Enrico Fermi

If you are a genius, change the course of human history, and win a Nobel Prize in physics, you could get some bubbles named after you.

Enrico Fermi was born in Rome in 1901. His mind developed quickly, and at the age of 21 he earned a doctorate in physics from the University of Pisa, the same university where Galileo had studied in the 1580s. For a few years Fermi taught physics in Italy, making such a strong impression that Italian dictator Benito Mussolini appointed him to the prestigious Academia d’Italia and he was given the title of ‘excellency’. Fermi was 28 years old making him the youngest person to receive the honor.

Although physicist Sir James Chadwick discovered the neutron in 1932 for which he won the 1935 Nobel Prize in physics, it was Fermi who soon became the world’s greatest expert on how to put it to use. Unlike protons with a positive electrical charge and electrons with a negative charge, neutrons have no charge and this allows them to penetrate into the atoms of materials that would electrically repulse a charged particle. Fermi learned how to make use of the neutron’s ability to be shot into atoms and split them apart.

In 1934 while he was a professor at Rome University, Fermi and his colleagues figured out how to bombard streams of chargeless neutrons into the atoms of various elements and were able to study the subatomic particles given off by the collisions. In a few years this discovery would lead not only to controlled nuclear fission, but it has also led to the use of neutrons in fields from industry to medicine, especially in a type of cancer treatment in which non-radioactive boron 10 is irradiated by neutrons which makes it able to destroy cancer cells.

An example of one of the important uses of neutron bombardment in industry is the work done at the Spallation Neutron Source at the Oak Ridge National Laboratory in Tennessee, a facility where the world’s most intense pulsed neutron beams are produced. Scientists and manufacturers from around the world use this powerful neutron bombardment to test the atomic structure of a variety of manufactured products such as metals, chemicals, and drugs.

In 1930, physicist Wolfgang Pauli discovered that during proton beta decay, protons become neutrons and emit a chargeless and almost massless fundamental particle that for some time was also nameless. Fermi analyzed the particle and named it a neutrino, Italian for little neutral one. The name stuck, and today laboratories around the world are doing in-depth study on neutrinos as possibly being involved in the makeup of dark matter and dark energy that together constitute about 95% of the matter in our universe.

Fermi’s work in neutrons, neutrinos and other subatomic particles was considered so important that at the age of 37 he was awarded the 1938 Nobel Prize in physics “for his demonstrations of the existence of new radioactive elements produced by neutron irradiation, and for his related discovery of nuclear reactions brought about by slow neutrons”. Obviously, neutron research was becoming very important.

By the late 1930s, Fermi and his wife had become disillusioned with Italian fascism, especially after Benito Mussolini, who had been declared Il Duce, had joined forces with Adolf Hitler, Der Fuhrer.  A serious concern stemmed from the fact that Fermi’s wife Laura was of Jewish ancestry and they feared for her safety. In order to escape from danger, when Fermi, his wife, and two young children traveled to Sweden to accept the Nobel Prize, they did not return to Italy after the ceremonies but emigrated to America. Fermi’s reputation as one of the world’s top physicists was such that upon his arrival in New York he was offered positions at 5 American universities. Out of these he chose Columbia University in New York where he was appointed full professor of physics.

After teaching three years at Columbia, in 1942 Fermi took a position at the University of Chicago. This turned out to be a fateful move. In late 1941, fearful that Nazi Germany might be building a nuclear bomb, the United States government had established the Manhattan Project to build a bomb based on nuclear fission. At Chicago, with funding from the Manhattan Project, Fermi set up a large laboratory in a racquet ball court underneath the stands of a football stadium, Stagg Field, where he and his team of 14 scientists — 13 men and 1 woman — began doing research on nuclear fission. In order to not advertise the research going on there, he called his large laboratory the Metallurgical Laboratory. It was here that he and his colleagues built the first atomic reactor, which they called an atomic ‘pile’.

The famous pile was a structure 25 feet across and 20 feet tall. It contained some 30 tons of graphite blocks and 8 tons of uranium. Construction began in September, but the materials were heavy, and the reactor took a while to build. Then on December 2, 1942 the pile ‘went critical’ and achieved the world’s first controlled nuclear chain reaction.

‘Going critical’ occurs when neutrons shot into the atoms of a radioactive material such as uranium 235 – which has 92 protons, 92 electrons, and 143 neutrons — split the atoms in two and these split atoms in turn send out other neutrons that hit other atoms causing them to fission or split and keep the process going. The chain reaction process also produces gamma rays and neutrinos, and generates a large amount of energy as predicted by Albert Einstein’s equation that says that the amount of energy in a material is equal to its mass times the speed of light squared. In other words, a small amount of fissile material will produce a considerable amount of energy and heat. If not controlled, as in a bomb explosion, the reaction produces lots of energy in a very short period of time. A controlled reaction, such as in a nuclear power plant, can last much longer and generate enough heat to run steam turbines. Fermi’s controlled nuclear reaction at Chicago lasted 28 minutes, and the world has not been the same since.

Following his success with the Chicago reactor, Fermi moved to Los Alamos, New Mexico and became involved in the top-secret Manhattan Project which had been assigned the task of developing an atomic bomb before Nazi Germany. Fermi’s job was to set up other reactors which would produce fissionable material that could be used in bombs.  As a result, he did a great deal of traveling out of his base at Los Alamos where Robert Oppenheimer, Edward Teller and others had set up their bomb design operation.

One of Fermi’s projects was at Oak Ridge, Tennessee, a wooded area a few miles west of Knoxville, which had been chosen as the site for a large graphite reactor. Fermi’s job was to supervise the construction of a reactor that would produce weapons grade uranium 235, an isotope of uranium 238 that is enriched and made more radioactive than the naturally occurring U238. It also made small amounts of plutonium 239, a synthetically produced radioactive material that had been discovered in December 1940 by Glenn Seaborg that is less complex to produce than uranium 235. Like uranium 235, bombarding plutonium with neutrons will create a high energy chain reaction. Under Fermi’s supervision the Oak Ridge reactor went critical on the morning of November 5, 1943. In a few months it succeeded in producing several hundred pounds of enriched uranium 235 as well as a few grams of plutonium 239 that were sent to Los Alamos for use in bomb development research.

The next reactor Fermi worked on was built at Hanford, Washington, on the Columbia River. Engineered a bit differently from the Oak Ridge reactor, the Hanford reactor was built primarily to produce plutonium rather than change uranium 238 into uranium 235. The Hanford chain reaction went critical on September 26, 1944. Like the enriched uranium produced at Oak ridge, Hanford’s plutonium was sent to the scientists at Los Alamos where it was put into bombs.

Since there was concern that German scientists were making progress on a fission bomb, at both Hanford and Oak Ridge, there was a strong sense of urgency that the United States needed to build a bomb first. Through the use of war time eminent domain, local residents were hurriedly moved out to make room for laboratories, the huge reactor buildings, and housing for construction workers and scientists. In just a few months these remote sites were converted into busy and crowded cities. In just 18 months, for example, Oak Ridge grew from a small farming community to a city of 75,000 people. The work being done was top secret and most of the residents other than a few top scientists did not know exactly what they were working on.

The big plan worked and the bomb was built. When the first atomic bomb was tested on July 16, 1945 at Alamogordo, New Mexico, Enrico Fermi was one of 425 scientists, engineers, and technicians to witness the blast. Two other bombs were then built. Little Boy, the bomb dropped on Hiroshima, Japan on August 6, 1945 contained uranium that had been enriched at the Oak Ridge reactor. Fat Man, the bomb dropped on Nagasaki, Japan on August 9, 1945 contained plutonium produced at Hanford, Washington. These blasts prompted Japan to surrender, thus ending WWII. Since allied bombing had destroyed many of their research facilities, Nazi Germany never succeeded in building an atomic bomb.

After the war Fermi went back to the physics department at the University of Chicago. While there he also worked with the US Atomic Energy Commission and was instrumental in establishing the Argonne National Laboratory at Lamont, Illinois in February 1946. The name was derived from the Argonne Forest in France, site of several battles during World War I. Today Argonne National Laboratory is a world- renowned center for physics research, materials science, biology, and computer science.

In the late 1940s when the US government was considering the construction of a hydrogen bomb advocated by Fermi’s fellow scientist Edward Teller, Fermi and his colleague Robert Oppenheimer opposed it. Whereas the bombs Fermi and Oppenheimer helped develop were fission bombs, the hydrogen bomb is a fusion bomb, much more difficult to build and much more destructive. Fermi did not feel the world needed a bigger, more destructive bomb.

But is spite of the protests of Fermi, Oppenheimer and other scientists, America went ahead with the hydrogen bomb. The first test in November 1952 was successful, and in August of the next year, the Soviet Union, which at that time had an efficient spy network in America, followed with their hydrogen bomb explosion. With these tests, the cold war between the United States and the Soviet Union had made the world a much more dangerous place. But, after the two tests, Edward Teller was quoted as saying: “Had we not pursued the hydrogen bomb, there is a very real threat that we would now all be speaking Russian. I have no regrets”.

Perhaps like Teller with the hydrogen fusion bomb, Fermi had no regrets about his work on the fission bomb. He felt compelled, however, to say something about how we would use this new atomic technology that could be of great benefit to humanity or lead to humanity’s end if we are not careful. He is quoted as saying: “History of science and technology has consistently taught us that scientific advances in basic understanding have sooner or later led to technical and industrial applications that have revolutionized our way of life. It seems to me improbable that this effort to get at the structure of matter should be an exception to the rule. What is less certain, and what we all fervently hope, is that man will soon grow sufficiently adult to make good use of the powers he acquires over nature”.

We have certainly made good use of the technology Fermi helped develop in such things as medicine, industry, and power generation. But he would no-doubt be saddened that we have not yet become ‘sufficiently adult’ to stop using the technology to create deadly weapons. The number of nuclear weapons in the world today has become a serious and frightening situation.

Fermi spent the next years at the University of Chicago and at the Argonne National Laboratory. In the early 1950s his health declined, and he died at his home in Chicago in 1954 of stomach cancer at the age of 53. Did his years of hands-on exposure to radiation bring on disease as it had done with other scientists who worked with radioactive materials? We know, for example, that Marie Curie died of pernicious anemia brought on by years of exposure to radiation. Theoretical physicist, Edward Teller, on the other hand, lived to be 95.

Perhaps George Washington, Benjamin Franklin, and Abraham Lincoln have had more cities, schools, roads, or institutions named after them, but Enrico Fermi is probably right up there with Albert Einstein as to scientists who have the most things named after them.  And he may actually be ahead of Einstein on both the smallest and the largest structures carrying the Fermi name. Here are a few examples.

The smallest of Fermi’s namesakes are fermions, a group of sub-atomic particles which includes such things as quarks, electrons, and neutrinos. These are considered fundamental particles in that they are not made of smaller particles. Since our bodies and everything around us are made of atoms, it can be said that all physical matter is made of fermions. Quarks, for example, make up the protons and neutrons in the center of atoms. Electrons are the parts of atoms that orbit around the protons and neutrons. And so far, physicists have not found any particle that has mass that is smaller than a neutrino. Neutrinos are everywhere in the universe. Trillions of them go through our bodies every hour without reacting with us at all.

Then there is Fermium, a radioactive synthetic metallic element, number 100 on the periodic table, which contains 100 protons, 100 electrons, and 157 neutrons in its most common isotope. It does not occur naturally and was discovered in the fallout material from the first hydrogen bomb test in 1952 in the Marshall Islands. Fermium can be made in a controlled bombardment of neutrons into plutonium. It is highly radioactive and is used in scientific research.

The electromagnetic frequencies we can see with our eyes, the visible spectrum from red to violet, are only a small section of the entire electromagnetic spectrum that ranges from low frequency radio waves to high frequency gamma rays. In order to ‘see’ things in the universe that cannot be seen with visual telescopes we use radio telescopes on Earth and NASA and other organizations have launched telescopes into Earth orbit which are built to detect frequencies below and above the visible spectrum. One of these is the Fermi Gamma Ray Telescope, launched in June 2008 and currently orbiting 340 miles above Earth. Since gamma rays are absorbed in Earth’s atmosphere, they cannot be detected by ground-based optical or radio telescopes.

Traveling at approximately 17,000 miles per hour, the Fermi telescope orbits Earth every 95 minutes scanning the universe looking for high energy, high frequency gamma rays that are far beyond the frequency range that can be seen through a regular telescope. The telescope’s solar panels produce 1,500 watts of power to keep its instruments running. Its receivers are tuned to pick up gamma rays produced by black holes, stars, solar flares, as well as the powerful gamma ray beams emitted by pulsars or neutron stars which are the remnants of collapsed giant stars.

Gamma rays are the most energetic and dangerous form of electromagnetic radiation in the universe and have a wavelength much too small to be seen with the human eye. Fortunately for us, most gamma rays in space are absorbed by ozone in Earth’s upper atmosphere and do not reach us. They are, however, produced on Earth by radioactive materials and inside nuclear reactors. People who work around substances emitting gamma rays must be shielded carefully.

One of the biggest surprises found by the Fermi telescope so far are Fermi Bubbles. The bubbles originate from above and below – at least as we see it from Earth – the huge black hole at the center of our Milky Way galaxy, a black hole that is some 4 million times the mass of our sun. These enormous bubbles are made of hot plasma that is about 18 million degrees Fahrenheit which has been spewing out below and above the plane of our galaxy for about 3 to 5 million years and moving at a speed of nearly 2 million miles per hour. It is believed that Fermi Bubbles are composed of mostly silicon, carbon, and aluminum, and other elements that are produced inside stars. Inside the bubbles, electrons interact with photons and that is what produces the gamma rays seen by the Fermi telescope.

Fermi bubbles are big: some 25,000 light years long from top to bottom or about 50,000 light years from the top of one to the top of the other, and 1,400 light years wide. In fact, it would take as long to travel from the bottom of a Fermi bubble at the black hole to its top as it would take us Earthlings traveling in a rocket at the speed of light to reach the center of the Milky Way 25,000 light years away.

There are a few theories as to how the bubbles were formed such as the possibility that a giant star exploded near the event horizon of our galaxy’s black hole some 5 million years ago and that its gases are lingering at the black hole’s event horizon. But so far no one knows for sure. So, we could say that not only does Enrico Fermi have one of the largest structures in our galaxy named after him, but one of the most mysterious as well.

It is interesting that even though humans have been studying the sky with telescopes for well over 400 years, we had never detected the gigantic Fermi Bubbles, some 25,000 light years away from us. They are one of the most impressive things in our galaxy, but since the frequencies of light given off by the bubbles are invisible to our eyes, they had not been seen through telescopes on Earth or with the Hubble Telescope which operates in the infrared, visible, and ultraviolet part of the electromagnetic spectrum. It was not until 2010 that the Fermi Gamma Ray Telescope detected the bubbles, emphasizing the fact that the universe is full of surprises and continues to astound us.

One of the world’s premier particle physics and accelerator laboratories is Fermilab located on a 6,800-acre campus in Batavia, Illinois about 40 miles west of Chicago. Started in 1968 as the National Accelerator Laboratory, it was officially dedicated as Fermilab in May 1974. For several years it housed the world’s largest particle accelerator until 2008 when the Large Hadron Collider on the Swiss-French border began operation. Today among the 1,750 people who work at Fermilab are hundreds of scientists and technicians from every part of the world who are doing cutting-edge research on such things as quantum computing and the composition of a number of subatomic particles. A good deal of research, for example, is currently being done on neutrinos, one of the tiniest and hardest to detect sub-atomic particles discovered so far. They are so small and elusive they can only be detected when they interact with another particle.  

To facilitate the neutrino research, there is currently under construction at Fermilab the Deep Underground Neutrino Experiment or DUNE which will use protons to generate a strong beam of neutrinos and send it from Fermilab to a particle detector located 800 miles away at the Sanford Underground Research Facility in South Dakota, the site of a former gold mine. Scientists believe that by helping them understand the nature of neutrinos, this experiment will give them a better idea of the composition of dark matter and dark energy which we know little about beyond the fact that we can see the effects their gravity has on the movement of galaxies. Learning more about dark matter and dark energy might help explain phenomena such as why galaxies rotate and why the universe is expanding and what its future might be.

The phrase Fermi Paradox apparently originated during a conversation that touched on the question of how many planets orbiting the millions of stars in the universe, or even in just the Milky Way galaxy, could be inhabited with intelligent life. Fermi asked that since there are so many possible life forms in the universe, and that surely some of them have developed interstellar travel, then where are they? The phrase is now used in reference to the possibility of intelligent life beyond our solar system. The Search for Extraterrestrial Intelligence (SETI) is an organization of scientists working on detecting life on ‘exoplanets’ and solving the Fermi Paradox.

The Fermi Interaction, developed by Fermi in 1933 not long after James Chadwick’s discovery of the neutron, explains the break-up or beta decay of a neutron in a radioactive atom which emits a proton, electron, and neutrino, particles which were not in the neutron to start with. This work led to the discovery of the ‘weak nuclear interaction’ that today is considered, along with gravity, electromagnetism, and the strong nuclear force to be one of the four fundamental forces of nature.

A phenomenon called the Fermi Energy Surface explains how electrons move to different energy levels inside an atom. When electrons move from a high energy level to a lower energy level, their excess energy is given off in the form of a photon. The study of electron movement on Fermi Surfaces is called Fermiology.

Fermi Energy is a term used in quantum mechanics that concerns the energy level of electrons at a temperature of absolute zero. It is used to define the energy of electrons in semiconductors and even in things as large as white dwarfs which are collapsed stars that have a mass comparable to our sun but are much smaller. In about five billion years our sun will cease fusing hydrogen to helium and become a white dwarf about the size of Earth.

The list goes on. A number of schools, awards, streets, scientific phenomena, and many other things have been named after Enrico Fermi. His work has had an everlasting impact on our way of life. Many of his discoveries have become important in such fields as medicine, particle research into the nature of the matter we are made of, atomic power generation, as well as military weaponry. Enrico Fermi changed the world like few people before or after him. Yet, in spite of his intense dedication to nuclear science, has been described as a friendly fellow with a good sense of humor and a ‘steady’ personality. When a reporter asked him one time how he managed to remember all the names of the numerous atomic particles such as electrons, muons, protons, neutrons, mesons, pi mesons, bosons, baryons, and many others, he responded that “If I could remember the names of all of these particles, I would have been a botanist”. No doubt he would have been as great a botanist as he was a physicist.