating the many teams who worked on different
aspects of the bomb’s development. The Manhattan Project was so secretive that most
staff had no idea what they were working on. Fermi was primarily responsible for
developing the first nuclear reactor, which demonstrated that a nuclear chain
reaction could be initiated and controlled. By then, he had moved from Columbia to the
University of Chicago at the request of the U.S. government, which wanted to consolidate all
the nuclear research projects across the country. On December 2, 1942, he and his team
conducted a nuclear experiment beneath the University of Chicago's abandoned
football field, in the squash court area. It was the only space with high enough
ceilings to allow the construction of the pile of bricks of graphite and uranium,
carefully arranged to facilitate a reaction. The graphite slowed down the speed of the neutrons
so that they could cause further fissions. This atomic furnace, called “Chicago Pile-1”, demonstrated the first self-sustained chain
reaction, ushering in the nuclear age. When Fermi realized the reaction
was self-sustaining, “...his whole face broke into a broad smile,” described
David Schwartz in his biography on Fermi. tephen
A member of Fermi’s team recorded the moment in
a logbook, writing: “We’re cookin’!”. The team shared a bottle of wine to mark the
occasion, but they didn’t make any toasts. This wasn’t really a celebratory moment, as they
knew the implications of what they had achieved.
The Chicago “pile” was the predecessor to the
giant nuclear reactors at Hanford, Washington. The U.S. government acknowledges Fermi’s
pivotal role in creating the bomb, declaring, “More than any individual, he was responsible for developing a means for
the controlled release of nuclear energy.” Yet, Oppenheimer has gotten
far more credit than Fermi. One reason is that Fermi rarely appeared on TV, and he wasn’t into self-promotion. And he also
passed away before television became widespread. On the other hand, Oppenheimer was
often interviewed and photographed as the leader of the Manhattan Project. Oppenheimer recognized and acknowledged
Fermi’s contributions and intellect. At a dinner party after Fermi’s death, Manhattan Project physicist Leona Libby
recalled that Oppenheimer suggested a game he called “Who do you want to be on
your day off?” and then, he chose Fermi. In 1944, Fermi moved to Los Alamos, New Mexico, the main hub for the Manhattan Project,
where he became an associate director. He served as an advisor, offering advice to
other scientists when they ran into problems. On July 16, 1945, scientists detonated the first
nuclear device near Alamogordo, New Mexico. Fermi made a rough calculation of
its explosive energy by dropping small pieces of paper from his hand as the
shockwave arrived and estimated from their deflection that the test had released
energy equivalent to 10,000 tons of TNT. The actual result was more than
twice that amount, 21,000 tons. This is enough energy to power two
million American homes for a year. The Trinity device unleashed at
Alamagordo had a plutonium core, which Fermi and his team achieved
through a series of transformations with uranium that resulted in the
creation of the human-made element. This design was later replicated in one of
the two devastating bombs dropped on Japan. We don’t know how Fermi reacted to the bombing
of Hiroshima and Nagasaki and the hundreds of thousands of people who perished instantly or who
later died from injuries and radiation sickness. He kept his emotions to himself. What we can glean is that during
the development of the bomb, Oppenheimer recalled Fermi was surprised
by the group’s enthusiasm for building such a weapon and remarked, “I believe our
people actually want to make a bomb.” Fermi’s sister Maria did hold strong
views and wrote to her brother: “All, however, are perplexed and
appalled by its dreadful effects, and with time the bewilderment
increases rather than diminishes. For my part I recommended you to God,
Who alone can judge you morally.” After the war, Fermi opposed
working on the hydrogen bomb, which is orders of magnitude more
powerful than the atomic bomb, on moral and technical grounds…though
he still contributed as a consultant. The detonation of an atomic bomb by the Soviet Union in 1949 sparked Washington’s
interest in a more powerful weapon. Oppenheimer strongly resisted working
on the hydrogen bomb and faced hearings that questioned his loyalty,
suspecting him to be a Soviet spy. Despite Fermi and other
scientists coming to his defense, Oppenheimer had his security clearance revoked. Fermi went on to become a distinguished professor of physics at the University of Chicago,
where he was regarded as a superb teacher. During his later years, he raised an interesting
question while lunching with colleagues: “Where is everybody?” He was asking why no extraterrestrial
civilizations had been discovered, despite the great size and age of the universe. This is referred to as a Fermi Paradox because
it’s an apparent contradiction between the high probability of the existence of aliens due to the
vast number of stars that can potentially host habitable planets and the lack of human contact
with such civilizations or evidence for them. Fermi’s view was that if intelligent
life existed elsewhere in the universe, we should have been visited by them long ago. While Fermi contemplated the vastness
of the universe, a more immediate, personal concern soon cast a shadow over his life. His health had started to decline. In the summer of 1954, he was noticeably fatigued. He visited the doctor in that
fall and they discovered he had stomach cancer that had metastasized. He was given six months to live. Throughout his career, Fermi was
exposed to radioactive materials, which may have contributed to
the development of his cancer. Fermi was not a religious person, but as he lay
ill and dying, he received visits from priests. His Manhattan Project colleague Leona Libby
who frequently went to see him recalled: “He spoke of his approaching death as a
great experience, but he asked wistfully if I thought there was anything valid in the
idea of an afterlife. He was really cross about dying. I came out after each visit and
drove home with tears streaming down my face.” His condition deteriorated rapidly.
Two months after his diagnosis, on November 28, 1954, Enrico
Fermi passed away at his home. He was 53 years old. In an obituary, the New York Times wrote:
“More than any other man of his time, Enrico Fermi could properly be named
"the father of the atomic bomb." Fermi’s contributions touch our
lives beyond the realm of physics. Tech companies are known to ask candidates complex problems during job interviews to see if
they can emulate Fermi’s way of thinking. An example of a “Fermi problem” would be estimating the number of piano
tuners in a city like Toronto. Toronto has a population of
approximately 3 million people. If we assume an average of 2.5 people per
household, this gives us 1.2 million households. If we assume 1 out of every 50
homes has a piano, there would be 24,000 pianos in Toronto.
Since pianos are tuned once a year on average, there would be a
need for 24,000 piano tunings a year. If a piano tuner takes two weeks of vacation
a year, they work 50 weeks. If they tune two pianos a day, five days a week for
50 weeks, that’s 500 pianos a year. If there’s a need to tune 24,000 pianos a year,
and each tuner can handle 500 pianos a year, there’d be a need for 48 piano tuners in Toronto.
While this answer may not be precise, it's Fermi's approach to problem-solving
that resonates in our lives today. It's this kind of curious mindset that Brilliant
aims to cultivate in learners of all ages. I really enjoy Brilliant’s logic puzzles
to help sharpen my analytical thinking. Brilliant offers a hands-on, interactive
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people who sign up with my custom link will get 20% off their Premium subscription which
gives you access to all their offerings. Thanks for watching. I’m Cindy Pom.
