Heisenberg talks about Einstein.

Werner Heisenberg was born in 1901 and died in 1976. He was four years old when Einstein formulated special relativity in 1905. Ten years later, when he was in high school, Heisenberg became interested in Einstein's theory and started his physics career out of his respect for Einstein. However, these two great physicists did not like each other. What went wrong? The basic point is well known. Einstein never accepted Heisenberg's uncertainty principle as a fundamental physical law.

It would be interesting to see what Heisenberg says about Einstein in his book entitled "Encounters with Einstein." This book has a chapter entitled "Encounters and Conversations with Albert Einstein" covering 17 pages. It would be very nice if you could read this chapter from this webpage, but I was not able to get permission to put it on my website from Princeton University Press who published the latest edition of this book. They said their policy is not to allow any of the contents of their books to be placed on internet pages.

This book has an interesting history. It was copyrighted by Werner Heisenberg in 1983, presumably by the Heisenberg estate. It was originally published by Seabury Press (San Francisco) in 1983 as "Tradition in Science," and is reprinted by Princeton University Press in the Princeton Science Library Edition by arrangement with Harper and Row in 1989. This book contains nine articles written in English by Heisenberg. While I am not allowed to place on my webpage his article on Einstein, I do have the liberty of writing a review of the article summarizing the contents of what he says there, with my own opinions.

Heisenberg liked mathematics and became interested in special relativity when he was very young. The mathematics of Lorentz transformations was easy for him to understand, but the physical concept of simultaneity was very difficult for him to grasp. I suspect that this was his communication gap he had with Einstein, as I will explain later in this article. When he was in college in Munich, he learned about Einstein and his theories from Arnold Sommerfeld who was a great teacher to him. Sommerfeld also recognized Heisenberg's potential and encouraged him to meet Einstein personally. The first step toward this process was to attend Einstein's lectures.

In addition, Heisenberg became quite interested in atomic physics which was Sommerfeld's main subject. He was interested in the question of why classical theories fail to explain atomic phenomena, and how the concept of light quanta, formulated by Einstein, could explain those "anomalies." As is well known, Heisenberg's concentrated effort to resolve those puzzles led him to formulate his uncertainty principle in 1927. In the same book (which contains his article about Einstein), he has chapters entitled "Development of Concepts in the History of Quantum Mechanics," and "The Beginnings of Quantum Mechanics in Goettingen." Quite understandably, they constitute the first and second chapters of his book.

In the summer of 1922, the Society of German Scientists and Physicists had a meeting in Leipzig, and Einstein was scheduled to give a lecture. Sommerfeld encouraged Heisenberg to attend Einstein's talk. When he went there, a young man gave him a red leaflet saying that the theory of relativity is a totally unproved Jewish speculation, and that it had been undeservedly amplified by through Jewish newspapers on behalf Einstein, a fellow-member of their race. Heisenberg noted there that those leaflets were being handed out by the students of Germany's most respected experimental physicist at that time. Heisenberg did not mention his name, but it is not difficult who that most respected experimentalist was. Instead of Einstein, von Laue gave his lecture. Heisenberg's first attempt to meet Einstein failed in this way.

In early 1926, Heisenberg was invited to give a colloquium on his quantum mechanics by the physicists in Berlin. At that time, Berlin was the citadel of physics. The audience included Planck, von Laue, Nernst, and Einstein. Einstein was quite interested in Heisenberg's talk, and invited Heisenberg to come to his house. This was his first meeting with Einstein. However, Einstein was not happy with Heisenberg's interpretation of his new mechanics. Einstein's position was that every theory in fact contains unobservable quantities. The principle of employing only observable quantities simply cannot be consistently carried out.

In the spring of 1927, Heisenberg succeeded in formulating his uncertainty relation, emboldened by the wave mechanics formulated by Erwin Schroedinger in 1926 where electrons are regarded as waves. In the autumn of 1927, Heisenberg met Einstein again at the Solvay Congress in Brussels. There Einstein came up with one counter-example to the uncertainty principle each morning, but, by the dinner time, Heisenberg together with Bohr and Pauli were able to prove that Einstein's example was consistent with the uncertainty principle.

Three years later in 1930, Heisenberg met Einstein again at another Solvay Congress in Brussels. There, Bohr did his best to convince Einstein that the uncertainty relations is a fundamental law in physics. Einstein still refused, and they agreed to disagree. It was his last time to see Einstein in Europe. By 1933, the political environment became much worse in Germany, and Einstein moved to the United States. He lived and worked in Princeton where he gave his earlier lecture in 1921.

In 1954, Heisenberg visited Einstein's house in Princeton. Heisenberg was warned by Einstein's assistant not to stay with him more than one hour because of his poor health. Yet, Heisenberg recollects that Einstein was kind enough to spend almost whole afternoon with him. They talked only about physics, but Einstein's position on uncertainty relation remained unchanged. Again, Heisenberg failed to get Einstein's endorsement of his principle as a fundamental physical law. Einstein died in 1955, and Heisenberg died in 1976. According to Johanna Fantova, Einstein was not happy with Heisenberg.

I would like to encourage you to read Heisenberg's article directly from his book, instead of relying on my comments. Yet, I do have the following comments.

1. Einstein, Podolsky, and Rosen published their paper in 1935. Heisenberg did not mention this EPR paper in his article.

2. Heisenberg pointed out that Einstein once declared himself as a pacifist. He then said, in view of his support for the development of nuclear weapons in the United States, Einstein is not an absolute pacifist, but a pacifist with some adjective. Here, Heisenberg forgot to mention whether Hitler's Nazi set-up was an absolute evil or an evil with a different adjective.

3. In his article, Heisenberg says the concept of Einstein's simultaneity was very difficult to digest. That is right, the simultaneity (or simultaneous measurements) plays a pivotal role in interpreting the uncertainty relations. Yet, Heisenberg's interpretation of his uncertainty does not take into account the Lorentz covariance dictated by special relativity. If Heisenberg had studied this cavariance question in interpreting his uncertainty principle, he could have drawn more interest from Einstein.

4. Gift to Einstein. Heisenberg could have brought this gift to Einstein when he went to Einstein's house in 1954.

On the question of simultaneity, it is not right for us to blame Heisenberg. There are many papers these days dealing with uncertainty relations, and many papers having to do with Lorentz boosts from the rest to infinite-momentum frames. There are also many papers where the time variable is regarded as an imaginary number. Do we ever worry about a reconciliation of Einstein's view and Heisenberg's view on simultaneity? Not many people know exactly what I am doing in physics. Most of them assume that I provide public services, such as this Confmenu program, because I cannot do physics. If you are one of those, you are invited to read my papers on the question of relativistic simultaneity in quantum mechanics. Click here for my latest installment on this subject. I have been working with Marilyn Noz since 1973. Here is a my photo with her taken in 1978. Another photo taken in 2003.