Baron Ernst Carl Gerlach Stückelberg was one of the most accomplished theoretical physicists of the middle twentieth century. He ranked alongside such greats as Feynman, Dirac and Fermi, but you could be forgiven for not knowing it. His name appears in physics text books only when attached to some relatively minor phenomena such as the Stückelberg mechanism. Even in popular physics books that recount the glorious history of that golden age of discovery in physics, he is rarely mentioned. Yet Stückelberg made prior breakthroughs in at least three developments that led to Nobel prizes for others, and he contributed to a wide range of other research topics in particle physics and quantum theory.
Here is a short list of some of his greatest achievements (taken from Wikipedia)
- 1934: He devised a fully covariant perturbation theory for quantum fields that was more powerful than other formulations of the time.
- 1935: He gave vector boson (meson) exchange as the theoretical explanation of the strong nuclear force. This is normally credited to Yukawa who discovered it independently at around the same time, and who was awarded the Nobel Prize.
- 1938: He recognized that massive electrodynamics contains a hidden scalar, and formulated an affine version of what would become known as the Abelian Higgs mechanism.
- 1938: He proposed the law of conservation of baryon number.
- 1941: He presented the evolution parameter theory that is the basis for recent work in relativistic dynamics
- 1942: He proposed the interpretation of the positron as a negative energy electron traveling backward in time, an observation often attributed to Feynman.
- 1943: He came up with a renormalization program to attack the problems of infinities in quantum electrodynamics (QED). This was a precursor to the fully renormalized theory of QED completed in the 1940s which netted a Nobel prize for Feynman, Schwinger and Tomonaga.
- 1953: He and Andre Petermann discovered the renormalization group, but it was Kenneth Wilson who took the Nobel Prize for work that demonstrated its full worth in critical phenomena.
So why is Stückelberg not more widely recognised for these achievements? There seems to have been a number of factors at work. Firstly he had some bad luck with publications. He did not publish his work on the meson simply because Pauli said it was ridiculous. His work on the renormalization program was rejected by the Physical Review who said it was more of a program outline than a paper. Sadly no copy of this work was preserved. He is said to have gone on to develop a full theory of QED by 1945 which is recorded in the thesis of one of his students but the credit went to others.
Another element may have been his isolation in Switzerland before and during the war when he did some of his best work. However this seems unconvincing when you consider that he established good friendships with other well-known physicists of the time. He could be considered less isolated than physicists working in Japan such as Tomonaga whose work on QED was recognised later. One other contributing factor that is given part blame for his lack of credit is that he invented unusual notation for his work that made it difficult to read.
Whatever the cause, he ended his life feeling lonely and rejected. When Feynman gave a lecture in Switzerland in 1965 he spotted Stückelberg after the lecture leaving quietly from the back. Pointing to Stückelberg, Feynman remarked ”He did the work and walks alone toward the sunset; and, here I am, covered in all the glory, which rightfully should be his!”
The story of Stückelberg shows just how easy it is to be overlooked in science. There is no convincing reason why he was not given the full credit he deserved for his work, but it would have helped if he had presented his work more clearly and fully. While people like Feynman gave seminars and wrote books, Stückelberg seems to have quietly accepted his rejections and left it to others to speak up for him. But that was something they did not do enough. There is a lesson to be learnt here. Most of us cannot claim achievements comparable to those of Stückelberg so if he can be overlooked the rest of us should take nothing for granted. It does no good to make a discovery and bury it so deep that nobody pays any attention until it is rediscovered by someone else who is better at presenting it. Research needs to be explained clearly and publicly or it sinks into obscurity.