A complementary perspective on quantum history

Complementarity applies not only to quantum physics but to its history. Ryan Dahn’s article “Demythologizing quantum history ” (Physics Today, April 2025, page 38) provides the side of the story that comes naturally to historians, who weave webs of interconnections among all participants, figuring out who contributed what and who influenced whom. With that perspective, it is hard to give too much credit to a singular act of discovery, because the “aha” moment has been preceded not only by the preparatory work of the individual but by the work of many others as well.

The complementary perspective is that of the research physicist. Research can be frustrating. One can spend large amounts of time getting precisely nowhere. Then, suddenly, there might be a moment of clarity, a new way forward. Few have experienced a breakthrough as significant as Werner Heisenberg’s in the summer of 1925, but similar, if usually lesser, rewards are what researchers crave.

The details of an actual breakthrough may not appear very impressive. The Wright brothers’ famous “first flight” in 1903 traveled only 37 meters and lasted only 12 seconds, but it opened up a whole new universe of aviation. It is likewise not surprising that Heisenberg’s Umdeutung (“reinterpretation”) paper was sketchy and hard to understand. It is also not surprising that he was uncertain (no pun intended) about the worth of his achievement; new ideas often do not pan out. It is greatly to the credit of Max Born and Pascual Jordan that they were able to turn Heisenberg’s insight into a cogent theory of the atomic world.

Looking back in 1963 on his trip to Helgoland, Heisenberg said he remembered feeling, “Well, now something has happened.” ¹ In later years, he may have been vague on the details, but the reality of the breakthrough seems to have been seared in his memory.