“I learned mathematics from Born and physics from Bohr, and from Sommerfeld I learned optimism.”
– Werner Heisenberg
While the Bohr-Sommerfeld atom had proved revolutionary in the mid-1910s, a decade later the model was considered disordered and highly paradoxical. For years, researchers had tried to rebuild mathematics to fit the atomic model of the day.
Instead of struggling along the same path as his contemporaries, Werner Heisenberg, a young German physicist, chose to entirely ignore visual models and focus on the mathematics of spectral data. Over the course of several days, by limiting himself to hard, verifiable data, Heisenberg created the basis for matrix mechanics. In cooperation with Max Born and Pascual Jordan, he was able to refine his work, allowing scientists to approach particles as evolving matrices rather than stale, immobile ball-and-stick models. Through his study of particles using matrix mechanics, he was able to develop a detailed theory suggesting that it was impossible to pinpoint both the momentum and the exact location of any given particle at a specific point in time. Instead, he argued, it was possible to create a probability distribution which could be used to calculate the likelihood of a particle achieving an exact momentum and position at a particular moment.
In late March of 1927, Heisenberg published a manuscript entitled “On the perceptual content of quantum theoretical kinematics and mechanics.” The paper detailed the terms of his probability theory, eventually known as the indeterminacy principle, or more commonly, the Heisenberg Uncertainty Principle. According to David Cassidy, author of Uncertainty: The Life and Science of Werner Heisenberg, Heisenberg’s paper, coupled with Bohr’s complementarity principle and Born’s statistical interpretation of Schrodinger’s wave function, formed an integral part of the Copenhagen interpretation of quantum mechanics. Cassidy calls the Copenhagen interpretation “an explication of mechanics that fundamentally altered our understanding of nature and our relation to it,” and an event that “marked the end of a profound transformation in physics that has not been equaled since.” In this way, Heisenberg was able to reshape scientists’ understanding of the world at the molecular level.
Linus Pauling had the great fortune of touring Europe on a Guggenheim Fellowship during the time of Heisenberg’s discovery. During his stay in Germany, Pauling visited the Göttingen Institute of Physics, the home of Max Born, Arnold Sommerfeld, and of course, Werner Heisenberg. The institute’s renowned scientists, determined to educate their students on the newest developments in their fields, were known for presenting cutting-edge research in their day-to-day lectures. In true Göttingen fashion, Max Born, the famed physicist and mathematician, presented the young visitor with a pre-publication copy of Heisenberg’s paper. We are pleased to note the final pre-publication proof sheets, item corr155.1, is a part of the Ava Helen and Linus Pauling Papers.
Listen: Pauling discusses his contacts with some of Europe’s finest scientists in the mid-1920s
As groundbreaking as the Heisenberg Uncertainty Principle was, Pauling and many of his fellow scientists found the matrix approach to be frustratingly mathematical. Much of Pauling’s work was heavily influenced by Heisenberg’s discoveries and he commonly introduced some of the concepts in his lectures, but ultimately he struggled with the abstract, intangible aspects of the math-based matrix mechanics.
Erwin Schrödinger’s work, which complemented Heisenberg’s complex mathematics, was comparatively simple and conducive to visual representation. As such, it was much more widely adopted by the researchers of the day. Both individuals quickly became known as titans of twentieth-century science.
Learn more at the website “Linus Pauling and the Nature of the Chemical Bond: A Documentary History,” or by clicking on the multimedia link below.