Fermi

** Enrico Fermi [[image:http://newsletter.vonfrederick.com/images/fermi.jpg]] ** By Scott McKean
 Enrico Fermi was one of the greatest scientific minds that has ever lived. He was both a theorist and an experimentalist, and his intellectual capabilities were beyond the understanding of many people during his time. Fermi was born on September 29, 1902 to Alberto Fermi and Ida de Gattis in Rome, Italy. His father was an inspector on the railways, and his mother was an elementary school teacher and was the major influence on Fermi and his older brother Giulio and older sister Maria. When he started school at the age of six he could already read and write. Fermi showed very strong skills in mathematics and also demonstrated an extremely good memory. While he was young, Fermi's best friend was his older brother, Giulio. Tragedy struck the Fermi family in 1915, when Giulio died during a routine operation to remove a throat abscess. Fermi was so sad that all he could think of doing was burying his head in his books. Even though this was a tragedy in Fermi's life, it resulted in him becoming one of the greatest mathematicians of all time.  After the death of his brother, Fermi found an adult friend. He became friends with one of his father's co-workers, Adolfo Amidei. Amidei was intelligent in both science and math. Fermi admired him and asked him many questions. Amidei was very impressed with Fermi's intelligence, and gave Fermi books for him to study. The textbooks that Amidei lent to him were books on proj ective geometry, al gebra, trigonometry, analytical geometry, and calculus. Fermi showed an extremely high ability to comprehend the material and an amazing talent to memorize, or easily derive, any passage of physics or formulas he needed to solve complicated problems. After being tutored by Amidei, Amidei recommended that Fermi enroll at the University of Pisa.  The top forty students in Italy went to the Scuola Normale, which is a part of the University of Pisa. When Fermi applied to the Scuola Normale the examiner of his essay on the "Characteristics of Sound" was so impressed with Fermi's higher math ability that he said that Fermi would definitely receive a scholarship to the school and someday become an important scientist. At the Scuola Normale he became good friends with Franco Rasetti, a physics student who lived with his mother. Over their lifetimes they ended up doing a lot of research together. Rasetti was more of an experimentalist, while Fermi was more of a theorist, so together they were a powerful team. Fermi enjoyed doing research and teaching, but he also loved to have fun. He would often lead hiking trips with his friends in the Dolomite Mountains in Italy. He also liked to come up with mischievous pranks to pull on his friends and at school. One time he set off a stink bomb in the middle of a lecture and this almost got him and Rasetti expelled. Fermi worked hard at his studies, but he enjoyed them very much, and he was always thinking about things and why they were the way they were, even when he was having fun.

In 1924, one of the friends that Fermi used to enjoy hiking with introduced him to Laura Capon, who was sixteen years old at the time and he was twenty two. The two didn't meet again until 1926 when they became better friends. They married on July 19, 1928 and had two children, a daughter, Nella, and a son, Giulio. They took many trips together and Fermi even tried to teach her physics. They enjoyed traveling and raising their children together. Laura turned out to be a good influence on Fermi, because she challenged him and didn't mind that he did work, often writing papers and books, during their vacations. Fermi published his first theoretical paper in January 1921, and chose to do his research for his doctor's degree on X-ray diffraction. When he presented his work to the faculty committee he overwhelmed them with his knowledge. However, at the time theoretical physics was not recognized as an acceptable topic by Italian universities. Fermi received his doctorate with high honors in July, 1922, but the university refused to publish his work and considered it controversial. Later that year, Fermi published a paper that dealt mathematically with Einstein's theory of relativity. This got him recognized as an authority, while he was only twenty two years old. After Fermi completed his Ph.D. in physics he went back to Rome to his family. Fermi wanted to work with professor Orso Mario Corbino, who was director of the physics lab at the University of Rome. Corbino liked and respected Fermi, but there were no openings to be a professor at the university. In the first half of 1923, Fermi went to the University of Gottingen in Germany to work with Max Born, under a government awarded scholarship. He was then appointed to teach mathematics to scientists at the University of Gottingen for the academic year 1923-24. He didn't really feel like he belonged there and returned to Rome at the end of the year. Fermi worked as a teaching assistant at the University of Rome, and then had an assistantship at the University of Leiden for three months. He also taught at the University of Florence as a lecturer in mathematical physics and mechanics. It was there that he met up with his friend, Rasetti, again. During this time Fermi published a large number of papers, trying to establish himself in the field of physics.

In 1925, Fermi was teaching at the University of Florence and was interested in mathematical explanations of the behavior of atoms and electrons. Another physicist, Wolfgang Pauli, had "discovered the principle of exclusion, which says that in each orbit or at each energy level of the nucleus of an atom, there can be at most two electrons, but these must have opposite spins" (__Enrico Fermi: Trailblazer in Nuclear Physics__, pg. 34). Fermi showed mathematically that no two atoms of a gas can move with exactly the same velocity. This was Fermi's first major contribution, and this theory became known as the Fermi-Dirac statistics. After this, he won the competition to earn a spot as a physics professor at the University of Rome in 1926. Professor Corbino built a team made up of Fermi, Rasetti, and two engineering students that brought great recognition to the University of Rome. Fermi was a slow and steady worker and could take a complicated problem and reduce it to simpler steps. The team developed long lasting friendships, but eventually they separated to learn from other laboratories. Fermi took a position to teach at the University of Michigan in 1930. This was the first time he visited the United States.



In 1933, Fermi made what he considered his most important achievement, known as the beta decay theory. This was a mathematical explanation of what makes a neutron in certain radioactive elements split into a proton and electron. It raised a lot of questions, such as why a nucleus was held together. A new constant, now called the Fermi constant, was needed to make the math come out right. Fermi showed that beta decay involved the creation of both an electron and a neutrino, an effectively massless particle he named (__The Scientific 100__, pg. 168). With this discovery, Fermi proposed there was a "weak force" responsible for beta decay. The weak force became one of the four fundamental forces in physics and was important for the later development of nuclear physics. After this discovery Fermi became more of an experimentalist, and got further into the study of radioactivity.

BETA DECAY >

In 1934, Curi and Joliet showed that radioactive elements were created by bombarding the nuclei of known elements. Fermi studied this further and made another interesting discovery. He discovered the effect of slow neutrons, which eventually lead to the discovery of nuclear fission. Other scientists were able to use his work and results to create new elements. He was awarded the Nobel Prize in Physics in 1938 for his work on artificial radioactivity. Around this same time, Italy was becoming anti-Semitic. Even though Fermi was not Jewish and he was appointed to his position at the University of Rome by Mussolini, the dictator, Fermi was concerned because his wife, Laura, was Jewish. Fermi wanted to keep his wife and family safe, but he was concerned that the government would not let him leave Italy. Secretly, Fermi wrote letters to many universities in the United States, and obtained a position at Columbia University. Fermi and Laura took their two children with them to the Nobel Prize presentation ceremony in Stockholm, where Fermi received the Nobel Prize for his work, and did not return to Rome. After a few short stops in Copenhagen and England, the family immigrated to the United States.

Fun Fact:  When Fermi arrived in the United States, January 2, 1939, amusingly for Fermi, he had to take a arithmetic test to be granted a visa.

At Columbia University Fermi taught physics, and passed on his enthusiasm to his students. In 1939 the discovery of fission, which Fermi had barely missed discovering several years before, revealed to physicists the dramatic possibility of creating a chain reaction with great explosive potential (__The Scientific 100__, pg. 169). Fermi had become an expert in neutrons and atomic behavior, and did research at Columbia on chain reactions. Scientists knew that there was enormous potential if the explosive power of fission could be captured that an extremely devastating bomb could be produced. By this time, World War II had already started in Europe. A National Defense Research Committee was set up because President Roosevelt was advised that if the information on fission and nuclear chain reactions fell into the wrong hands, it could become a very dangerous situation. Fermi was only interested in fission as a natural process that would help in the studies of atomic nuclei. At Columbia he also worked with the university's cyclotron, which was a particle accelerator. Fermi tried to focus on the science and teaching and tried to avoid the politics.



In 1941, Fermi was reluctantly drawn into the work that would in time produce the atomic bomb. Fermi lead a group of scientists at Columbia to gain a better understanding of the neutrons emitted by uranium and plutonium. Eventually he moved to the University of Chicago with his group because they needed more space to build a nuclear reactor or "pile" as Fermi called it. Fermi and his group built a reactor in a squash court underneath a football stadium in Chicago. Their goal was to show if a chain reaction could be self sustained. If it could be, and the released energy could be contained in some way, it could be used as a massive bomb. The pile was made of pure uranium, and uranium oxide, and it consisted of 40,000 pounds of graphite bricks to diffuse the nuclear reaction throughout the structure. To control the reaction, cadmium sheets nailed to wooden rods were inserted into the pile (__Enrico Fermi: Trailblazer in Nuclear Physics,__ pg. 83). Cadmium is a strong neutron absorber and was used to control the reaction. This pile was used to generate the world's first controlled, man made, self-sustained nuclear reaction on December 2, 1942. The chain reaction lasted for twenty eight minutes. FERMI'S NUCLEAR PILE >

**MY FAVORITE FACT** **:** In the summer of 1944, Fermi worked with a group of men to develop and build a nuclear bomb at a lab in Los Alamos, New Mexico. Fermi served as a general consultant in the later stages of what became known as the Manhattan Project. When any of the scientists in the group had a problem, they would go to Fermi for help with solving it. The Manhattan project was a top secret project, and the government did not want any information on it to leak out, especially to other countries. All the scientists working on the bomb were given a code name, and Fermi's was Eugene Farmer. As part of this work, Fermi was involved in one of the most important physics experiments, given the code name "Trinity", which was to build a nuclear bomb and test it. They built a bomb containing plutonium-239 and detonated it in the desert. The group's work lead to the creation of the nuclear bombs that were dropped on Hiroshima and Nagasaki to end World War II.

This was my favorite fact because Fermi actually developed a bomb that had a massive amount of explosiveness. I was interested in how Fermi and his group were able to discover and design something with so much power, and how they got a huge amount of energy from something that we can't even see!



After the war, Fermi went back to the University of Chicago were he worked as a professor at the Institute for Nuclear Studies. Students loved to be taught by Fermi, because of his enthusiasm and love for science and teaching. Towards the end of his career Fermi became interested in particle physics, and worked with particle accelerators. He developed a statistical theory of interactions between mesons, which were particles that have a mass between that of a proton and an electron, and protons (Enrico Fermi: Trailblazer in Nuclear Physics, pg. 104).

Fermi was recognized as one of the greatest minds of the twentieth century. He had an amazing ability to understand problems, come up with solutions, and always had precise calculations. He received many honors and awards throughout his career, and many things have been named after him. Electrons, protons, and neutrons are referred to as fermions, which is the name given to any particle that obeys Fermi-Dirac statistics. The 100th element in the periodic table, discovered in 1952, was named fermium. A very small unit of length (10 to the negative thirteenth) used in nuclear physics, is called the fermi. The accelerator laboratory built in the late 1960's near Chicago is called the Fermi National Accelerator Laboratory, or Fermilab for short. The Institute where Fermi last worked is now named the Enrico Fermi Institute. And the Italian summer school that Fermi lectured at during many summer months is also named after him. There are also other schools and nuclear power plants named after Fermi to honor his many contributions to the world.

The Atomic Energy Commission (AEC) gave Fermi a special award of $25,000 for his achievements, just before he died. The highest award given by the AEC since then is named the Fermi Prize. It is given each year "to recognize someone of international esteem, whose career has been marked by continued exceptional contributions to the development, use, or control of nuclear energy" (__Enrico Fermi: Trailblazer in Nuclear Physics__ pg.112).

Fermi always loved to hike in the mountains, and in the summer of 1954 while he was in Europe teaching a course on nuclear particles, he tried to enjoy his favorite activity. He didn't have his usual stamina and when he returned to Chicago doctors found that he had stomach cancer. Unfortunately, this was probably related to his work on the nuclear pile. Fermi knew his work carried risk, but he considered the outcomes so important that he took such risks. While Fermi was in the hospital, his friends found him timing the drops from the nutrient solution dripping into his veins and calculating the rate of flow, just like he loved to calculate in his experiments ( __Enrico Fermi: Trailblazer in Nuclear Physics__, pg. 110). Fermi died in the hospital on November 29, 1954, just two months after his fifty-third birthday. Fermi was remembered by his friends as a modest, conscientious, kind, disciplined and helpful man with special talents. Fermi wanted to gain a better understanding of the physical world, but he realized that every time physicists answered one question, more questions presented themselves.





