Enrico Fermi’s Body of Work
Iconic image of Enrico, demonstrating at the blackboard. It was a staged publicity photo, including in the uncropped version a mis-written formula. This image was also the basis for a US postage stamp and an Italian postage stamp. Both were issued in 2001 to commemorate the centennial of Enrico’s birth.
I am not a physicist. I’ve patiently listened to and read lay explanations of Enrico Fermi’s most important theories and experiments — all in the hopes of understanding his place in the quantum revolution and the emergence of atomic energy and the nuclear bomb.
Physicists and engineers routinely tell me, “Your grandfather is up there with Einstein – you can’t say who is more important.”
Why if my grandfather’s contributions were so significant was he not a household name? What is Enrico’s impact in our world today? I launched the FermiEffect website in 1999 to see if I could find answers and share them.
(Ultimately the existence and use of nuclear bombs; and the environmental and human health hazards of nuclear production (whether for war or for peace) led me to a deeper quest initially inspired by my grandmother Laura Fermi. The Neutron Trail is an ongoing inquiry into our shared nuclear legacy and choices about where to go next.)
I knew, weak force, beta-decay, Fermi-Dirac statistics, his Nobel Prize winning work in Rome and the Chicago Pile were Enrico’s most famous and perhaps most important works. But what did it all really mean?
In early 2011, as I researched for a potential feature-length documentary on the Neutron Trial, these questions I’d wondered about for over a decade, finally, began to yield answers. It dawned on me beta decay is a technical term for radioactive decay. This says Enrico described how naturally occurring and manmade radioactive elements (isotopes) fall apart. Okay. That’s obviously important.
The night before we shot the first footage for the Neutron Trail documentary, Enrico’s work on radioactive (beta) decay must have been on my mind. I awoke in the night, excited about the shoot. As I lay in bed, the fragments of understanding I’d collected coalesced.
I could see why Enrico’s work was such a big deal to quantum physics. Really, I think it is the strange titles of his theorems and experiments, which leave most of us in the dark. Plus his work is integral to the atomic bomb and naturally nuclear annihilation is not a popular topic!
Something else happened overnight, while I was musing about my grandfather’s role in atomic energy and the bomb. I learned of it moments before I left for the documentary film shoot. At 8:10 am on Friday, March 11, I read our executive producer’s emails: “Anything we can do re shooting today to cover reactor cooling loss in Japan?” and then, “Reactor under control.” [Later events proved Japanese reactors weren’t under control.]
Stunned I browsed and learned: less than twelve hours ago a massive earthquake, 8.9 on the Richter scale had hit Northern Japan along with a tsunami. In the car, the producers and I talked about the earthquake, the tsunami and a potential manmade disaster should one or more of the nuclear reactors in the earthquake zone release massive amounts of radiation. [As of this writing, Monday, March 14, 2011 the situation continues to change with concerns of a meltdown at Fukushima.]
During the night, I realized Enrico’s two most important experiments sprung directly from his profound understanding of the energetic workings of the atom, signified by his theories of beta decay, weak force and Fermi-Dirac statistics.
He proposed the first credible theory of the weak force, one of the four basic forces in nature. The weak force is so weak it’s only relevant on a sub-atomic level. Examples of the weak force relate to radioactive (beta) decay!
Besides understanding how atoms fall apart and release energy, Enrico and his fellow quantum physicists need(ed) to know how atomic particles behave energetically. Fermi-Dirac statistics is about just that — describing how fermions (which include some basic building blocks of atoms: neutrons, protons, electrons) can each only occupy one energy state at a time.
Upon this theoretical base, Fermi and his team, dubbed the Via Panisperna boys, bombarded elements to understand their properties. Enrico made an intuitive leap when he realized slow neutrons would yield more action than fast neutrons. In 1938, Fermi won the Nobel Prize for this work. Subsequent further analysis of his results showed he had split the atom.
In the Chicago Pile experiment, successfully completed December 2, 1942, Fermi and his team again took advantage of slow neutrons to split uranium atoms. They achieved the first-ever controlled, sustained release of energy directly from atoms. The Pile was the first nuclear reactor and the experiment proved an atomic bomb was feasible.
To summarize: with these five pieces of work, Enrico played a pivotal role in unraveling the energetic workings of atoms — how they are put together (Fermi-Dirac statistics and weak force), fall apart (beta decay) and release energy (experiments in Rome with slow neutrons and the Chicago Pile).
During World War II, the early quantum physicists working on the bomb and the development of atomic energy were riffing off of Einstein’s famous equation E=mc2. Literally, the Manhattan Project scientists were taking the “mc2” (mass x speed of light2) — representing huge potential energy locked up inside matter (a.k.a. atoms) — and turning it into vast amounts of E (energy).
Though physicists tell me of Enrico’s all around brilliance in physics, I like to think of him as a neutron genius. He knew the sub-atomic forces so well, he could play them like a billiards champion.
Any of these five major works could have won him a Nobel Prize. At the end of his life, Enrico also discovered the first pion-proton resonance (sorry I haven’t even begun to understand this one quite yet) and contributed many other significant theoretical and experimental works to physics.
As much as my grandfather enjoyed his work, my own feeling is toward the end of his life, Enrico saw the ramifications of it were beyond society’s current ability to handle responsibly. He believed in open science and democracy. Fermi fled Fascist Italy to save his Jewish wife (my grandmother), my mom-to-be and her brother from almost certain extinction by the Nazis.
In 1939, he brought our family to the United States to work and live in a free society. Because, at the time, Italy was aligned with Germany and the Nazi’s, Enrico was classified in the United States as an enemy alien. Yet my grandfather had the highest security clearance allowed to a scientist and a private bodyguard all from the same government.
The threats and pressures of World War II, which involved ideological and territorial battles in Europe and the Pacific, and which ultimately saw 50-70 million people die worldwide, led him to work on the atomic bomb. After the War was over he spoke against the development of the hydrogen bomb, yet when the US government decided to go ahead, he worked on it.
In The Making of the Atomic Bomb, author Richard Rhodes states:
For [Enrico Fermi] the war work was duty, however, and the eager conviction he found [among his fellow scientists] on the Hill [Los Alamos, NM where they developed the first atomic bomb] puzzled him. “After he had sat in on one of his first conferences here,” Oppenheimer [project leader] recalls, “he turned to me and said, ‘I believe your people actually want to make a bomb.’ I remember his voice sounded surprised.”
I have often wondered why my grandfather wasn’t as politically outspoken as some of the other scientists. My hunch, and it’s really only a hunch, is it was a combination of factors. Enrico’s natural reticence to voice an opinion on anything he didn’t thoroughly understand, combined with the pressures of being classified an enemy alien during World War II, helped keep him active in physics and quiet in politics.
He worked with absolute dedication and integrity to his work and with his students. It seems he assumed everyone else (public policy makers, politicians, etc.) was doing the same. I judge this as naiveté or a kind of professional blindness, but not evil, on his part. In his own way, Enrico Fermi was a courageous pioneer, the inspiration for many, who study his work and transcend it — as he would have wished.
Niels Bohr, Robert Oppenheimer, Leo Szilard and many other scientists after World War II were far more outspoken about the need for international cooperation and controls on atomic energy, than was my grandfather. Yet I imagine, again simply based on what I have read and my own intuition, if he were here now, he would whole-heartedly support such work.